MTFCA Forum

I am gradually losing power.. the hills I just so could make it over I now can't make it anymore...I checked compression, 30 - 20 - 20 -30. Put a bit of oil in number 2 and 3 and they went up to 30.my thought is time for new rings. My question is, can I pop the pistons out and put new rings in with the old cylinder walls ? Will they seat ? Or do I need to hone the cylinders ? Or what else would cause low compression ? I put new valves in half a year ago.. oh yeah I did check the valve gaps yesterday.. any advise would be appreciated..

You are now under what would be considered the low end for compression which is about 35LBS. With out knowing more about the engine, might be time for rebuild, more then just a set of rings. 30/20 tells me, it might just be pretty worn out. Yes if you were to put new rings in you would need to hone the cylinders. Cast iron or aluminum pistons and std or over sized? Besides valves, what other work has been done on engine. How about end play on crankshaft? Does it run on magneto? etc

I rebuilt the transmission and flywheel last winter at that time end play good , changed the values and adjustable lifters at that time because they were original 2 PC valves, runs fine on mag.. thought I might be able to get by with rings

Sounds like time for an engine overhaul. Not an expert, just a thought.

Check compression with the throttle wide open. Use the electric starter or crank briskly. As mentioned, honing the cylinders would be the minimum nneded to correct excessive ring/piston/cylinder wear. You need to determine cylinder taper and you will likely need to ream the ridge at the top of each bore. It's very likely that your pistons have some wear, and worn piston ring lands will defeat a ring job, as will skirt wear. If cylinder taper is well within recommended limits, I'd hone the cyliinders, ream ridge if necessary, and install new pistons and rings. I'd at least check the rod bearing clearance and condition also, and lap the valves lightly. One problem with doing this work with the engine installed is: How are you going to keep honing grit out of the crankcase? It can be done, but great care is necessary, just as great care is necessary when grinding or lapping valves to keep all extremely abrasive residue out of the engine. New pistons are cheap for Model Ts, and intalling new ones will greatly enhance your chances of getting a good and long-lasting ring job. Cheap gaskets are no bargain. Get good ones and use all care in putting the engine back together. You might want to consider having the head resurfaced and using new head bolts. Low compression caused by worn rings/pistons/cylinders is usually accompanied by excess oil consumption, blow-by, and oil leaks. The engine may emit excessive smoke, which usually has a blueish tint. Some things that might cause low compression besides general wear are: Excessively rich fuel mixture washing down cylinder walls, gum or carbon-choked rings, rings sticky from engine not running for extended periods, dirty oil, sour gasoline, or all three, or valve adjustment too tight, oil too thin or oil diluted with gasoline.

You might get by with a basic ring job and get good results. Once you've check the various possible causes of low compresssion other than rings/pistons/cylinders, only dis-assembly and careful measurement can tell for sure if honing and rings can be expected to give worthwhile results or not. If a re-bore is needed, there used to be boring equipment available that could bore a block in the chassis. I don't know if that can be done on a Model T or not. If you need a re-bore, It's best to pull the engine. Cleaning up the engine after an in-chassis re bore might be more difficult than pulling it.

My take on it, worth what you pay for it.

To fix it right, you need to go through the engine checking everything. Could get spendy pretty easily. If you plan to keep the car and do significant touring, this would be the way to go.

Does the engine smoke or use excessive oil? It may be the cylinders are not too badly tapered or out of round. If this is a Sunday ice cream driver with just light usage, you might get by by pulling the head, honing the cylinders and replacing the rings. Depending on usage, this cheap way out may last a good while for you. It's band aid at best but that is all some people might need.

walber wrote: ↑

Sat May 22, 2021 2:58 pm

My take on it, worth what you pay for it.

To fix it right, you need to go through the engine checking everything. Could get spendy pretty easily. If you plan to keep the car and do significant touring, this would be the way to go.

Does the engine smoke or use excessive oil? It may be the cylinders are not too badly tapered or out of round. If this is a Sunday ice cream driver with just light usage, you might get by by pulling the head, honing the cylinders and replacing the rings. Depending on usage, this cheap way out may last a good while for you. It's band aid at best but that is all some people might need.

Very good points. Esp the Ice Cream thing Not everyone needs a $3-5000 rebuild just to drive around a little now and then.

New valves 6 months ago, you were happy; now power is down and so is compression...
What method did you use to put in new seats in the block and marry the valves to the block? What was compression when you were done with the valve job.

