Valve timing

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Model T Ford Forum: Forum 2005: Valve timing
Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Tuesday, January 10, 2006 - 10:24 pm:

hi all, i am still attempting to set up my new valves and was wondering if anyone can tell me, at what point (or position) is the piston in, when you "check the gap" between the pushrod end and the valve stem?, by that i mean "when", are you supposed to have a .010 (intake) or .012 (exhaust) reading and how do you get it? i want to set them according to Bruce's method in the engine book, but don't know how to get them to the "initial" settings, the book just says to "set all intake valves to .010 and set all exhaust valves to .012" and procede from there, but it doesn't say "how" to set them!! can someone please explain it to me, i am ready to get the "saws all" out!!!!
thank's ,
den


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie Tosch on Tuesday, January 10, 2006 - 11:12 pm:

Hi Den,

To set the valves, the piston in the cylinder that you are adjusting the valves on must be at top dead center (TDC) on the compression stroke. When this is the case, both valves will be closed and the clearance can be adjusted. As far as I know, this procedure is correct for all engines, not just Model T's.

Charlie


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Wednesday, January 11, 2006 - 01:53 am:

thank's charlie, that's the exact info that i couldn't seem to find. i'll give it a shot.
den


Top of pagePrevious messageNext messageBottom of page Link to this message  By hurc T Yuppin on Wednesday, January 11, 2006 - 02:56 am:

Put a 360 degree wheel on the end of the crank shaft. Turn the crank Lets say 350 degrees is at pointer.Install a stop at this point bole a tab of metal to the block and set a socket under the metal. This makes a good positive stop Turn the crank the other direction until the piston hits the stop and will not travel any further. Take note of the number on the wheel. Lest say the pointer is pointing to 10 degrees. Now add the total degrees not read on the wheel. It should have been 10 degrees +10 degrees which equals 20 degrees. Divide the total by 2 which will be 20/2 =10. Now remove the stop from the piston measuring device. And rotate the engine to one of the numbers where the piston was stopped at on the 360 degree wheel. Add another 10 degrees in those directions. In this case the extra 10 degrees will stop on the 360 or the 0 degree mark on the wheel. (360 and 0 are the same number on the wheel)This is a confusing but worthy way of finding the actual top dead center, There is normally a state of equalibrium or several degrees inwhich the crank will travel. You want to find the actual tdc
with out any equalibrium or play where the crank will move and the piston will not move.

Intake settings
Measure the piston at that point which will be top dead center (TDC) now rotate the engine clockwise until the piston is 1/16” past TDC adjust the tappet so the valve just begins to open, you can see this by looking at the dial indicator the desired position is reached for the intake. When the piston is 1/16” past TDC adjust the intake valve tappet so it just begins to open.
dial indicator on cylinder


Exhaust setting

Measure the piston at that point which will be top dead center (TDC) now rotate the engine clockwise until the piston is 5/16” before bottom dead center adjust the tappet so the valve just begins to open, you can see this by looking at the dial indicator the desired position is reached for the intake. When the piston is 1/16” past TDC adjust the intake valve tappet so it just begins to open.

All settings are done when the valves just open!


position as follows:

Exhaust valve
opens when the piston is 5/16 before bottom center
Exhaust valve
closes at top dead center.

The intake valve
open 1/16 past top dead center or when piston is .250 above the cylinder block.
The intake valve
closes 9/16 past bottom center


This method of timing is one of many ways. Notice the two wrenches in the valve tappet area. One holds the tappet the other adjusts the tappet. In this case the dial indicator is being watched and the valve is being adjusted until the needle on the indicator just begins to move. This method is done on both the exhaust and the intake valve.
Do not use the original valves on your T engine. They were a two-part valve and are prone to break with age. New stainless steel valves are readily available. Do not try to grind the valves to fit the tappet. Replace the old tappet with the adjustable tappet. It will save you hours of work





your valve settings will not all be the same. they may be a tad loose, but this method will wake up a stock T motor that has not been decked


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Wednesday, January 11, 2006 - 05:47 pm:

i have all the intake valves set at .010, and all the exhaust valves at .012, i removeed the front gear cover to try and make sure i was at TDC, the "bible" says to "line up the "0" on the large gear, to the "ford" stamp on the smaller gear. i cannot find a "ford" stamp on the smaller gear, what do i look for now?
den


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie Tosch on Wednesday, January 11, 2006 - 06:30 pm:

Den,

The 'Ford' mark on the smaller gear is really the timing mark on this gear. It may be something else than 'Ford'. In the first picture it's not really sharp, but it looks as though the timing marks on the 2 gears are aligned. Also, the piston looks to be at top dead center. If you can rock the the crankshaft back and forth you should be able to see when the piston comes to a stop before changing direction. This is TDC. If you can't get something like a large adjustable wrench to fit over the starting crank pin in the crank to rock the crankshaft, put the transmission in high gear and give the car a slight push backwards and forwards while watching the piston movement.

Charlie


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie Tosch on Wednesday, January 11, 2006 - 06:34 pm:

Den,

I forgot to mention, there are two top dead centers for each cylinder. The one you need for valve adjustment is the one when both valves are closed. This is the top of the compression stroke when the cylinder is just ready for ignition, not the top dead center when the exhaust valve is open.

