VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 36 running rough 2nd act

Took a couple of deep breaths and went to it again. Put everything back the way it was at the beginning, and started fresh. Checked compression to eliminate suspecting a valve issue, everything looked good 107 to 105 psi for all 6 cyl. Found weak spark on # 1&2 cyl, I wasn't happy with the wires as they were hard and not the least bit flexible. Checked the plugs ( J12Y's are in there now, don't know what modern plug is suitable, have only 2 AC 46's ), they're clean and @ .32. Thanks to this site I was able to check the coil and found it not up to par. Primary showed 1.6 ohms and secondary showed 4200 ohms. Swapped it out with a later model replacement having a reading of 14000 ohms on the secondary. Plenty of spark now. Rechecked the timing, all good. Finally figuring that the coil was the root cause, fired her up and ....... no change. Idle fairly smooth and as soon as you open the throttle the miss starts and just gets worse. Retarding the advance 10 degrees with the octane selector doesn't help at all. At this point, I really don't know what else to look at. I keep thinking its going to wind up being something simple or stupid, and I'm to simple to see it. thanks to all, Bob

Possibly it is not getting a good supply of gas. If there are any filters in the lines or fuel pump clean or change them.

Fuel could be a possibility, Check pressure and filters!
Another thing to check is be sure the ignition point arm is
free on its pivot, and check the rubbing block, it could be
worn down (no lube on Distributor cam. Check point dwell with
a dwell meter; should be about 30 degrees if my memory is
accurate!I think fuel pump pressure should be 3 !/2 psi or
better. Could it possibly be something in the exhaust causing a restriction? Something could have crawled in there and built a nest! To check that, simply loosen the two nuts holding the exh pipe to the manifold!

F lip, thanks for your input. As it happens I have just gone over the fuel pump completely. New diaphragm, check valves were clean and not worn and all looked good. Back on the engine, pressure is good. Did check for a possible restriction in the exhaust also. The result of disconnecting the ex pipe was to have every neighbor out of their house to find what hell is that racket. Lets say this, the miss is much more noticeable with the exhaust pipe off the manifold. Until this issue with my truck developed, I thought I was pretty handy around engines, even though my background was with Detroit diesels. I was lucky to have found this site by accident and am amazed at the amount of knowledge and experience it contains. As I have said before I am completely stumped. To the point of putting a dial indicator on each rocker arm to check for a worn cam lobe. This is really going too far, but I'm ready for a fresh approach, as I've run out of ideas. Thanks to all, Bob

Did you try shorting out one cylinder at a time to try and see if its particular to one cylinder or not? Did you do a compression test as was suggested earlier?

Two other things come to mind. Are you sure the timing marks were lined when the engine was assembled? The other possibility is a broken valve spring.

If you are going to "do" the carb thing there are several "Filters" in the carb. These are located behind the plugs with the straight screw diver slot in then. Most are located viewed from the underside of the carb. These contain fine screen wire and will fill up with "dust like" particles. Mine had to be soaked in gas and blown clear with air. This can be on the "high" jet side or on the low idle jet side. Note: my truck sat 25 years before I dug into it....

To continue, I have already shorted out each cylinder at a high idle and found no change in how the engine runs, in other words, no dead or weak cyls. 345 chevy recommended loosening the dist. past the octane selector range, which I just tried. Advancing the timing makes it much worse, as retarding it makes the miss almost disappear. This was with the octane selector screw removed to increase the amount I could change the timing, without loosing the original timing mark. That being said I just had to pull the flywheel pan off to check that the painted mark was actually on the steel ball. It was, that would have explained a lot. I then decided to pull the distributer as I again was out of ideas. To go back to what chev gene had mentioned that I had the wrong distributer (# 1110008) from a 37 in the engine. I see now what gene was talking about, the oil pump drive is different, and its shaft is longer. So I have I believe a 36 207 with a later model gear type oil pump installed which would allow the 37 dist. to work, this is why the dist. is so close to the coil because of how it sits in the block. To refresh the block casting is #836010. I don't know if anyone has any info on the centrifugal advance curves or degrees on the 35 645G dist. vs the 37 # 1110008. I compared the mech adv springs on both dist. and found that the 37 dist has much lighter springs than the 35 dist. which would seem to me to allow more advance at a lower rpm. Can I switch the springs and weights, or does anyone have a 645T which gene says is the correct dist. Or am I grasping at straws now? Seems like I have way too much advance way too soon but can't figure why. By the way I have disconnected the vacuum advance for now as I sure don't need it. I'm not saying that this is the only problem, but it's narrowed the playing field. Thanks for your continued help and interest I really appreciate it ( and so does my wife, she wants this done so we can take a ride again). Thanks, Bob

I have a couple of used 645T distributors you can try, but if you don't have a 36 oil pump I don't know if they will help you out. If you are interested send me a PM.

Try the condenser.

I know just how you feel. I spent 3 months trying to figure out why my '36 was running so poorly.

