Backfire followed by no fire

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Model T Ford Forum: Forum 2014: Backfire followed by no fire
Top of pagePrevious messageNext messageBottom of page Link to this message  By Dale Peterson on Saturday, May 31, 2014 - 08:04 am:

Was working with the 26 Fordor restoration today. Was running real rough and traced the problem to the carb. Spare Holley 3 screw for the 12 started and ran well.

Then after shutting down, tightening the inspection door on hog's head to stop oil leak, I just had to hear it run one more time. But, forgot to retard the spark and it fired backward. Now no more start, not even a pop. Pulled the timer and the flapper on the Anderson timer was bent down. Checked the timing and #4 was buzzing instead of #1. Did I just make an error on #1 position, or could the iron timing gear have stripped and ended 180 out? Or what else could have happened to cause no fire?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Garrison_Rice Minnesota on Saturday, May 31, 2014 - 08:22 am:

Is there a chance the commutator brush is 180 degrees off. But if it was that it would have had to be that way to begin with and the car wouldn't have run at all in the first place. With a backfire I start to imagine broken valves or bent lifters. I don't want to suggest broken crankshaft so I won't. The number 4 coil buzzing instead of number one is puzzling. Is there a chance you weren't on the compression stroke when you checked fire on number one? You also brought up that you're restoring the car. Has it ran good I in the past? Is there a chance you started with the timing gears a tooth off?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange on Saturday, May 31, 2014 - 08:25 am:

Check the indexing pin on the commutator brush, if the flapper got bent down, perhaps there was also enough force to shear the indexing pin, allowing the brush to rotate out of timing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Saturday, May 31, 2014 - 09:57 am:

Are you sure that both valves were closed and it was the end of the compression stroke on #1 when coil no 4 buzzed? Both pistons 1 and 4 will be up at the same time, but only one of them will be at the top of the compression stroke.

If you are sure #1 is in the right position, then check out the other 3 cylinders.

If the timing gear is broken, all the plugs will fire at the wrong order, or #4 will fire regardless of the position of the crankshaft.

My first suspicion would be that the flapper on the Anderson timer is damaged. You might try another timer if you have one.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Saturday, May 31, 2014 - 10:47 am:

Dale:

Has the flapper spring dislodged ? May have dropped out when timer was removed ?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dale Peterson on Saturday, May 31, 2014 - 11:53 am:

Flapper spring was ok


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dale Peterson on Saturday, May 31, 2014 - 12:00 pm:

This is the first running for me, but it was running well just before the backfire.

Mark, indexing pin was ok

Norm, will check to see if end of cam is turning tomarrow when I can get back to it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Saturday, May 31, 2014 - 06:03 pm:

180 out, just check to see if maybe you have a early cam? the pin hole will go right through, you may have fitted 180 after fixing the flapper.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dale Peterson on Saturday, May 31, 2014 - 09:55 pm:

Thought about that, Frank, no through hole.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Larry Bohlen, Severn MD on Sunday, June 01, 2014 - 09:17 am:

Dale,

Is the cam shaft moving when cranked?
I know it sounds silly but .....

Larry


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem on Monday, June 02, 2014 - 01:54 pm:

Dale,

I knew you were going to say it had an Anderson timer before I even read that far. At least for a while, and maybe still, the new Andersons were notorious for "catching" if the engine rolled backwards or backfired. Look closely at the timer itself for damage and also check out the timer rod for bending, as well as the spark lever to see if it's twisted.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dale Peterson on Monday, June 02, 2014 - 11:50 pm:

Larry, cam shaft turns fine.

Went out today, put flapper from spare timer on, opened the gas valve, and she fired right up. Guess I just bent the flapper and had it wrong as far as timing, so Mike was right.

Other problem, blush, forgot to open the gas valve after changing carbs.

I changed the carb from the NH to a spare 2 screw Holley and she now runs smooth. The NH is going to need some work.

For all you guys that run dizzy's, there is nothing like watching and listening to a T running on mag and coils like Henry made them. Well maintained, I think they can be every bit as reliable and much more satisfying as any modern upgrade!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange on Tuesday, June 03, 2014 - 07:34 am:

Glad you found the problem, hope to see some pictures of your project on this forum soon! :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Tuesday, June 03, 2014 - 07:44 am:

Dale,

Check the timing on all four cylinders. If an Anderson catches like that, it could well have bent one of the contacts in the timer itself, in addition to the flapper.


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