VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 engine problem(s)

I have just installed a 235cu. motor in my 36 pickup(Rebuilt)and have not been able to get it running correctly. It misfires when accelerating and has a severe loss of power. I set the valve clearances to specs, replaced the points, condenser and rotor and set the timing to the flywheel mark. Also checked the pushrods for straight and replaced the carburator all to no avail. Whats next? I'm out of options. has anyone got any ideas? Thanks....Richard :rolleyes:

Leak at intake manifold to head area - manifold alignment rings not in place.

Did you run a compression test on each cylinder?

I had the exact same problem occur on a 1931 Chevrolet engine once. The engine was totally "rebuilt" and when fired off it ran just like your engine. It turned out to be a bad head gasket. The problem could also be a vacuum leak as well.

:( :( :(

You should also lubricate the valve stems. Aim a stream from a WD-40 can at the stems as it runs. Most re builders do not give sufficient clearance in the guides and your springs may be weak.

Thanks guys for your replys; The head gasket is new and torqued to specs,I oiled the valve stems and sprayed oil around the gaskets for the intake manifold and found no apparent leaks, I know it's possible that the manifold could be cracked somewhere. I also took a compression check and the no. are; 1=110, 2=80 3=75 4=75 5=80 and 6=90, which I assume is because the rings haven't seated yet. Is that assumption correct? Keep the ideas comin. Thanks...Richard

Did you maybe set the timing to the TDC flywheel mark rather than the advanced mark?

Hi,

I am not at all impressed with your compression readings./

Try this: Put a spark plug in #3 hole. Take the compression in #2. Did it change significantly?

Remove the plug from #3 and place it in #5 and take the reading at #4.

From looking at the side of the engine where the head meets the block, can you see any metal or is it just a black substance? (Is the head gasket a composition or a REAL head gasket)

Let us know what you come up with.

Hi, I removed all the plugs and installed one in #3 and "Viola" the compression in #2 jumped to 150. Removed the plug from 3 and installed in #5,compression on 4 went to 135. The only thing that is visible between the head and block is the copper head gasket, couldn't see any black substance. So what do I have?, a blown head gasket? Whats next? Thanks again...Richard

There should not be a difference in the compression on the cylinders on a fresh engine - but - the 15 pounds would barely make a difference in the running.
Did you adjust the valves with the engine hot and running?... lubricate the guides as Ray mentioned (thru the springs) or pour a pint of Marvel Mystery Oil thru the caburetor with the engine at a fast idle.The head gasket would be the last thing that I would suspect with this engine.The compression would be much lower and if burnt between 2 cyls. there would be almost zero compression on those cyls.What is the compression on the other cyls? Does it idle smooth?.Squirt oil at the joint between the cyl. head and intake maniflod.Does it suck in the oil.smooth out the engine and cause exhaust smoke?
Didn't read the last 3 posts....valves too tight???Lossen valve on a low cylinder and recheck compression...lossen about 1/4 turn each.

As a note-the intake valves are the straight up and down ones - exhaust at slightly at an angle.

Hi Chevgene, I did spray oil on the intake manifold to head joints with no noticeable difference, no increase in rpm's or smoking. Also I have adjusted the valve clearances several times to no avail. and poured oil on the valve stems. The motor is hard to start( with 6 volt) When idleing it sounds good but when you increase the rpm's or put a load on it, it has no power and a severe misfire. I am getting fire thru all the wires and the plugs are firing, but if I pull the wires off one at a time it makes very little difference in cylinders #2 and # 4, but a significant change in all the rest of the cylinders....Richard

If the engine idles good but mis-fires when trying to increase RPM I would suspect your going lean on fuel ( vacuum leak, intake valve sticking, carb float sticking or needle valve sticking, etc. Another thing would be weak valve springs or late ignition timing (cam to crank timing.

Your new compression readings are as I expected. Gene, may be correct, but to me this does indicate a headgasket problem.

Befor we get carried away, check the operation of the vacuum advance. You can remove the line at the carbureator and by mouth suck on it. You should generate enough vacuum to make the distributor move. If it doesn't move, then you need a new vacuum advance.

If that procedure doesn't reveal a problem, the next step is to change the condensor on the distributor (Don't care how many times it has been changed, do it with still another condensor).

Red36
I like Ray dont like the difference in compression readings.
Another test you can do, use an old spark plug base without the porcelane and make an adapter to connect to a compressor.
Remove all spark plugs and put a cylinder at top centre compression put the vehicle in top gear apply park brake and if get someone to hold foot brake as well.Gently fill cylinder with compressed air.
If engine turns release pressure and recentre piston at TDC. Whereyou hear air escaping will tell you what is leaking, at carb means inlet valve, tail pipe is exhaust valve, oil filler is rings adjacent spark plug is head gasket, radiator fill is head gasket or cracked head.
Repeat for each cylinder. This is a crude type of cylinder leakage test but works.
Tony
Tony

Ok Guys, thanks, I will perform all these tests and get back to you. We're bound to find the problem sooner or later.....Richard

Have you actually had a timing light on the engine while it was running? In past years I have had both 235's and 216's run fairly well at idle but have all sorts of problems above idle if the timing is 180 degrees out or off a tooth. And, of course, this is after I was absolutely sure!!, double positive!!, cannot be wrong!!, that I had it timed correctly.

Hi Mike, yes I've had a timing light on it when running, I brought the piston to TDC on compression stroke and aligned the ball on the flywheel with the pointer on the bellhousing,w/light and even set the timing at different degrees and did not eliminate the problem, I'm going to try the other suggestions the guys offered and see what happens. I hooked up a vaccum gauge this am and the needle is in the green(18") at idle. thanks for your input. I'll keep you posted...Richard

How is your fuel pump output?? Still think your running lean at higher RPM.

35 pickup man, I don't think that the problem is too lean a mixture,as I am running an electric fuel pump and I have changed the carburator and taken it apart and cleaned it without any difference. I have performed all the tests suggested and have decided to pull the head and inspect the gasket for flaws or defects(warped head). Other than time involved total cost should just be for new gasket....thanks, will keep you posted...Richard

Have you checked the function of your vacuum advance, as suggested by Ray in an earlier post? If your distributor does not advance, you can get the symptoms you describe. Good Luck, I will "stay tuned" (no pun intended) to hear the final outcome of your quest.
Mike