MTFCA Forum

Ok... I had my engine out and replaced the valves and rebuilt the transmission.. put it back and can't get any power out of the motor.. first I thought maybe my transmission was binding, but I've dont enough tests to rule that out..spark seems good, rebuilt coils, nice pink spark at the plugs. My instincts say compression because I replaced the valves, but doing the thumb test it seems like good compression... gas runs free at the bowl of the carburetor. When I short out the plugs, number 1,2,4 make very, very little difference if any. Number 3 does cause the motor to labor.it seems it's not getting sufficient gas, when turn the fuel adjustment I can turn it way far before any difference in the way it runs..is I have a Holley vaporizer. I had the bottom part of the carb apart found nothing. Is it possible to get dirt between the main valve in the carb and the cylinders??? Is it possible the motor is not grounded to the frame ?? What are your thoughts ?? Any advise would be greatly appreciated...

I'd be looking for an intake leak between the intake manifold & block.

Oh yes... I did drain the gas and add fresh non ethanol gas, made no difference... also have new brass ring type manifold gaskets.

Larry, I would probably start with a dry then wet actual compression test. See what the real numbers are and go from there.
Possibly recheck the valve adjustment...
Good luck !

If you can roll the car in neutral without the engine turning, or crank the engine when in neutral without the car rolling, your problem is not transmission binding.
I would suspect a problem with the valves. Do you have clearance on every valve when on the heel of the cam? What lifters do you have? If adjustable you can adjust to get the proper clearance. However if solid lifters, you would need to grind the valve stems to get the clearance.
A compression test would give you an idea of whether the compression is sufficient for the engine to run. It should be about 50 psi at sea level. All cylinders should be approximately the same. At higher altitudes the compression would be less.
Did you do anything to the timing gear? Are you sure the wiring between the timer and coil box is correct? You can get a good spark at the plugs, but if the timing is not right it would not run. Possible to have one cylinder timed correctly while the others are wired wrong? Anyway, these are the things I would suspect and test for finding the problem.
Norm

Thanks for the replies...I did file the ends of the valves to get .010 clearance...didn't do anything to mess up the timing..the motor starts rather easily...when installed new valves I just cleaned up the seats, and dropped the valves in and gave them a good whack with a hammer..was that a bad idea ??? Did I need to grind the seats ??

RE; "and dropped the valves in and gave them a good whack with a hammer" What? Valves rotate, so yes bad idea. Never have heard of doing that except for maybe fuel inlet seat. You could now have bent stems. As others have said, do a real compression check.

Should not need to whack. The guided should allow the valves to go right in but without a wobble. If you had to hammer them in, it's possible the valves are stuck open. Another possibility is that if you whacked very hard it bent the stems or made the heads crooked. This is where a compression test would tell you something about the leakage. A blow down test would tell you where the compression is low. You modify a a spark plug with a tire valve and with the piston at top dead center on compression stroke put about 50 psi in the tire valve stem and notice where the air leaks out. If it comes through the carburetor, an intake valve is open and if through the exhaust an exhaust valve is open and if through the oil filler hole, the rings are leaking. If you do these tests before you pull the head, you can eliminate a valve problem or prove it is a valve problem.
Norm

I think he was trying to "seat" the valve not having issues installing them.

if you replaced the lifters you had to remove the cam and so you would lose timing.
if you did not replace them your clearance is .010 plus what ever divet you had worn in the old lifter.
did you cut the seats and lap the valves? philip

I have & use my Neway seat cutter kit quite often and after bluing to verify full contact, I always give each valve a very slight "luv-tap" prior to re-assembly - been doing it that way for years !

Ok thanks... guess I'm guna hafta rig up my compression tester to fit my T... when I put air in the cylinders I couldn't get air to leak past, just pushed the cylinder down till a valve opened... hmmm

Alright I'm back at it...so my valve clearances were bad, really bad, 6 of the 8 were around .004.. so the question is ...is it possible to pull the cam replace the lifters in the car ? Or do I need to remove the pan and flip the motor upside down to install adjustable lifters ?