Charlie


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Frink on Wednesday, January 11, 2006 - 06:35 pm:

Den, if there isn't a "Ford", there should be a 0, or a punch mark, or a hash mark. The mark will line up with the mark on the large gear at TDC, and line up at 180 degrees from the mark on the large gear at the top of the exhaust stroke. The cranking pin will be horizontal at that point.
When the #1 piston is at the top of its stroke and both valves are completely seated, you are at top dead center.
Bob


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Wednesday, January 11, 2006 - 07:02 pm:

oops, the ol' eyes are getting worse!!!! i found the "ford" stamp on the small gear, didn't know that they could "micro" stamp stuff back then!!!! the "0" and the "ford" do not seem to line up at TDC though.


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Wednesday, January 11, 2006 - 07:22 pm:


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Wednesday, January 11, 2006 - 07:23 pm:

the last picture shows the marks when the #1 piston is at TDC (both valves closed) do i have a problem, or does everything look ok?
den


Top of pagePrevious messageNext messageBottom of page Link to this message  By Michael Nowlin on Wednesday, January 11, 2006 - 07:25 pm:

Den, the Model T is different than many cars in that the number one piston is not at TDC with the timing marks aligned it is slightly down in its bore. Align the Ford with the 0 and you will be ok.


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Wednesday, January 11, 2006 - 08:45 pm:

ok, thank's, i think i've got it and am going to start re-assembling it. one question, the fan pulley slides back on the shaft, and then the "pin" goes through holes in the pulley and the shaft, there is also what looks like a "cotter pin hole on one end of the pin, it was empty when i took the pin out, is there supposed to be a cotter pin in this hole?, what holds the pin in the crank shaft?
thank's again
den


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ross HARRIS on Wednesday, January 11, 2006 - 09:15 pm:

hi all I`m in the process of putting my engine back together with high compression pistons and high lift cam can I set valves in the same manner described above.Any help would be appreciated. Thanks again Ross from Canada.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark on Wednesday, January 11, 2006 - 09:45 pm:

Den

Yes there should be a cotter pin in to hold the crank pin into the crank shaft.

I'm going to assume you have the bottom access pan off of the pan. While you have it apart, I would look up inside the block and make sure that the timing mark on the cam is pointing the same direction as the first lobe on the cam shaft. There's only 2 ways to put the cam gear on because of the alignment pins, but I would check it while you have access to it. I figure you probably didn't have it off and it would be correct, but one never knows if it wasn't running before taking it apart.


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Wednesday, January 11, 2006 - 10:22 pm:

mark, thank's, no i don't have the pan off, the car was running before i replacing the valves, it was just sluggish and lacked power.
den


Top of pagePrevious messageNext messageBottom of page Link to this message  By David_Cockey on Wednesday, January 11, 2006 - 10:36 pm:

Be careful setting valve clearances by the "timing" method if you don't know what the cam grind is. The principle of valve timing is that the clearance is set so that the valves are just beginning to open at with the crankshaft and camshaft at the appropriate position. The potential difficulty is that the appropriate position depends on the cam grind. The usual quoted dimensions apply to an original stock grind. As a camshaft is reground the valve timing frequently changes. If you use the timing method to set valve timing you might want to consider checking the valve clearance afterwards to see that it makes sense.

Hurc's method of measuring piston position relative to TDC is a good one because it eliminates variation due to block decking, piston differences, etc.


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Friday, January 13, 2006 - 01:17 am:

update on the "valve job", i just got done putting everything back together after setting the valves,put the new exhaust system on, put fresh gas in, she just keeps cranking, no pitter, no patter, i succeded in taking a running "T" and "killed it", any suggestions on what i could have messed up guys?, panic is slowly creeping in!!!!!!
den


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money on Friday, January 13, 2006 - 01:38 am:

den, 3 things you need for it to run, Gas, compression, and spark. Verify compression, then spark then gas.


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Friday, January 13, 2006 - 01:48 am:

doug, i tried to get a compression check, but the needle goes up to 30 then comes back down right away it's the same thing that it was doing before i took her apart (she was running ok then) i am wondering if i could have screwed up the timing somehow. the coils are buzzing but i haven't checked for spark yet.
den


Top of pagePrevious messageNext messageBottom of page Link to this message  By hurc T Yuppin on Friday, January 13, 2006 - 02:47 am:

You have to make sure the compression stroke is in the proper position for the timing to be proper and to get the max compression. The method I descriped would have indicated that right away, and given you much more power. You cannot properly time the engine on the wrong stroke. Atleast go back and make a few measurements and see if the valves are opening in the vicinity of the numbers that were given seval threads ago.

Timing on the wrong stroke is like pushing a kid on a swing. You push when the kid is in your hand vicinity (power stroke0. If you tried to push when the kid is at his furthest distance from your ability to push is the equivelant to a engine being 180 degrees out of time.


