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Author Topic:   Backfiring when I let off for corner,,,,,,,,,,,
wam24u
Dirt Full Roller

Total posts: 66
posted April 15, 2002 08:21 PM
What will cause my engine to backfire and pop pop pop when I let off the gas going into the turn. Not enough fuel(bigger jets) or is my timing? Thanks in advance.
Engine 355 13:1 aluminun intake 2bbl. 72 jets headers

ford5
Dirt Freak

Total posts: 298
posted April 15, 2002 10:46 PM
exhaust leaks at the head?

champ
Dirt Roller

Total posts: 18
posted April 15, 2002 11:01 PM
I had this same problem....I never really worried about it, I heard it's just unburned fuel coming out, but my car was bangin out about 1/3 of the way down the straits and then it finally would kick in and run smooth. Going into the turn it would pop like crazy....Just trying to fix my "bangin out" problem I backed the timing off a little bit and it fixed both problems. I don't know if it will help you but it's worth a shot...If I had to pick I'd pick the timing first, it's easier. If you have the patience just do one thing at a time...that way when it is fixed you will know what fixed it. Good Luck

WesternAuto17
Dirt Freak

Total posts: 248
posted April 16, 2002 08:59 AM
Start with timing, but is a 13:1 engine ever gonna like a 2 barrel carburator?

Where is the timing now? Are you using vacuum/mechanical advance? What's the total advance? 34 to 36 degrees of total advance is pretty standard, but the question is how to get there. You can lock it in at full advance or use the springs and weights to get to full advance by 3500rpm.

Good luck, but be careful, too much timing could injure that motor pretty quick.

wam24u
Dirt Full Roller

Total posts: 66
posted April 16, 2002 05:23 PM
I am running at 36 degrees. I am useing a lock plate made by holley that locks the weightposts after taking them off.

ford5
Dirt Freak

Total posts: 298
posted April 16, 2002 06:15 PM
wam24u.......... it only takes a small exhaust leak on your header flange to head to get that kind of backfire on decell, i think that is what is wrong, hope this helps you

wam24u
Dirt Full Roller

Total posts: 66
posted April 16, 2002 08:49 PM
I do have a small leak at the header flange, I was just worried a little cause a guy at the track insisted that I rejet, Said I was running too lean. But my water temp was 180* all night, so it can't be lean right? I always thought if it was lean you would have temp porblems.Thanks guys, Everyone is so helpfull,Like we should be, Racer's helping Racer's, the only way we will survive lol .

ford5
Dirt Freak

Total posts: 298
posted April 16, 2002 10:00 PM
BINGO!! wam24u,you just solved your own dilemma congrats lol

IMCAHobbyStock43
Dirt Roller

Total posts: 17
posted April 16, 2002 10:33 PM
Mine does the same thing not as much during the race but after the race wean I let off the gas after I pass the checkerd it pops like crazy what could that be? I run in Hobby Stock you have to have 2 barrol carb, does that matter?

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We miss you Dale #3 Go petty #43

[This message has been edited by IMCAHobbyStock43 (edited April 17, 2002).]

[This message has been edited by IMCAHobbyStock43 (edited April 20, 2002).]

Machinah
Dirt Forum Racer

Total posts: 79
posted April 20, 2002 06:58 AM
This problem could be any of the above. When this happens, I have found that most of the time it is due to not running enough back-pressure in your exhaust, thus leaning out the fuel mixture. If this is the case, rejetting, racing mufflers, or both of these can help. You don't want to burn a valve or piston.

As for the temperature remaining at 180 this may not be an indicator of a proper mixture. It may only mean that your cooling system is working great.

Your answer may not be simple. Check out all of the ideas here thoroughly to be sure to catch the problem. It may even be something that none of us have thought of yet.

Scoot
Dirt Freak

Total posts: 330
posted April 21, 2002 09:05 PM
I had a similar problem, I double checked my plug wires and had a bad one and also #5 and #7 plug wires were switched.

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Scoot
Smith Racing Team
870-365-5989

George Gilliland
Dirt Full Roller

Total posts: 57
posted April 22, 2002 01:41 PM
Another issue is if the throttle plates are not closed enough at idle. If this is the case you may need a slightly larger hole drilled in the plate. This also affects the throttle response down low.

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