You may want to think "rings", but if compression was good 6 months ago, then you wore those 90+ year old rings (that were acceptable (?) then) out in absolute record time. Don't get me wrong, the rings may be shot, but they didn't change that dramatically in 6 months.

A vacuum gauge on the intake would tell you everything you need to know.

As you probably already know, the 30 psi compression is on the very low side, and a sign of a engine needing a rebuild. The 20 psi in adjacent
cylenders two and three could be showing a bad head gasket, leaking compression and exhaust gas between cylinders. When you have the head off to check the valves also take a look at the head gasket for signs of leaks at the gasket from
the leaking hot exhaust gases.

Check bore taper even if no ridge is evident. I've seen bores with taper like a funnel and no ridge. The engine may have already been re-ringed on a tight budget several times. Even if you know the history, it could have problems due to overheating, poor oil quality, hard service, running in dusty country with no air filter, running on kerosene, etc, or repair work done long ago and now forgotten. Most Model Ts have seen a whole lot of history, and some of it has left its mark on many of them.

Keep it simple! Check/clean and gap your plugs before you do anything else.....

Re: "Keep it simple! Check/clean and gap your plugs before you do anything else....." // That's good advice, especially if the engine is losing power, but not showing multiple symptoms of bad rings. Check the externals first. It could be a loose pin in the throttle lever linkage, or the timer linkage may be going South. Some kind of restriction in the fuel system, brake problem, transmission band adjustment... or, as pointed out above, the head gasket leaking between cyliniders 2&3. That wouldn't necessarily allow water into the cylinders.

So when put the values in I dropped new stainless steel in the old guides, I ran fine so I didn't check compression..it really doesn't show other signs of bad rings, it doesn't smoke one bit, the head gasket actually makes the most sense to me... the more I think about it I didn't have the throttle wide open when I did the test. Sounds like I'm going to do some more testing... thanks for the advice, I'll keep you posted, it will be a few days till I get at it..

With a Model T, as slow as they crank over and with the plugs out, really does not matter how open or closed the throttle is. You are only pulling compressing air in one cylinder. I have done it both way and found it just does not matter one way or the other.

Your new stainless valves aren't likely to wear much, but the iron seats in the block might wear rapidly if they were not fit properly to the new valves. That would cause the valve clearance to become less, which might prevent the valves from seating. If your guides are worn, your valves may "rock" as they seat, which will cause more rapid seat wear. If you have a situation where the valve clearance has become too small, for whatever reason, the situation will rapidly worsen as the engine runs with the valves failing to seat fully.

I have never seen a ring grove in a T block. I don’t think you can use the absences of a ring grove to indicate the condition of your cylinders.

If you simply plopped new valves into the old seats, then your rings surely are not your problem.

So I'll ask again: what seat preparation did you do to the block, and how did you mate the valves to the seats?

Larry e rutt wrote: ↑

Sat May 22, 2021 2:18 pm

I rebuilt the transmission and flywheel last winter at that time end play good , changed the values and adjustable lifters at that time because they were original 2 PC valves, runs fine on mag.. thought I might be able to get by with rings

Why did you change the valves & lifters and thought you could get by without rings (assumed a typo above). Did you check compression then?

In-chassis boring equipment is still available; the problem is that it is pricey. A really good automotive machine shop might have one, but if you live anyplace except in a major population center, good luck finding a shop that has one. There is no reason why a T engine could not be bored in-chassis.

Wonder how many 10s of 1000s cars have had the cylinders honed in place? Most times when people are doing this, they are breaking the glazing on cylinder walls not resizing. While honing may not be the correct word, this is what many call it when doing this.

Anyone with a boring bar could set up in the car. But my goodnesses, how could you ever get it cleaned enough not to self destruct?. And what about the babbitt?

Scott Conger stated it correctly, the valve seats have to be matched/ground to the new valves in order to insure a good seal.
Ar t Mirtes

So to answer your question scott... I dropped new valves in old seats and lapped them...I replaced the valves because I saw they were 2 PC valves and the one was chipped..it ran fine , I didn't check compression at that time I haven't ever checked compression until now, ( I had no reason to ) I love to tinker with my T... it is a original 26 folder kids and neighbors love it... I have it 2 years and maybe put 500 miles on it is a mere guess...I was hoping not to spend thousands on it,, but maybe I need to.. I guessed at the rings but sounds like probably back to the valves... what would be the easies/ cheapest way to put a band-aid on the valve seats ??the guides seamed pretty good I thought ..

Just a couple of pics...