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Friday, January 13, 2006 - 03:30 am:

sorry hurc, i tried to follow your directions but found out about halfway through,that i didn't understand the language that they were written in, so i pulled the "bible" out and measured them and rechecked them about 5 times until i thought that they were doing what they were supposed to be doing on the right stroke, but it looks like i will be taking it back apart tomorrow and see what exactly is going on. but the compression guage is doing the exact same thing that it was doing before i took it apart and it was running then, maybe my guage is screwed up or something, when i crank the engine the needle goes up to 30 then falls back down again. i checked the shraeder valve on it but everything looks ok, i'll have more time tomorrow to try and salvage this operation.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les on Friday, January 13, 2006 - 09:06 am:

Sometimes the camshaft has the hole for the timer roller pin drilled all the way thru. This would allow the timeing to be off 180 degrees if the pin was installed on the wrong side. This would keep the engine from running.With the spark plugs OUT, pull up the # 1 piston on compression stroke(you will feel air coming out of the spark plug hole)and see if the #1 coil is sending spark to the #1 plug at the top of the stroke. If its not ,the roller may be installed wrong.


Top of pagePrevious messageNext messageBottom of page Link to this message  By hurc T Yuppin on Friday, January 13, 2006 - 10:03 am:

Den, send me your phone number at my e-mail and I will talk you through it. It is worth the little extra effort

hurc
let me know on the forum if you send the number I will respond asap


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Friday, January 13, 2006 - 06:13 pm:

thank's les, i checked it today and the hole doesn't go all the way through, there is only one way to put it back together. i did get her started today though, it turned out to be a "no gas" situation, it starts right up but runs poorly at this point. i'm still messing with it though!
den


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Saturday, January 14, 2006 - 12:52 am:

update on the valve job, i did a compression test and got exactly 30 psi on all 4 cylinders, doesn't that sound a little low?, what can i do now besides tear it back down to see what's going on? thank's
den


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money on Saturday, January 14, 2006 - 01:36 am:

cam timing or ignition timing retarded? recheck those 2 items.


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Saturday, January 14, 2006 - 01:46 am:

thank's doug, how do i check cam timing?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Frink on Saturday, January 14, 2006 - 02:35 am:

According to the pictures, the cam timing should be OK. Try putting some oil in the cylinders, and see if the compression comes up.


Top of pagePrevious messageNext messageBottom of page Link to this message  By andy samuelson on Saturday, January 14, 2006 - 11:35 am:

maybe it is the tester.
i would try a different tester before taking it apart. if all you got was 30 before and all your getting now is 30, i would look at the tester first.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kenneth H. Todd on Saturday, January 14, 2006 - 12:31 pm:

If your comp. tester is an adaptation of a modern one that goes to 200 or 300 lbs I wouldn't trust it at the low end. You need one that max's at 60 or at the most 100 for doing stock T compression.
Did you get the check valve in the tester problem fixed?


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Saturday, January 14, 2006 - 02:50 pm:

thank's guys, originally i was using the tester without the hose, i used a pipe adapter and screwed itt straight in to the plug hole, it turns out that the check valve that holds the pressure while testing, is in the hose itself, so now i am using the hose with the tester, and it is holding air.the guage is still hitting 30 psi max in each cylinder but now it will hold the pressure until i release it. it is a 300 psi modern type guage, i couldn't find a lower numbered compression guage locally, maybe i'll see if i can find one online.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie Tosch on Saturday, January 14, 2006 - 04:42 pm:

Den,

Any way you can remove just your gauge from the tester and replace it with say a lower pressure gauge from a small air compressor, a household water pressure system, or maybe a swimming pool filter pump? You should be able to locate a gauge in a hardware store or at Home Depot. A pressure gauge just reads pressure and it doesn't know where the pressure is coming from.

Charlie


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Saturday, January 14, 2006 - 06:00 pm:

thank's charlie, i wasn't sure if i could use just any gauge or not i'll have one by tonight.


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Saturday, January 14, 2006 - 10:52 pm:

update, i picked up a 100psi gauge, redid the compression test and still came up with 30 on all cylinders. how can it be that low and still run?
i am going to pull the head again and see if i can spot anything out of place.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money on Saturday, January 14, 2006 - 11:28 pm:

Can you do a leakdown test? Use the adapter in the spark plug hole and hook it to your air compressor. Make sure the crank is at top dead center and turn on the air. You will hear it leaking if there is a leak in the motor.


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Sunday, January 15, 2006 - 01:57 am:

doug, i already pulled the head back off, tomorrow, i will check the valve timing again, i don't know what else it could be that is making it run rough or why the compression would only be 30. before i got the gauge, i tried plugging each hole with my thumb, the compression was good enough that i couldn't keep my thumb form being pushed off.


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Sunday, January 15, 2006 - 02:09 am:

here is what it looks like now.
,


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money on Sunday, January 15, 2006 - 03:13 am:

Maybe I am wrong, but that looks like a lot of soot from just assembling the motor. I remember you had the top of the motor very clean. Could it be a rich mixture? These guys will know.


