31 s/w engine issue - help requested

brianpharmd

brianpharmd

Senior Member
Members,

I was hoping that I could get some input about an issue I am having with my 1931 slant window. When I drive the car, I am loosing power up small hills (slightly hilly area of North Carolina near Raleigh - not the Blue Ridge Mountains!). I am also having a hard time getting to maximum speed. Gas mileage has been poor and lately, the car dies when I come to a stop. Here is what I have checked so far.

Primary circuit - good blue spark from coil wire to head nut
Secondary circuit - rotor gap correct at 0.025" at all 4 points on the distributor body. Good spark from spark plug wire to distributor body.
Point gap - appears to have slipped to 0.016". Rest to 0.02". Rotated crank to ensure gap the same at all lobes on the distributor cam. No movement in distributor cam but some very slight movement in the upper distributor plate fore to aft. Checked movement on my 30 coupe and it has none. I will need to address this movement.
Timing - checked again after adjusting point gap. Used Les Andrews method and double checked with Marco method. The timing needed to be adjusted slightly.
Compression - For cylinders from radiator to firewall (90 lbs, 78 lbs, 90 lbs, 90 lbs). Cylinder #2 had the lowest at 78 while all of the others were the same. The readings were done with a cold engine.
Vacuum test - I posted a link to the vacuum test that I performed. I let the car warm up to operating temperature. The first part of the video shows the reading with spark advance down about 3 notches and throttled advanced to half way on the steering column. Around the mid point of the video, I move the throttle all the way up to bring the engine to an idle. Towards the end of the video I tried to capture the noises the engine was making at an idle. Not sure how well they came across. The way the needle bounces makes me think I might have a sticking valve, perhaps in cylinder 2?

https://www.youtube.com/watch?v=IIs_l9wxxvI

The spark plugs were pretty dark with carbon but not wet. Gas mileage has been poor. I am thinking I have a sticking valve issue as the gauge reading does not seem to drop below 15 which would then point me to a burnt/leaking valve. Is my diagnosis correct or based upon my descriptions/video could it be something else?

Fuel: The tank is fairly clean and there is good flow from the fuel line to the carburetor. Since the video, I have replaced the copper fuel line with a steel one and the Zenith with a side mount sediment bowl one. I opened the carburetor that was on the car and I did not see any gunk in the jets or wells. I have not tested my new fuel line/carburetor yet since the fuel line I installed has an automatic shut off tied to the ignition which I have not finished wiring. I was getting tired of having to always open and close the hood to turn off the fuel.

Thanks for the help/input.

Brian
 
Check your carburator filter and flow again you may not be getting enough gas. The low cylinder doesnt help
 
I would say the fluttering needle would seem to indicate a valve issue. Sounds like it might be a good test for the mystery oil.
 
What noises were you trying to video at the end? Are you hearing someting abnormal??
I wonder....crankshaft end play???
 
Check timing as follows directly: determine top dead center, mark crank pulley with a dot of white paint and put a white mark on timing cover. Take out all plugs then turn on ignition and see where the #1 plug fires, should be top dead center. Also check with timing light! Some on forum may poo poo this check but the two methods you mentioned are indirect ways of setting the timing. A direct check doesn't hurt anything.
 
can you post a link to the vacuum vid?
I did not see it first time around

Motor running hot at all??

Despite that you have checked the timing 2 ways I still suspect retarded timing. Did you account for the lash in the gears? If not, no matter the method it won't be right.
I agree with Mr Texas as to the use of a timing light if you are having issues; it can often speed up the diagnostic process especially if you don't work on cars every single day

Virtually every single Model A that comes into our shop is retarded, despite the owner telling us he has it timed properly. When we get done, the car has way more pep and the owner can't believe how well the car runs

Compression should be within 10% on cylinders and you are very close on that; I would not focus on compression.

Can you post a pic of a plug? That will help us to tell the burn

Is this a new issue? What work was done to the motor before this started.

And MMO in the gas is NEVER a bad idea to keep valves from sticking

BTW if every poster had the kind of detail you delineated at the outset we sure could help ppl a lot better
 
You seemed to have covered all the electrical issues, timing and point gap. I would concentrate on the carburetor. If you are running an original zenith you need to go through it and install a set of jets that have been flow tested. Once that is done you should position the GAv control to where it is cracked open from a quarter turn to a half turn and see it that solves your problem.

Tom Endy
 
RonC/Bruce - when I took off the copper fuel line that was on the car, the ferrules were more than 1/8 inch. With the new fuel line, I ensured they were set at 1/8 inch. I have to test yet as I had to leave NC unexpectedly to take care of some family issues in WV. Once I return to NC next week I can check the setup.

aonemarine - From the additional footage in the video, I was trying to capture the "fluttering" sound that was coming from the engine. I image it is the valves opening and closing but wanted to see if the sound was abnormal. Tough to bring across.

MrTexas - I do not have any experience with use of a timing light to set the timing. Do you have a link to where I can read how this is done with a Model A?

tbirdtbird - The engine was running hot before but that was due to the radiator being partially blocked. Now it is running around 160-170. Here is the link again to the vacuum video:

https://www.youtube.com/watch?v=IIs_l9wxxvI

This was a car that I recently purchased with input from some of the members of my local Model A club. A couple of them have worked on this car in the past with the previous owner. It had an engine rebuild about 6000 miles ago which for the previous owner was about 8-10 years ago. It had a valve timing issue that was addressed a couple of times by club members. I added MMO to the cylinders and valves before I ever ran the car. I also add 4oz to each tank of gas. However, I have only ran 1 tank of gas through the car since I purchased it. I will have to get a pic of the plugs when I get back home to NC. Right now I am in WV dealing with a family issue.