A lot of people have replaced valves and lapped them in with decent results. Start by checking the clearance of the valves in the guides. If the guides are overly worn, there is no good fix beyond reaming to the next size and valves with stems that match. If the guides are decent, hand lap them to the point of a good contact seat all around on both the valve and seat in the block. Then recheck/readjust the gap. It would be nice to have the tools and expertise to properly cut the seats in the block but not necessary for a limited use car. Still no sign of a major rebuild being necessary.

Sorry, just reread your post and saw that you lapped them so my comment here has no value beyond checking the clearance of the stems in the guides.

Ford used an unusual step in finishing Model T bores. The name for the process may be "Brinelling". It amounted to mechanically surface hardening the cylinder bores, and probably made the bores very wear resistant. Original builds also used wide, soft cast iron rings, which didn't wear very well, but were very easy on the bore surface. Very few model T engines today have the orignal bore intact and in good condition, and many of them have been through more than one rebore and have been equipped with "modern" rings. That said, I've seen wear ridges in Model A blocks, many flathead V8 blocks, and any number of other engines, including Y block and FE Fords, Chevrolet 6s, and others. If a ridge is present, it indicates bore wear is present. If a ridge is not present, it may indicate minimal bore wear, or it may be due to a ridge having been presnt and been reamed out during a previous rebuild. Measuring the bore will determine the true condition. Some bore wear is acceptable, but none is best. I have had very badly worn engines that ran well and had lots of power, but used absurd amounts of oil and were capable of laying down a smoke cloud a quarter mile long. A particular 389 Pontiac V8 in a '64 Bonneville convertible comes to mind... The car cost me $75.00. I had a million dollars worth of fun with it.

Cast iron piston top ring comes all the way to the top of the hole, aluminum without checking, within a nats ear. So there should be no ridge ring, bore would be worn all the way from top to bottom, generally more at the bottom because of the way the piston rocks going past center. Wearing the bore oval shaped. The bigger dimension being in line with rod travel.

Regardless, there is a brisk trade in oversize Model T pistons, even 100 years on.

If the bores as worn, you should notice the piston slap. If not, maybe .010 oversize (from marked on piston top) piston rings might work. Hone & fit/file to each bore. If that is your problem. What I dont get is the piece meal repairs. When I get a new T that has Issues pointing to lots of use, I go thru the engine/transmission completely. Once. Until I wear it out again.

NEWAY seat cutter,...no abrasive necessary.

Re: Losing power on hills: Maybe those kids are growing.....?

BobShirleyAtlantaTx wrote: ↑

Sun May 23, 2021 11:56 am

Anyone with a boring bar could set up in the car. But my goodnesses, how could you ever get it cleaned enough not to self destruct?BE6E6E90-F2FA-474B-9165-27CC302B7450.jpegE13EEFB0-7FC2-48B0-8332-0FF5E3C85831.jpegEB4D6728-5C98-4CCF-B583-46D9492F8E63.jpeg. And what about the babbitt?

I worked in a Ford dealer in the early 1960's. On several occasions we had cylinders bored in-chassis. Getting the cuttings out of the engine was not an issue. The machinist would mask the entire sealing surface of the engine block except for the cylinder to be bored. He would then mask the crank with carefully taped plastic. Before any masking was removed he would co over everything very carefully with a vacuum cleaner. We never had any problems.

Put a bigger magnet in your transmission screen and add one to your oil drain plug!

Mine's already got a whole bunch of magnets that get dunked in the oil to get all the shavings out! ATTENTION, FORDISTS! Is your flywheel fuzzy? Car won't start? You need Dr. Flux's Electro-magnetic Magneto Demagnetizer! Enjoy faster accelleration, higher top speeds, and up to 45% more miles per gallon! Installs in 5 minutes flat... no soldering! No messy glue, tacks, or screws!.................................................................... $9.95 ...J.C. Whitney & Co, Dept. DFDM, 1917-19 Archer Avenue, Chicago 5, Illinois

So... I took it apart this evening... intake valves look ok, intake not so much.. also I can feel ridges halfway down in all 4 cylinders... I guess that means rebuild job, right ?

It's good you pulled the head to look. I'm not an expert, but those exhaust valves look like they were very hot. Maybe something happened to cause the ignition timing to back off. That would cause the extreme heat and a definite lack in power. Plus... after that happened they probably weren't sealing well either. So when you get it back together, I'd double check the ignition timing. Bill

It means the valve job didn't take

you might have some scratches 1/2 way down the bore, but you don't have ridges. Nearly all old T motors have scratches...some even have gouges from wrist pins gouging them. In most cases, it is meaningless relative to performance and very often doesn't even result in excess oil consumption. I've replaced rods for guys who are determined to not spend a dime more than the price of a rod and a couple hours of work...in most cases, even the gouged cylinder jobs ran passably well.