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Sunday, January 15, 2006 - 04:18 am:

it could be from me messing with the mixture screw trying to get it to run smoother, i tried everything that i could think of while it was running. the only thing that i noticed was that the #1 cylinder had a small amount of oil on top of it, it had the same thing when i took the head of the first time.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money on Sunday, January 15, 2006 - 10:41 am:

It sounds stupid I know, but you didn't get any timer wires crossed?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie Tosch on Sunday, January 15, 2006 - 01:13 pm:

Den,

I've been looking at your latest pictures. The picture of the cylinder head shows a really excessive amount of oil in #1 and #3 combustion chambers and there even seem to be small oily deposits in the other 2 combustion chambers. Also, #1 piston looks really oily and there is a lot of oil on the head gasket around #1 cylinder. I don't think this should show on an engine that has been run for such a short period after the good clean up you did. Do you think that your low compression problem could be due to ring wear or lack of ring tension? Did you remove the pistons and check the rings when you did your valve job? If not, I'd remove at least piston #1 and check the rings as this is the cylinder that seems to show the most oil. If your valves are seated well and adjusted properly, then I'd bet you have a ring problem, especially on the #1 cyl. On this cylinder you may have both bad compression rings and a bad oil control ring.

I have a book entitled "MY FORD It's Care and Repair" written in 1925 and here's what it says about low compression. "Every 3000 miles or so the compression of the engine should be tested and if any cylinder is notably weak and yet the valves are properly adjusted, see paragraph 233 below. If weak compression is caused by leaky piston rings and the spark plug will probably be fouled with oil, the engine missing on this cylinder, whereas a dry spark plug probably with regular firing of this cylinder except at low speed, indicates a leaky exhaust valve if the compression is weak. A leaky intake valve will be accompanied by backfiring. If the engine misses with throttle closed and missing ceases with throttle open it is fairly certain that the valves need grinding." From that, and the excesss oil in your combustion chambers, you may be able to conclude that the rings may be a good part of your problem.

Paragraph 233 referred to just goes on to tell how to test the compression which you have already done.

Charlie


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Harris on Sunday, January 15, 2006 - 02:10 pm:

Just looking after the fact and long after the discussion has been started, but it appears that there has been an issue with cam indexing.

With your crank at TDC it appears that all of the valves are doing the right thing with the pistons in the positions that they are in, in the pictures.

Someone mentioned, up above in this string, that you should do a leak down test.

With the engine at TDC on number one (1) blow air in that spark plug hole at about 30 psi. It should hold at 30. If air escapes through the carburetor, you have a bad intake valve. If air escapes through the exhaust pipe, you have a bad exhaust valve. If air escapes through the oil filler hole, you have bad rings. If it escapes through all three places you have a bad engine. If you can't tell what is going on, you can up the pressure but you will have to lock the engine in some manner such as putting it in high gear with the brakes on and wheels chocked.

When crank testing for compression, it is good to have the throttle open all of the way the the choke open all of the way, and all spark plugs removed. Crank it over three times and test the pressure where it is holding. If you test with the throttle closed you will get a low reading.

30 pounds is only two to one. If your cam is actually timed properly and things are reasonably tight with respect to valve seats and rings, you should have about 45 yo 60 pounds. We get 85 pounds and more in our Speedsters.

After checking, put a table spoon of oil in a cylinder and check it again, if it gets better, you have bad rings.

If everything is tight and the readings improve, you need to check spark timing.

If compression does not improve you need rings and valves.


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Sunday, January 15, 2006 - 11:49 pm:

guy's i think i screwed this whole job up!!!! i took everything back apart, and checked the valve clearance again and i am getting all kinds of weird readings, i think i may have "adjusted" some of them while on the exhaust stroke instead of the compression stroke!!!! while i was checking it, i noticed that both valves were closed on the compression stroke AND the exhaust stroke, i was probably getting them "mixed up", i am going to have to order more valves i think and start over again. wish i had "adjustable" tappets now, don't i!!!!!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Flivverboy on Monday, January 16, 2006 - 01:44 am:

Don't sweat it, Den.

One thing I'd do is jack the car up at least a foot to save your back while working on the valves. Those '26s are AWFULLY low.

You don't have adjustable tappets? No better time to put them in. The timing is right to slip in a Stipe cam, too... And you're not going to put that old iron head back on, are you? Gee, those new aluminum ones are swell.


Top of pagePrevious messageNext messageBottom of page Link to this message  By den delano on Monday, January 16, 2006 - 02:23 am:

i just take a lot of "nuprins" for my back, i can usually move again sometime the next afternoon!!! but i did notice that my shirtsleeve is getting a lot tighter in the upper right arm area from all the cranking!!!!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Anthony Bennett on Monday, May 07, 2007 - 11:10 am:

G'day blokes. Reading all this stuff got me to thinking, firstly has anyone ever done the numbers on a standard model T cam to work out what it'd look like in degrees of duration, as conventional advertised timing or .050" lift figres? I've been doing some study on a "modern" Cleveland Ford V8 and wondered if the information existed?
Second thought came about after examining a pile of old T camshaft gears. Seems some of them vary as to the position of the dowels in relation to the teeth. Almost as if they were paired to a particular crank gear or cam. Maybe even changed to give different advance or retard on the whole cam. I realise that timing each valve to each piston is a fine way to tune the old girl up but there must be a few degrees timing variation amongst the assorted gears I have examined, which would give you some advance or retard in the timing if the gears were swapped without re doing the clearances?? Is it just a case of poor manufacturing tolerance perhaps? Any ideas?
I'm spending too much effort and so far no money putting together a clunker engine with some used genuine ford(?) .025"over cast iron pistons, standard old cam etc. Machining such as boring/honing/manifold face/deck/valves/seats/guideshas been free so far. Everything standing still is being balanced. Have to fork out some dollars on trans bushes/bands and a gasket set next:-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem on Tuesday, May 08, 2007 - 10:52 am:

Maybe it's been stated in the many posts above already but I'll just add two hints.