In any case you are first going to have to pull the valves/springs, keepers, generator, generator mounting side cover along with inspection plate and timing gear cover . The original lifters had a small hole in the side that a pin can be suck in to hold them up. You can lift them up and install a pin. If they don't have the hole in the side, see suggestions below for installing. After all are lifted remove the two bolts holding in the camshaft bearings and pull the camshaft out. To reinstall the lifters two easy ways, use o-rings to hold them up or as I did on the last one, really heavy sticky grease seem to work just fine. (Good strong cloths pins can work too for removing or installing)
One bit to add, the adjustable lifters are taller so the stems will need to be shortened some.

New valves are long...and you want to replace lifters?

Great thanks

How hard should I need to pull on the cam ?? Little bit of end play but I didn't really move it yet...

Oh.. I found another bolt...

Why are you removing your camshaft??????????? Why are you replacing lifters????

You need more valve clearance, so why wouldn't you just shorten the valves a bit?

Tops of the lifters are dished out...i could have tried filling them flat, but...I figure now is the time for adjustable lifters .. be easier to set the clearance...

Well, ok then.

Tomorrow's May 1, not April 1

I still don't get it.

Scott_Conger wrote: ↑

Thu Apr 30, 2020 9:49 pm

Tomorrow's May 1, not April 1

I still don't get it.

I’m unsure about why the valves are out of cylinder #3....the one cylinder that was firing.
And from the picture, the seats could use some attention.

I must admit,I do not understand the "whack with a hammer" thing on the valves,that would seem to cause more damage than anything else. Lapping them in is simple and makes sure there is a good seal.
The other detail I read that bugs me is the "pink spark". A good hot spark should be blueish to almost white.And very thin. Pink or reddish or wide in the small engine world means weak spark,poor combustion.

Sorry...my bad... I'm not giving enough information as I go here...I'll try and learn from my mistake...so the clearenes were all over the place, there must have been grud in the seats,including one being a valve being a bit short. Lifters are dished out seems its guna be pretty hard to get a good setting on the clearances..so I'm going to lap the valves, and keep the hammer away from em...put adjustable lifters in that will take care of my short valve stem, hopefully give me a better end result... thanks for taking the time to help out here...I restored alot of furniture in my time... but this is my first flat head motor, every other engine I tore down I would send the head to the machine shop...sure am enjoying myself...

i did the same valve replacement in my engine in the car. i used new non adj. lifters and trimmed the
valves but i was just being cheap the adj. ones will be easier. just pull the cam replace the lifters and
use clothespins to hold them. i have never used the adj. lifters i assume you do not have to trim the valves
if the lifter adjust short enough. i did a 3 angle seat to get the sealing seat real narrow and be sure to
lap them. dont smack them with the hammer. it should run great. philip

1. smacking new valves into old seats damaged one or more valves (even new, they should be reground at a good shop), so have them resurfaced
2. shortening valves is quick and easy. It is silly to go to the work of removing camshaft, lifters, buying lifters, installing them, reinstalling camshaft and then claim all that work was done to make the job quicker and easier
3. new lifters are in no shape to use as-is. A quality job always entails grinding both the cam face and valve flat, so there's another step and expense
4. expecting new adjustable lifters to be short enough to use any old valve is a bad assumption. More often than not, the valve will have to be shortened anyway...now won't you feel foolish for going to the work to put in adjustable lifters just to save the work of shortening the valves and THEN find you have to shorten the valves?
5. valve grinding paste is is undoubtedly marketed and sold by folks whose main job is to replace valve seats on ruined blocks. If you are really intent on ruining both the valve and seat, be sure to use grinding paste. If you want to do the job properly, cut new seats with a NeWay Cutter and end up with a proper, narrow seat at the proper location on the valve face.