Proponents of valve grinding paste not always, but very often end up wrecking new valves and ironically never fully clean up the block anyway, and are the primary recipients of hardened seats and a full rebuild...if they had used a NuWay set and done the job (which does NOT require a finish grind), there would be far fewer "sunk" valves and far fewer hardened seats sold.

You may very well need to have the motor completely rebuilt, but there are plenty of folks who could put that thing back on the road for another 5 - 10 years with very low risk. Unless you have a burning desire to spend $4,000 - $6000 bucks on a rebuild, find one of those folks.

Yup! Neway seat cutter,...no abraisive necessary!

If you really want a power drop...
https://forums.aaca.org/topic/363161-19 ... nt-2220793
Wonder if a Ford would have kept running that long?

I’m as cheap as anybody but those seats are really deep, I would consider hardened seats at least. Looking at the 1st picture of the block those look like 2 piece valves. I don’t recall seeing holes on new valves for seating. If your bores are good and not too egg shaped you may be able to hone and add Aluminium pistons & rings while you’ve got it apart. That said, to consider the above, your rods need to be good and still have some shims left on them plus find the right sized pistons if you’re already running oversized stock pistons. Cheap however isn’t necessarily inexpensive. Good luck.

So how much wiggle in the Valve guides is functional ??

You want minimum wiggle in the valve guides. I don't know the spec, but the fit of the new valve stems in the guides needs to be within specification. Keep in mind that specifications assume that the guide and valve stem are in good condition and free from irregular wear. Worn or oversize valve guides could make a lapping job difficult, since the valve would not necessarily be held in line with the centerline of the valve port. That could allow lapping only a portion of the seat, rather than getting good contact with the valve face all around the seat. Your picture appears to show a lack of running contact on part of the circumference of several of the valve seats. (Could be the angle of the photo) If that is the case, the valves will leak, and running the engine in that condition will allow them to leak more as running time adds up. If I was working on your car, and already had the head off, I'd check the valve guides for excessive wear. If they're OK, the next step would be to re-cut the seats and grind the valves lightly and then carefully lap them in to a good fit, then carefully adjust the valve stem to pushrod clearance. The piston/ring/cylinder fit is another issue. But if you have not been using a lot of oil, getting blue smoke from the exhaust, blowby from the oil filler with the cap off and the engine running, and excessive oil leakage, your low compression readings could easily be due to valve issues rhather than ring issues. I'd want to check for any evidence of head gasket leakage, too, especially between cylinder # 2 & 3.

I bought a '63 Cadillac convertible off an old guy once. He said it ran, but used some oil. It did run, sort of. I was able to get it started and drive it home. It knocked and ran very rough, with some smoke, and a dead miss. It was getting overheated by the time I got home. I let it cool down, then checked the oil. It looked like brown gravy. I checked the radiator... no water. I got a hose and tried to fill the radiator. It seemed to take a lot of water. I looked under the car and saw no leaks. Then brown gravy-like oil started coming out of the oil filler cap/breather, followed by a healthy flow of clear water. It was clear to me that the engine needed service. I pulled the spark plugs and ran more water into the radiator. Water flowed freely from the front plug hole on the driver side. I pulled the head on that side and found that the head of the piston was cocked in the cylinder and no longer attached to the rod. Removing that revealed that the skirt of the piston was gone, and that the rod was severely bent and the wrist pin had knocked a rather large hole in the cylinder wall. I bought and installed a junkyard engine that turned out to run pretty good for $75.00 and enjoyed the car for a couple of years with no further issues.

Pat - NEWAY youtube says cut new seats but NO abrasive necessary! .....seems a very nice way to cut seats to me!

....some ov my comp won't type,....very poor in my response,....sorry,....???

"So how much wiggle in the Valve guides is functional ??"

Larry, the mtfca Engine restoration book (pps 47-48) states original new valve stem diameter 0.3105-0.3120", Valve guide holes, new engine, 0.3125".

Valve guide clearance for Inlet valve stem when new-0.0020 to 0.0035", exhaust valve stem clearance new engine-0.0030-0.0040". Acceptable valve stem clearance for running, ex & intake clearance-0.0060". Max worn valve stem clearance requiring repair, Intake 0.0080", Exhaust clearance requiring repair-0.0090".