1. The timing mark on the small gear always is on the tooth just above the keyslot. So, even if you can't find a timing mark, just locate the gear tooth immediately above the keyway.

2. The crank pin will be horizontal when the engine is at TDC. The crank pin hole is always drilled perpendicular to the timing gear keyway.


Top of pagePrevious messageNext messageBottom of page Link to this message  By GLEN CHAFFIN on Tuesday, May 08, 2007 - 01:18 pm:

SETTING VALVE CLEARANCE

A SIMPLE PROCEDURE

BY GLEN CHAFFIN

AN ORIGINAL, USED MODEL T FORD CAMSHAFT WILL HAVE REDUCED LIFT AND A CHANGE IN VALVE TIMING CHARACTERISTICS DUE TO NORMAL WEAR ON THE LOBES. EVERY LOBE OF THE CAM WILL HAVE A DIFFERENT WEAR CHARACTERISTIC.
THE ENGINE WILL STILL RUN WELL BUT MAY HAVE A REDUCTION IN OVERALL CAM PERFORMANCE.

BACK IN THE EARLY 1920’S, K.R. WILSON SUGGESTED THAT MODEL T VALVES BE SET USING THE PISTON TRAVEL METHOD. HE EVEN OFFERED A SPECIAL TOOL TO DO THE JOB. THE IDEA WAS TO ADJUST THE OPENING AND CLOSING OF THE VALVES TO CORRESPOND WITH A CERTAIN POSITION OF THE PISTON. IN THEORY THIS WAS A GOOD IDEA AS IT COMPENSATED FOR THE WEAR ON THE CAM LOBES AND RESTORED VALVE TIMING TO THE ORIGINAL FORD SPECIFICATIONS. IN PRACTICE IT CAUSED OTHER PROBLEMS.

MANY ARTICLES HAVE BEEN PUBLISHED IN THE VINTAGE FORD ON HOW TO ADJUST VALVES BY PISTON TRAVEL. HOWEVER, YOU SHOULD KNOW THAT THIS METHOD IS OBSOLETE AND ONLY USEFUL FOR SOMEONE USEING THE ORIGINAL CAST IRON HEAD VALVES AND TRYING TO RESTORE OPTIMUM PERFORMANCE BY ADJUSTING VALVE TIMING TO COMPENSATE FOR A WORN CAMSHAFT. EVERY CAM LOBE HAS A DIFFERENT WEAR PATTERN AND WILL REQUIRE A DIFFERENT ADJUSTMENT TO RESTORE THE ORIGINAL VALVE TIMING. USING THIS METHOD WILL RESULT IN THE VALVE LASH OF EACH VALVE BEING DIFFERENT FROM THE NEXT ONE. WHEN THE PROCEDURE IS COMPLETED TYPICAL VALVE LASH WILL VARY BETWEEN 0.010 IN. AND 0.030 IN. THE NET RESULT WILL BE A MODERATE IMPROVEMENT IN ENGINE PERFORMANCE AT THE EXPENSE OF A VERY NOISY ENGINE.

FORD SET MODEL T VALVE CLEARANCE TO A “THIN DIME”. TYPICALLY, 0.022 TO 0.028 IN. THIS WAS NECESSARY DUE TO THE USE OF CAST IRON HEAD VALVES WHICH HAD A LARGE THERMAL EXPANSION COEFFICIENT. IN TODAYS WORLD ANYONE REBUILDING A MODEL T ENGINE WOULD NOT EVEN THINK OF USING THESE CLEARANCES AND THE POROCEDURE OF SETTING VALVE CLEARANCE BY PISTON TRAVEL IS OBSOLETE. WITH MODERN STAINLESS STEEL VALVES, THE CLEARANCE IS TYPICALLY SET BETWEEN 0.010 IN. AND 0.015 IN. THIS WILL INCREASE VALVE LIFT ABOUT 0.010 IN. AND SLIGHTLY INCREASE VALVE DURATION.

DURATION IS THE TIME DURING WHICH A VALVE IS OPEN MEASURED IN DEGREES OF CAMSHAFT ROTATION. DECREASING VALVE CLEARANCE INCREASES VALVE DURATION. WITH A TYPICAL CAM GRIND, THE VALVE DURATION WILL INCREASE APPROXIMATELY 1 DEGREE FOR EACH 0.001 IN. IN REDUCED CLEARANCE. USING THE NEW RECOMMENDED VALVE CLEARANCE WITH A “STOCK” CAM THE DURATION SHOULD BE INCREASED ABOUT 10 DEGREES TO 228 DEGREES. THE INCREASED LIFT AND DURATION WILL IMPROVE THE ENGINE PERFORMANCE OVER THE ENTIRE OPERATING RANGE OF THE CAM.

