Slight backfire when taking off.
02-09-2009, 05:06 PM
#21
Le Mans Master
is it missing while it's popping?? you are now running 80 mainjets? what size did they replace??...if by going richer the problem seems better then you have a vacuum or slight coolant leak. if you drive it more and it gets worse over drive time, then this is a good diagnosis. you can go too rich and wash out new rings here.......
02-10-2009, 08:10 AM
#22
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is it missing while it's popping?? you are now running 80 mainjets? what size did they replace??...if by going richer the problem seems better then you have a vacuum or slight coolant leak. if you drive it more and it gets worse over drive time, then this is a good diagnosis. you can go too rich and wash out new rings here.......
02-28-2009, 08:27 AM
#23
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Backfire/popping at take-off
Well I believe I have exhausted (pun intended) every other possibility of the WON'T GO AWAY BACKFIRING/POPPING at slow take-off and lugging the motor in the 2,000-2,400 rpm from the RIGHT BANK only. Richened, leaned, sealed any leaks. No misfiring under acceleration or jerking when it pops. The plugs look great (except #4 plug) with the jetting changes and timing 14 degrees w/21 max advance (MSD mechanical) 4.11 4 speed and the tires will bark at you going into 3rd. #4 plug is turning black and flakey and looks almost wet fouled BUT fires (changed out no difference).
These are all the fixes I have tried, change timing, jets, float levels, double checked and sealed tunnel connection and manifold connections only to exhaust pipes (not mainifold to head gaskets) heat riser deleted, reset valve lash twice (dollar bill doesn't suck, just blows).
With the difference in the plug reading on that cylinder which appears to be getting worse I must have a slightly leaky exhaust valve???? or a bad seal on the head gasket and allowing collant contamination maybe???? BTW this was a new top-end kit w/aluminum heads new cam, carb, Torker 2 intake, bearings and cast iron rings. The only thing kept were the pistons and rods. Compression test 190-200lbs. Doing a leak down today just for grins and then take my little 355 mouse apart. At least it aint 70 degrees and sunny for another month.
I never knew how much fun a guy like me could have with my Vette and I still don't, LOL. If it didn't have wheels I swear it was a boat. I better be quiet it's listening to me now I KNOW..!!
Thanks everyone..!!
These are all the fixes I have tried, change timing, jets, float levels, double checked and sealed tunnel connection and manifold connections only to exhaust pipes (not mainifold to head gaskets) heat riser deleted, reset valve lash twice (dollar bill doesn't suck, just blows).
With the difference in the plug reading on that cylinder which appears to be getting worse I must have a slightly leaky exhaust valve???? or a bad seal on the head gasket and allowing collant contamination maybe???? BTW this was a new top-end kit w/aluminum heads new cam, carb, Torker 2 intake, bearings and cast iron rings. The only thing kept were the pistons and rods. Compression test 190-200lbs. Doing a leak down today just for grins and then take my little 355 mouse apart. At least it aint 70 degrees and sunny for another month.
I never knew how much fun a guy like me could have with my Vette and I still don't, LOL. If it didn't have wheels I swear it was a boat. I better be quiet it's listening to me now I KNOW..!!
Thanks everyone..!!
Last edited by obx2323; 02-28-2009 at 10:34 AM.