The 'book value' for guide hole diameter, valve stem diameter and valve stem clearance in new engine does not agree, but I believe the clearance values do quantify the amount of acceptable 'wiggle' you are seeking. jb

Ok. I ordered oversized valves, and the reamer to go with it..my valve guides I can easily slide a 21/64 drill bit in the guides with a little bit of wiggle but I cant get the 11/32 bit to go in....according to me and Google that would be about 20 thousands... TOO MUCH wiggle.. so I'm gonna put oversized valves in ,and try seat em good, and see if I can push the rebuild off a few more years... I'll try to let you know how I make out... thanks for all your helpful advise..

Larry, I'll warn you that if you simply run a reamer down the hole without fixturing the reamer dead center on the valve hole (or where it SHOULD be since the last set of valves were lapped in with excess wobble/clearance), and then CUTTING a new valve seat, you are not going to come to a good end.

There will undoubtedly be someone who will cheerfully suggest that "nah, you only have to whale-away at the block with a couple of stones after you've reamed it and you'll be fine". If you take that advice, well the advice was free, just like mine.

http://www.mtfca.com/discus/messages/70 ... 1510948496 shows how I do it, and how others do it similarly, as well as a period tool which did the same thing as I and others do. All good engineering practice and you're guaranteed concentricity between the valve guide and the valve seat (which is absolutely vital once the guide/valve tolerances are back in spec).

I really cannot too strongly suggest that you get help with this from someone who is acquainted with this type of work. Pretty sure I said the same thing when you were first replacing the valves and sincerely hope that you will take the advice now.

So I got a valve job done, with what I am happy with.. compression is between 35 and 40 in all cylinders...car starts easy, idles nice.. However I still seem to have an issue with power.. Here is some info, see what you think...number 2 and 3 cylinders seemed to have burnt valves, as in running lean, when I start the motor and adjust the fuel I go clockwise to lean, (which is about one turn out) then turn counterclockwise to to get more fuel I can turn all day little or no change( 3 or 4 turns ) is that normal ? I thought I should be able to flood the thing ... I have a rebuilt holley vaporizer.. any suggestions ??

Does it have a new viaton needle & seat? These seats are drilled too small, compared to original. They dont flow enough fuel. That would definitely create a lean no power situation.
Pull the bowl & check for a black rubber tip on the needle. A proper hi flow version is available on the parts forum.
Being a vaporizer has its own possible issues. There are those here that like em, run em & know what to look for with them.

Larry e rutt wrote: ↑

Mon Jul 12, 2021 4:53 pm

So I got a valve job done, with what I am happy with.. compression is between 35 and 40 in all cylinders...car starts easy, idles nice.. However I still seem to have an issue with power.. Here is some info, see what you think...number 2 and 3 cylinders seemed to have burnt valves, as in running lean, when I start the motor and adjust the fuel I go clockwise to lean, (which is about one turn out) then turn counterclockwise to to get more fuel I can turn all day little or no change( 3 or 4 turns ) is that normal ? I thought I should be able to flood the thing ... I have a rebuilt holley vaporizer.. any suggestions ??

Aside the probable lean fuel condition, your compression readings are very low. I realize a 27 vaporizer motor has the least compression of all the T series, but, cant be that low. A stock blue printed Montana motor has 60#. I am saying you still have an issue there.

Is it possible to get dirt in the spray nozzle ?seems I'm not getting gas from the carburetor bowl to the cylinders...maybe I should tear it down and check it out

Larry e rutt wrote: ↑

Mon Jul 12, 2021 6:33 pm

Is it possible to get dirt in the spray nozzle ?seems I'm not getting gas from the carburetor bowl to the cylinders...maybe I should tear it down and check it out

Check the needle & seat, as I mentioned.

How did your rebuilt vaporizer get dirt in it already? Drain the carb bowl into a clean, clear jar looking for dirt. If you get a bunch, your fuel system needs a flush. Do the same @ the sediment bowl. It should have a built in screen. Unscrew the base. Look into the gas tank with a flash light for sediment & rust.

Will do.. I'll post my findings

Nice... I got my power back and then some... repair included, valve job, dirt in carburetor, spark plug wire to the 4th cylinder to close to the coil box bracket... now I can pull hills.. thanks for all the advice..

Larry e rutt wrote: ↑

Fri Jul 16, 2021 8:31 am

Nice... I got my power back and then some... repair included, valve job, dirt in carburetor, spark plug wire to the 4th cylinder to close to the coil box bracket... now I can pull hills.. thanks for all the advice..

Thats great! Now go drive the wheels off.