MY ORIGINAL 1913 ROADSTER WAS REBUILT USING THE ORIGINAL CAM. THE VALVE LASH WAS SET TO 0.015 IN. FOR EACH VALVE. THE CAM VALVE TIMING WAS THEN MEASURED AND HAD TYPICAL WEAR CHARACTERISTICS. INTAKE VALVE DURATION VARIED BETWEEN 229 AND 243 DEGREES. EXHAUST VALVE DURATION VARIED BETWEEN 222 AND 235 DEGREES. THIS SOUNDS TERRIBLE, BUT IN PRACTICE, THE ENGINE RAN BEAUTIFULLY WITH VERY GOOD LOW END TORQUE AND HORSEPOWER. I HAD NO PROBLEM DRIVING 50 MILES PER HOUR OR PULLING STEEP HILLS IN HIGH GEAR WITHOUT A RUCKSTELL.

THE MODEL T FORD ENGINE IS A MARVELOUS MACHINE AND WILL PERFORM WELL EVEN WITH A WORN CAMSHAFT. HOWEVER, IT IS NOT A MODERN PRECISION RACING MACHINE. THE ENGINE WAS DESIGNED AND PERFORMED WELL FOR IT’S ORIGINAL APPLICATION. THE ENGINE PERFORMANCE CAN BE IMPROVED TODAY BUT STILL HAS IT’S LIMITATIONS.

SETTING VALVE CLEARANCE

A NEW CAMSHAFT IS GROUND TO GIVE THE BEST PERFORMANCE AT A SPECIFIED VALVE CLEARANCE. A USED CAM WILL HAVE SOME ERROR IN IT’S GRIND DUE TO WEAR BUT WILL STILL PERFORM WELL WITH ALL OF THE VALVES SET TO THE SAME CLEARANCE. I KNOW THAT MANY OLD TIMERS WILL DISAGREE, BUT IN PRACTICE THIS IS TRUE, AS DEMONSTRATED BY MY 1913 ROADSTER.

WE THEREFORE RECOMMEND THAT VALVE CLEARANCE BE SET THE SAME FOR EACH VALVE WHETHER THE CAM IS A NEW CAM OR AN ORIGINAL WITH MODERATE WEAR. THE AVERAGE MODEL T DRIVER WILL NOT BE ABLE TO TELL THE DIFFERENCE IN PERFORMANCE AND THE ENGINE WILL RUN QUIET. HOWEVER, THERE ARE ALWAYS EXCEPTIONS TO EVERY RULE!

SETTING VALVE CLEARANCE NEED NOT BE A DIFFICULT CHORE IF YOU KNOW WHAT TO DO. FIRST, BASED ON WHAT YOU KNOW ABOUT THE CAM, CHOOSE A CLEARANCE BEST SUITED FOR THAT CAM. ANYTHING BETWEEN 0.010 IN AND 0.015 IN. SHOULD WORK.

THE CAM GEAR HAS 48 TEETH. THE CRANK GEAR HAS 24 TEETH. THIS MEANS THAT THE CAM GEAR TURNS AT ONE HALF THE SPEED OF THE CRANK GEAR. IF THE CRANK GEAR IS TURNED ONE COMPLETE REVOLUTION (360 DEGREES), THE CAM GEAR WILL TURN ONE HALF REVOLUTION (180 DEGREES). THE TOE OF EACH CAMSHAFT LOBE IS 180 DEGREES FROM THE HEEL. VALVE CLEARANCE IS ADJUSTED AT THE HEEL OF THE CAMSHAFT LOBE. THIS INFORMATION CAN BE USED TO EASILY SET THE VALVE CLEARANCE ACCURATELY.

IF THE CRANK IS TURNED SO THAT THE VALVE TO BE ADJUSTED IS SET AT MAXIMUM LIFT. ALL THAT NEED BE DONE IS TURN THE CRANK ONE FULL TURN (360 DEGREES) AND THE VALVE LIFTER WILL BE SETTING ON THE EXACT CENTER OF THE CAM LOBE HEEL. THIS IS THE POINT WHERE YOU SHOULD ADJUST THE VALVE TO THE DESIRED CLEARANCE.

THE PROCEDURE IS AS FOLLOWS:

NOTE: THIS PROCEDURE DOES NOT REQUIRE REMOVAL OF THE OIL PAN INSPECTION COVER AND WAS DEVELOPED TO MAKE THE JOB OF VALVE LASH ADJUSTMENT AN EASY CHORE..

