backfire thru carb at 3000 RPM

So, have we nothing to learn from all of this? Surely something was wrong and now it isn't. What has changed to make it go away?
 
TexasJohn55 said:
So, have we nothing to learn from all of this? Surely something was wrong and now it isn't. What has changed to make it go away?
Click to expand...

First of all, not positive it is repaired. Secondly, I rationalize it by the car must me engineered to have the air cleaner on if you are going to free rev it at high rpms. When the backfire was occurring, I could close the choke plate some and make it go away, So by having the air cleaner on, it may be the same as closing the choke plate some? I even raised it on the hoist so the tires were clear of the ground and tried it in 3rd gear. At 3000 rpm, Speedo was at 72 mph and all was smooth.
 
I apreciate it that you are satisfied now,but like john said and for me too ,the Aircleaner can't be the reason.
Its the sign for that the Engine run like under Choke = too less Air= under Load and too rich,this constelation is fixing
many problems and noises.
Many customers told me : " you must 'only' wrench it a little richer and all is ok " .

On my Engine with 2 (front aav 1 ) strombergs on the compund carb manifolds i can accelerate the motor without problems to high revs and i
have only 2 very free stainless holley marine aircleaner/flamekiller on it.
Years ago for fun i had try my old oilbath air cleaner on it ,only on one carb,but i have only this single one,
a big differend, the engine feels like asmatic, now power , and yes the inlet of the cleaner was clean and wash out,
like after a great service.
You feel a less of power with the cleaner adverse without it ?
 
I found just now a topic in the aaca forum thats let me remember to your "problem"
there is a guy he told that he tryed new paper air cleaner in his car,it runs bad then with the oilbath aircleaner all was ok ...
maybe the original intake manifold is so bad manufactured that the engine is under revs faster than the intake runner could deliver the mix ?? :confused:

suggestions ?

read self :
http://forums.aaca.org/f165/paper-air-filter-question-367946.html
 
The conclusion is that the engine is running lean without the air cleaner. So either the air cleaner is restricted (dirty) or the carburetor needs adjusting to richen it up a little. OR there is a leak on the intake manifold or gaskets.
 
TexasJohn55 said:
The conclusion is that the engine is running lean without the air cleaner. So either the air cleaner is restricted (dirty) or the carburetor needs adjusting to richen it up a little. OR there is a leak on the intake manifold or gaskets.
Click to expand...

Yes,thats the same that i nomaly think too ..
 
I will definitely let everyone know how it drives and performs as soon as I drive it. Going to the mechanical shop next week for exhaust and alignment.
 
I feel your pain

I have the same timing chain spacing issue and posted a question a few minutes ago.

I think the setup looks best at 10 washers between the marks, but agree that is not what the picture shows.

I'm 64, and have some hair to sacrifice if needed.

My engine has not run in years.
 
It does sound like a lifter could be pumping up and holding an intake valve open.
Lean mx causes spitback also.

Adding the air cleaner will slightly richen the mixture, so if you are lean this could help.
 
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