Thanks for all of the help!
 
to me the vacuum test vid clearly shows a sticky valve.
I would be sure to run MMO in the tank as you are doing. I would actually double the ratio for one tank (8 oz per tank) and put a QT in the crankcase (after draining out a qt of regular motor oil), and run the hell out of it. Yes it will smoke but who cares, You want it to get hot and let the chemistry of the MMO clean the deposits off the valve stem. Once the valve is freed up then you can change the crankcase oil.
I have been a mechanic all my life and have saved many an engine from sticking valves with this method.
My guess is the car sat a while and was not used, and that the PO did not use an upper cyl/valve lubricant such as MMO. This is nearly lethal with today's very dry gasolines.

there was a 'valve timing issue' This is a very different beast than an ignition timing issue. Would love to know what was done about it

BTW few here will know what a pharmd is, but I do
good luck
 
tbirdtbird said:
to me the vacuum test vid clearly shows a sticky valve.
I would be sure to run MMO in the tank as you are doing. I would actually double the ratio for one tank (8 oz per tank) and put a QT in the crankcase (after draining out a qt of regular motor oil), and run the hell out of it. Yes it will smoke but who cares, You want it to get hot and let the chemistry of the MMO clean the deposits off the valve stem. Once the valve is freed up then you can change the crankcase oil.
I have been a mechanic all my life and have saved many an engine from sticking valves with this method.
My guess is the car sat a while and was not used, and that the PO did not use an upper cyl/valve lubricant such as MMO. This is nearly lethal with today's very dry gasolines.

there was a 'valve timing issue' This is a very different beast than an ignition timing issue. Would love to know what was done about it

BTW few here will know what a pharmd is, but I do
good luck
Click to expand...

I went back through my emails from my club members and I found what they had done to the car. According to the club members, the car was having similar issues about 8 years ago. It ending up being the valve clearances were never adjusted on the rebuild. That is what I meant by "valve timing issue". I guess I used some incorrect terminology. So they were corrected and the car ran fine. I guess with it sitting as you noted, deposits have built up and are causing the sticking issue. In your opinion, if valve clearances are done correctly the first time, do they routinely have to be adjusted?

I will drain a quart of oil and add MMO to it along with the tank.

Yes, few know what a PharmD is. :D
Thanks!
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Some adjustable valve lifters won't stay put.It sounds like you have the same problem as before.It is something others have run into,I've only seen it once myself.A backed off lifter will hold the valve open,just like a sticking valve.It's still a stuck valve,it is just stuck open by the lifter,not gunk or carbon.I was given a set of single lock lifters by a fellow that said they wouldn't stay adjusted.I cheated,and made my own lock bolts for them.Actually I really just bashed the threads with a hammer.They've never been adjusted in the eight years or so they've been in my truck.
 
Agree with Keith.
Usually the adjusters stay put but sometimes they wander and you lose your correct lash setting. Removing the valve cover is not bad a job to recheck the valves.
I'd prolly still use the MMO treatment first and then if that doesn't work pull the side cover and check the lash. If the lash is off, spray a bit of brake cleaner on the threads and put some blue locktite on them.

BTW contrary to some advice given here, you do NOT need to pull the manifolds to get the valve cover off. Just yank the carb and have at it. Get the gasket ahead of time. Use Permatex Ultra Black gasket sealer; it is the best for the purpose. The blue silicone gasket maker will NOT stand up to petroleum products and will fail quickly.

Keep us posted
 
Also take a close look for a broken valve spring.I've heard stories about some repro spring problems,but again,not sure if that was real or just stories.I have seen a few broken springs that were pitted.When you said they fixed it a 'couple of times',that kind of tells me that there is a problem with the locks not staying in place.If you have the double nut locks sometimes the lock nut is below the top of the lifter boss casting.They may not have gotten them tight enough to begin with.
 
I have finished installing the new fuel line and side bowl carburetor. I plan to test everything later today if the weather holds. However, I need to add the 1 Qt of MMO and fill up the gas tank (adding 8oz of MMO there as well).

I also checked the accelerator and ensured it was working properly so that the throttle on the carb opened completely. There was a request by tbirdtbird to add a picture of the spark plugs. Please see attached. This is the plug from cylinder #1 but all 4 plugs look the same.

Thanks,

Brian
 

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Looks like it is running way too rich based on the plugs. With everything you have done to date, maybe clean them up and take it out for another spin. Pull the plugs again and see if they are still sooty black. You may just need to adjust the carb and GAV to get it leaned out some.
I don't think I see oil fouling, which is a good thing.
 
With the new fuel line and carb, the car has much more power now. I need to adjust the carb a bit but hopefully that won't be a problem. I added the MMO to the oil- 1 qt. I am guessing that with either the stuck valve or out of adjustment lifter, the MMO is burning in the cylinder leading to the horrible smell from the exhaust? I just don't remember it smelling that bad. The 30 I have does not smell this bad. Is this normal with MMO in the oil or should I be concerned?

Brian
 
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