1. REMOVE THE FAN, FAN BELT, VALVE COVER (S) AND HEAD FROM THE ENGINE. YOU MAY ALSO WANT TO REMOVE THE RADIATOR TO MAKE THE JOB EASIER.
2. MARK THE VALVES NUMBER 1 THRU 8 WITH NUMBER 1 AT THE FRONT OF THE ENGINE AND NUMBER 8 AT THE REAR. VALVES NUMBER 1, 4, 5 AND 8 ARE THE EXHAUST VALVES. VALVES NUMBER 2, 3, 6 AND 7 ARE THE INTAKE VALVES.
3. TURN THE CRANK HANDLE UNTILL NUMBER 1 EXHAUST VALVE IS AT TOP DEAD CENTER (MAXIMUM LIFT). YOU MAY WANT TO USE A DIAL INDICATOR TO DETERMINE THE MAXIMUM LIFT POINT. THE END OF THE CRANK PULLEY PIN SHOULD NOW BE AT APPROXIMATELY 11:00 O’CLOCK. PLACE A MARK ON THE CRANKSHAFT PULLEY TO IDENTIFY THIS POINT AS YOUR REFERENCE POINT.
4. NOW. USING THE CRANK HANDLE, TURN THE CRANKSHAFT EXACTLY 360 DEGREES. ( ONE FULL CRANK REVOLUTION). THE VALVE SHOULD NOW BE SEATED AND THE END OF THE CRANKSHAFT PULLEY PIN SHOULD BE BACK AT 11:00 O’CLOCK.
5. NOW, CHECK THE VALVE CLEARANCE OF NUMBER 1 EXHAUST VALVE AT THIS POINT. IF NECESSARY, MAKE ADJUSTMENTS TO THE VALVE CLEARANCE TO OBTAIN THE PROPER CLEARANCE. AFTER ADJUSTMENT, RECHECK THE CLEARANCE.
6. REPEAT THIS PROCEDURE FOR ALL FOUR OF THE EXHAUST VALVES,
(VALVES NUMBER 1, 4, 5 AND 8).
7. NOW, TURN THE CRANK HANDLE UNTIL NUMBER 1 INTAKE VALVE IS AT TOP DEAD CENTER (MAXIMUM LIFT). THE END OF THE CRANKSHAFT PULLEY PIN SHOULD NOW BE NEAR 1:00 O’CLOCK. MAKE NOTE OF THIS POINT AS YOUR REFERENCE POINT.
8. NOW. USING THE CRANK HANDLE, TURN THE CRANKSHAFT EXACTLY 360 DEGREES. THE VALVE SHOULD NOW BE SEATED AND THE END OF THE CRANKSHAFT PULLEY PIN SHOULD BE BACK AT 1:00 O’CLOCK.
9. CHECK THE VALVE CLEARANCE OF NUMBER 1 INTAKE VALVE AT THIS POINT. IF NECESSARY, MAKE ADJUSTMENTS TO THE VALVE CLEARANCE TO OBTAIN THE PROPER CLEARANCE. AFTER ADJUSTMENT, RECHECK THE CLEARANCE.
10. REPEAT THE PROCEDURE ABOVE FOR ALL FOUR OF THE INTAKE VALVES,
(VALVES NUMBER 2, 3, 6 AND 7), USING THE 1:00 O’CLOCK REFERENCE POINT.
11. THIS COMPLETES THE VALVE ADJUSTMENTS.
12. CHECK YOU’RE WORK CAREFULLY AND YOU WILL BE PLEASED WITH THE RESULTS.

I HOPE THAT THIS INFORMATION IS USEFUL AND WORKS WELL FOR YOU AS IT HAS FOR ME. PLEASE LET ME KNOW IF YOU HAVE ANY COMMENTS OR SUGGESTIONS.


Top of pagePrevious messageNext messageBottom of page Link to this message  By David_Cockey on Tuesday, May 08, 2007 - 08:47 pm:

Anthony, lots of information, more than anywhere else, about Model T cams on the Tulsa club website: http://clubs.hemmings.com/frameset.cfm?club=mtfctulsa
Look under "Technical", then under "Model T Cam Project". For information on the stock T cam including the answers to your questions go to "Cam Designs" then "Stock Cam".


Top of pagePrevious messageNext messageBottom of page Link to this message  By Lowell E. Spicer on Wednesday, May 09, 2007 - 09:50 am:

The only way you can degree your valves to piston travel is by valve clearance and i don't want valve clearance some where from too tight to maybe >040 thousands install a reground cam amd they will all come rite.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Lowell E. Spicer on Wednesday, May 09, 2007 - 09:56 am:

The only way you can degree your valves to piston travel is by valve clearance and i don't want valve clearance some where from too tight to maybe >040 thousands install a reground cam amd they will all come rite.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Lowell E. Spicer on Wednesday, May 09, 2007 - 10:01 am:

The only way you can degree your valves to piston travel is by valve clearance and i don't want valve clearance some where from too tight to maybe >040 thousands install a reground cam amd they will all come rite.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Anthony Bennett on Wednesday, May 09, 2007 - 10:22 am:

Thanks very much. Most interesting. Thought provoking. All this info will provide me with hours of raging argument I'm sure:-) I have a hankering to build a flathead T racer at some point and this just adds to the fascination. Two more questions from left feild then.

While Ive seen a chev four head on T using SU carburettors(two 1 3/4"dia) Has anyone ever used an SU carburettor on a standard model T? They're available in 1" or 1 1/8" throat I believe but being a constant velocity device I thought they might lend themselves to a low speed lugger like a model T.

