1 one cylinder

mshmodela

mshmodela

Well-known member
My model A backfired yesterday at low speed... She made it home but was missing clearly. I pulled each plug and 4,3,2 look normal like shown in Les's blue book but 1 was fouled big time.. I've yet to do a compression test and a leak down test...Going to get the data on those... I suspect a sticky valve on that cylinder and will take listen with a machanic's stethoscopy too. Question is can a valve cover be removed if I need to do that to inspect the two valves?
 
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Sure just remove the dozen bolts and the valve cover comes right off. I might be that that particular cylinder is not firing due to shorting in the distributor.

Mike
 
Mike,
sorry to hear you have this issue, here are a couple quick easy first steps.
make sure your points are adjusted and clean
now that the plugs are out look inside the plug hole while you turn the motor and see if the valves are opening and closing. if you have a comp tester handy go ahead while the plugs are still out and see what you get.
if that goes ok clean them or if you have another set replace the plugs and retry. if your using the same plugs move #1 to a different cylinder just in case the plug itself is bad the problem will move to the installed cylinder.
now restart if the miss is still present lets short out each plug to determine which one is not firing and report
 
Mitch//pa said:
Mike,
sorry to hear you have this issue, here are a couple quick easy first steps.
make sure your points are adjusted and clean
now that the plugs are out look inside the plug hole while you turn the motor and see if the valves are opening and closing. if you have a comp tester handy go ahead while the plugs are still out and see what you get.
if that goes ok clean them or if you have another set replace the plugs and retry. if your using the same plugs move #1 to a different cylinder just in case the plug itself is bad the problem will move to the installed cylinder.
now restart if the miss is still present lets short out each plug to determine which one is not firing and report
Click to expand...

Like Mike states, do the easy things first.
 
Thanks, awaiting for a compression spark plug adapter... I should get it tomorrow and I'll get the compression numbers etc.. I was just thinking though that given plugs 4,3,2 looks identical and clean (insulator is still white on the W18 Plugs) those cylinders/plugs off the top of my head are likely OK, but #1 had a lot of oil.. This newbie/Model A laymen thinks the oil can come either from a stuck valve (backfire from gas hitting the exhaust --which I had) and or two sources both: the valve and the rings... I cleaned #1 plug put it and the others back and she started on the 2nd crack like a champ... No missing, so until I get compression numbers I'm hoping the rings are not the source of the oil.. Anyway, need more data to decide next step as not to make things worse by guessing but still just thinking about it...

Thanks Mitch and Mike

Video after the cleaning of the #1 plug...
https://www.youtube.com/watch?v=syHbqQwxPh8
 
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Before I went too deep into this I'd drive it for a while til your adapter arrives and re-check the plugs. FWIW
Paul in CT
 
If your not missing now your going to find that most likely the compression is ok. Do you have excessive blow by from the crankcase or oil consumption out the tailpipe?
 
My compression numbers are:
#1, 50lbs, #2, 50lbs, #3 49lbs, #4, 50 lbs..
stock head. I will say the tail pipe is a tad soothy. I looked in to #1 cylinder and as I've read on other theads some black deposits... I was thinking, If i put #1 to TDC the piston should be as high in the cylinder and the valves closed... If I put some kerosene in there at that point and let do its thing..then with a tube attached to the end of a 60cc syringe try to suck out as much gook as I can.... at least the top might be better for now..
 
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I think you are OK.

It is possible #1 plug fouled and with a plug not firing, that cylinder will pass a lot of oil.

As stated before, check the points. When the points start to close up, you can loose ignition output and you may pick up a miss. Once a plug does not fire, it can foul and not fire until it is cleaned.

Also as stated by others, I would drive it and you may find everything is just fine.

My opinion,

Chris W.
 
I don't see where it has been mentioned what sparklers you are using. Maybe they are a bit a cold and a switch to something a bit warmer might help.
 
Mitch,

Thanks I read your early post... been a crazy week on the home front aside from the model A issue.. Thank you for your help.
 
mshmodela: DO NOT PUT KEROSENE IN THE COMBUSTION CHAMBER ! ! ! ! ! !
(your post #8)
It's going to drain down past the rings, wash the cyls and get into the oil.
Run a hotter plug. You could try with the engine running at a fast idle MIST some water into the carb intake, that might clean some of the soot/carbon. Otherwise I wouldn't worry about it. JMO
Paul in CT
 
Here's the data: I have a modern distributor and the point gap is 0.018. And Paul understood on the kerosene thank you. I'm thinking that this may all be due to:

1) I drive city stop and go.

2) Short trips

3) I suspect from reading a few threads that a thermostat may help getting the engine warmer and maybe help it become cleaner; so I've order one and will see after a month or so what that will do... (pull plugs and see naturally).

It was also suggested I try to mist in small amount of water at the zenith air intake at somewhat fast idle to help clean out the carbon. (after I do a 20 mile long ride.)
 
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Chuck Sea/Tac said:
The water misting is the trick I heard about as well, although I personally have never tried it.
Click to expand...
I use to mist water in my 71 F100 with a 429 engine every month or two. Couldn't believe the amount of crap it blew out the first time I gave it a good dose of water.
 
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