To recap - It is either electrical or fuel. I always keep that "divide" in my mind. Once I start down one path, I try to STAY ON THAT PATH. Don't get distracted in your analysis efforts.

You said
Based upon these, and all of your other checks, I am inclined to think that it is on the FUEL side of the equation. Also, I'm inclined to think that it's easier to resolve electrical issues than fuel issues. Just my own opinion. And you seem to have nailed down the electrical issue (with the distributor still a last possibility).

Here's my tip or suggestion: When I finally resolved my problem, it was because I CHANGED THE CARBURETOR. This had the remarkable effect of changing many, many things all at one time. Three are SO MANY orifices in a carb that could be closed, partially clogged, or sucking air, that you can go crazy trying to narrow it down. Check them ALL with just one effort. Change your carb.

Borrow one from someone else if you don't have one. Or like I did, buy two more. Ouch -- but you know, it sure narrowed down the problem for me. It was in the carb. I cleaned the original, tweaked it, and rebuilt it. But it still ran like crude. Only when I changed the entire unit did I see an immediate improvement. Never figured out which area of the original carb was bad. Didn't care once I got a good one on it.

--Bill

Bill, thanks for your interest and support, I appreciate everyone's help. I've found that after composing a post many times I have evidently pressed a wrong key and am looking at a blank screen. That being said I thought I had mentioned that I took the W-1 off my great running DA and tried it, with the same results. That's 3 different W-1's with no improvement. I realize that doesn't mean that there isn't something wrong with all 3 carburetors. I should probably send one out to someone who specializes in these units, maybe someone can recommend someone from the vcca, so I can finally eliminate the W-1 as a problem. While I'm here can anyone suggest a correct modern spark plug replacement for the AC 46 or a place to pick them up at a reasonable price, installed now are J12Y champions ( I know, it's sacreligious ). Thank's Bob

Leagl, Thanks for replying about the 645T distributers that you have. My problem now is that I don't know how to send a PM. If you or anyone can help, I'd appreciate it. I can follow directions if their simple enough. As I've said before, I'm new to computers, and not smarter than a 5th grader. Thanks, Bob

To send someone a personal message (PM), click on their online handle (which is underlined - like mine Rustoholic) and choose SEND A PM from the pull down list. You'll be taken to a page where you can compose a subject and the body of your message.

Then, when someone sends you a PM, when you log on you'll see a flashing mail icon next to MY STUFF. Click on it and you will be brought to your message center. When you read the new message, the flashing icon stops flashing.

Cheers, Dean

"I keep thinking its going to wind up being something simple or stupid, and I'm to simple to see it."

Bob,

It is ALWAYS something simple on a mechanical device. The challenge is finding it. Every one of us who picks up his tools instead of the telephone to diagnose problems has been through it. When you figure it out you'll slap your forehead and say "That's what caused it?"

One of my race motorcycles, a 1974 Bultaco, acted like it was running out of gas each time I left the pits after getting my tank filled in a race. I was totally stumped. Then one of my racing buddies noticed that gas overflowing the cap vent was going down a long vent hose along the front frame tube but not exiting the hose, forming a vacuum in the tube and the gas tank that was starving the engine. Shortening the vent hose solved the problem.

Ane that's how it's always gone for me, always a simple problem but sometimes elusive to find.

Ray W

Bob,
I didn't see any previous mention of you changing carbs. (Excuse me if I missed that.) I would think that 3 different ones would have operated differently if the carb was the source of the problem.

And you mentioned that you "rebuilt" the fuel pump. Did you disconnect the line out of the pump and measure the amount of gas that it pumps? Or just put your thumb/finger on it and try to stop it's flow? (I'd prefer to disconnect it at the carb so that the line can be checked at the same time.)

If that works okay, then it's time... get ready... time for you.... to.... shift back to the electrical side of the equation!!!!

hi there,
I have been following this post with much interest.
Many and helpful replies to a difficult problem
My 2 bobs worth:-
have you considerer fuel starvation at the carburettor ?
it is a long metal line from the pump to the carbie, have you tested this for free flowing volume?
I experienced a problem with my 35 std with the fuel line from the pump to the carbie.
It ran too close to the rocker cover and as a subsequence the fuel was cooking before it arrived at the carbie.
The cure: I made a new fuel line , longer and extended above the rocker cover and also insulated it with a bandage of exhaust bandage.
Result: now more fuel percolation and improved running in very hot weather...

Just my 2 bobs worth mate!