Is it possible to use a gear diven HT magneto conversion with an impulse mechanism to help starting. (Any guess as to how much retard there should be built into the assembly before it will "fire")


Top of pagePrevious messageNext messageBottom of page Link to this message  By Darren J Wallace on Thursday, May 10, 2007 - 04:10 pm:

I agree with what Glen Chaffin says.I had my 1915 engine valves timed according to piston position using one of those timing gages the vendors sell.It ran just fine,plenty of power and low end torque,but quite noisy.It was almost embarassing to pull up to another T.After reading Glen's posting Tuesday night,and giving it much thought,I went out Wednesday night and re-set all the valves to .012" clearance.It didn't take all that long to do.I have modern stainless stell exhaust valves,aluminum pistons,and regular steel intake valves.
Here's what I found about my motor now:
1.It runs quieter.
2.It gets to 30 MPH with less movement of the throttle lever.(according to my speedo)
3.It idles at a much lower RPM
4.It starts/cranks considerably easier.
5.No more "clickety clack" of the valves.
6.Engine seems to have more general power.
I did my engine with the piston travel postion gage because this is how I did my '26 engine a few years back.It ran fabulous.But it also had a completely original Ford factory engine with cast iron standard bore pistons,and original valves & cam.I figured this is how I should have set the valves on the '15,and I now understand Mr.Chaffin's points.I do not have a reground cam in my '15 either.
I feel the effort re-setting the valves has greatly improved my engine so far.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Marc Ericson on Thursday, May 10, 2007 - 08:08 pm:

If one has the oil pan off, can they just simply look at the lobe for the valve to be adjusted and adjust the valve with the lobe pointing directly away from the lifter ?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Harris on Thursday, May 10, 2007 - 09:19 pm:

Forget piston position and just adjust the valve lash anywhere on the 180 degrees of the cam when the heal of the cam is touching the lifter. Sometimes when you get too technical you mess things up.

For over 180 degrees of the cam rotation you can get a good reading.

I didn't read all of the above posts but do you have adjustable lifters ?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kenneth H. Todd on Friday, May 11, 2007 - 10:55 am:

Quote "For over 180 degrees of the cam rotation you can get a good reading."
This is true ONLY if you have a good cam.
The lobes are not the only part of a cam that wears, a lot of times there is a low spot where the lifter hits just after coming off the lobe.
If you happen to adjust at this position you won't have enough clearance. This is probably why Glen says to adjust clearance exactly opposite the peak of the lobe.


Top of pagePrevious messageNext messageBottom of page Link to this message  By GLEN CHAFFIN on Friday, May 11, 2007 - 01:02 pm:

Correct Ken,there is no wear on the heel because the lifter never rides on it. Always use the heel, 180 degrees from the toe. This is exactly what the procedure I posted does. The whole procedure is quick and easy and you don't have to remove the lower cover to see the lobes. This is not rocket science, lets keep it simple. Even when I worked in aerospace I tried to keep it simple. It was the best approach everytime.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Darren J Wallace on Saturday, May 12, 2007 - 01:33 pm:

Frank,
Yes,I installed adjustable lifters in the '26 engine I rebuilt,and they were already in my '15.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark on Saturday, May 12, 2007 - 02:00 pm:

Here's a back yard question...since more often than not(in actual practice) an average worn cam still works pretty well though it has loss of lift, is it possible thats this loss of lift is slighty off set by the toe being rounded over and giving slightly more "full open" duration?


Top of pagePrevious messageNext messageBottom of page Link to this message  By GLEN CHAFFIN on Saturday, May 12, 2007 - 07:32 pm:

True Mark, the slight reduction in lift will result in a slight increase in dwell on the toe at maximum lift. Our computer analysis shows that this will slightly increase low end torque and horsepower and slightly decrease the same on the high end.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mack Jeffrey Cole on Wednesday, February 06, 2008 - 05:49 pm:

Ok,I have cast iron head valves with Ford stamped on the bottom of the heads.I want to set the clearance on them and I think the method Glen Chaffin has explained is what i want to try since I can print that off,and no special tools are needed.
So if .022-.028 was used for the cast valves in the early days,what would be right now useing Glens method? I would think nothing has changed about Glens method or the way cast iron heats so I am thinking I need to set them around .018 to .020 to make sure I am in the clear but not have them to wide.A little racket will keep me awake,so I aint worried about that.It is a T not a Mazarati.


Top of pagePrevious messageNext messageBottom of page Link to this message  By jack daron-Indy. on Wednesday, February 06, 2008 - 06:30 pm:

Set them 0.015 on the flats and don't worry about it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mack Jeffrey Cole on Wednesday, February 06, 2008 - 07:17 pm:

thanks Jack.
I have allways tried to treat a T engine as 4 5 hp Briggs L head engines inline.I kinda fiqured if 1 valve is open and the other is shut,I should be able to measure and set the clearance on the shut valve and adjust it.

I have been looking for info the past while on checking valve springs.I know they are cheap,but I wanted to learn and fiqure some.
The best I can tell,they are supposed be able to exert 20 pounds pressure on the valve.So I am thinking of useing the same method to test a clutch spring to test valve springs.Measure a valve spring with a valve closed,use that length to compare,put a spring in the press on top of the batroom scales and put 20 pounds under the needle and measure the spring.
And get 8 that are the same or real close from what I can tell.


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