If the lifters have divots in them the only way would be to do the piston travel method to setup. Trying to set by feeler gauge will not get anywhere if there are divots. In ether case, you will still need to adjust the stem length to set.
https://www.google.com/search?client=fi ... ton+travel

Larry e rutt wrote: ↑

Tue Apr 28, 2020 4:59 pm

Ok... I had my engine out and replaced the valves and rebuilt the transmission.. put it back and can't get any power out of the motor.. first I thought maybe my transmission was binding, but I've dont enough tests to rule that out..spark seems good, rebuilt coils, nice pink spark at the plugs. My instincts say compression because I replaced the valves, but doing the thumb test it seems like good compression... gas runs free at the bowl of the carburetor. When I short out the plugs, number 1,2,4 make very, very little difference if any. Number 3 does cause the motor to labor.it seems it's not getting sufficient gas, when turn the fuel adjustment I can turn it way far before any difference in the way it runs..is I have a Holley vaporizer. I had the bottom part of the carb apart found nothing. Is it possible to get dirt between the main valve in the carb and the cylinders??? Is it possible the motor is not grounded to the frame ?? What are your thoughts ?? Any advise would be greatly appreciated...

Not a great fan of the vaporizer carb. There is a plate inside it that "wears out". Mine did that and was running terrible. The guy I bought the car from had left an extra plate in the tool box that came with the car. 10 minutes and I was up and running. I have since put a "straight through" Holley on it.

Wow... installed adjustable lifters, lapped the valves, put it all back together..... runs like it should... thanks for all the help.

Excellent! Happy to read this!

The post just above this from Jerry V. should probably be the LAST post on this thread, but I'm gonna' throw in a couple comments that I hope might generate a bit of beneficial "discussion" that might be helpful for others doing valve work in the future:

First, I'm a great believer in the modern three-angle valve job for all conventional poppet type valve engines, old or new. Cutting new valve seats with carbide cutters like the Neway carbide valve seat cutting equipment will give you a very narrow valve seat which is VERY desirable! Model T valve springs are very weak, even when new, and that's one reason for the narrow seat,....more pressure which aids in tight seal. The old fashioned "lapping" with valve grinding compound (sometimes called "paste") with a stick with a suction cup on it was what "Farmer Brown" did because that method was "farmer cheap"! But every time an engine gets its valves "lapped", the seat gets wider and wider,....not good!

Second, whether you think so or not, even nowadays, most (if not all) auto parts store type machine shops where you take modern car engine OHV cylinder heads in for modern valve job, DO NOT lap valves at all! It takes time, a lot of time. And it's not necessary when new seats are "CUT", valve faces are trued up, or, more likely, new valves are installed. If machine shops then finished by "lapping" with valve grinding compound, not only does that take time, but the heads then need to be thoroughly washed perfectly clean, because even one remaining speck of that valve grinding compound is very damaging if not removed! Do you really think auto parts store machine ships take time to do this for what they charge to "recondition" cylinder heads? NO WAY!!!

Third, the Neway Company that manufactures carbide valve seat cutting equipment says that it is NOT NECESSARY to lap valves, and in fact, strongly discourages it in their valve seat cutting equipment user manual. Do you think Neway wants their cutting tools to gain a bad reputation because your valve job to turned out badly because you didn't finish the valve job by hand lapping with valve grinding compound? Neway states in their user manual that their equipment leaves a perfect surface on valve seats for valves to immediately break in to a tight seal when the engine is first started up.

Anyway, all that to say, you don't have to "hand lap" with the old suction cup stick, just because that's the way its always been done!

All other opinions welcome, however, for what it's worth,....that's mine,......harold

Compression test. Conpression test. Wet & dry. Read Jelf's "Ignorance" post. Once more ; Compression test.

I just had the same thing laped valves new exhaust manifold and aluminum intake new carburetor all new exhaust rewired NOS timer new plug wire to rewire the car and no power I found a intake leak was leak on the front port my friends said you have a valve sticking well no all have 45 pound of compression I replaced the intake with the stock one haven't had time to take it out yet but I think it's better