To Bill, BlueyAU and all, here's the latest. Finally got a day off and figured with the nice weather I'd push the old girl out of the garage and work outside for a change as its not too hot. Last nite I removed the advance weights, springs and cam out of the 38 #111008 dist. that was in the truck ( yes, I know it's not supposed to work on this engine, but it does )and replaced the with the corresponding parts from a 35 #945G dist. My idea now having a centrifugal advance curve much closer to what a 36 207 engine was designed to use. To preface this, before pulling the distributor I brought the timing mark up to the pointer and the rotor on #1 cyl. So now I have a cleaned and newly lubricated unit with new points, ,etc.,etc. Not suprisingly it's in with no problem, and we're good to go. Start it up, sounds ok a idle, reset the timing ( it was almost right on ),Now its time, now that the engine has warmed up some, I reach over grab the throttle lever and run her up a bit, sounds a lot better, run her up some more and some of the roughness comes back, a little more throttle ( 2000 rpms ? who can guess ) and she starts to pop a little from the carb. I go back to idle and she's smooth as silk. I check the timing again, just to make sure that nothing has changed or moved? Shouldn't, and its on the money. For the hell of it I connect the vacuum advance up ( I had it blocked off, wanted to try just one thing at a time ) and like before it's worse. While I had the dist. out, I checked the vacuum adv unit for a vacuum leak and it's good, no leak. At this point, to avoid throwing a wrench across the street, after my lovely wife comes out to ask " How about we take the truck out tonite and go to dinner? " , I decide to break the news that's its not going to happen, unless we take her car. She's obviously handling this better than I am when she replies " no problem as long as we're going out. So ends this day, with not much accomplished. Again thanks to all for your help and sympathy, Bob

You might be to the point now where you need to take your vehicle to your mechanic so that he can check out the problem with an electronic analyzer.

Did you ever actually replace the condenser or rotor button? I have had a couple of rotor buttons fail but on inspection appeared perfect.

I have been following this post in depth and have a few ideas of my own about your problem.here are the possibilities I came up with:I feel you may have a weak,cracked or broken valve spring.I know you did a compression test and it passed,but,You stated as the rpms increase the problem gets worse.Doing a compression test is barely turning any rpms.There may be enough spring pressure to close the valves during this test to lead you to believe the springs are fine.Increasing the rpms with a weak valve spring would tend to not allow the valve to close in the proper amount of time.I feel it would be an intake valve spring,because you say it pops through the carb.This tells me the engine is firing when the intake valve is still open.Other thoughts are;Maybe you have a lifter hanging up,a valve stem hanging up,or a crack in the distributor cap which allows a spark to jump from one post to another.I would try to pull 1 plug wire at a time and run the engine(bring up the rpms).I suspect you will find you dont get the pop when one of the wires is disconnected.This is the cylinder I would concentrate on. Good luck

My condensor seems to go bad on me on my 35 with a 207 every so often I know when it goes bad because it starts to run rough like when I go to give it gas it boggs on me like if it isnt getting enough gas. I seen that several people asked if you changed it?

"There may be enough spring pressure to close the valves during this test to lead you to believe the springs are fine.Increasing the rpms with a weak valve spring would tend to not allow the valve to close in the proper amount of time.I feel it would be an intake valve spring,because you say it pops through the carb.This tells me the engine is firing when the intake valve is still open.Other thoughts are;Maybe you have a lifter hanging up,a valve stem hanging up,or a crack in the distributor cap which allows a spark to jump from one post to another.I would try to pull 1 plug wire at a time and run the engine(bring up the
rpms)."

To check Mike33's theory it is possible to remove valve springs without removing the head. To keep the valves from falling into the cylinder some guys push some 1/4" rope into the cylinder through the spark plug hole then manually turn the rotating assy to push the piston up, pressing the rope against the valves. Others trust compressed air to hold the valves tight against the seats. That's a leap of faith I wouldn't take.

A local professional mechanic I know sent a head to a machine shop for a valve job. Once the head was reinstalled the engine ran crappy. Long story short - one of the valve guide bronze bushings installed as part of the valve job was too tight on the valve stem holding the valve open. The machinist ran the reamer down that guide again and it was problem solved.

That's another example of a simple problem that was very challenging to identify.

Ray W

To Mike, Mario, Brino and all others, thanks for some new ideas. We're going to have some bad weather for a few days which will give me some time to continue my quest for a smooth running 36. Other than adjusting the valves at a low idle ( I'm guessing about 200 rpms ) I was reluctant to run the engine with the valve cover off at high rpm's because of the mess I assumed would occur. Maybe these engines don't have that much oil supply up top, I guess I,ll find out. Will try Mike,s suggestion to find the right cyl first before removing the cover. I can try another condenser later, as I was unaware that an engine would even start or run with a bad condenser. I do remember during my many valve adjustments that a few pushrods didn't rotate as I thought all should be doing but I did look for any to see that none appeared to be bent. Didn't know if that is necessary. Stinks that I don't have a pushrod cover gasket handy, but there's now other way to check the lifter springs. Thanks to all and have a great weekend, Bob

I checked my springs and was surprised to find that so many were not the same height. But these were the original ones. So after 79 years they had worn out! Ha. They just don't make anything like they use to. Just wore out to fast! There are parts collectors in the Club if you can not get a set from the vendors. Some are even in the original boxes. The look on the head shop guys face was priceless when I gave him all new springs in an original box! As you correct worn out parts you will find greatly improved performance.