This is TikiWiki 1.9.7 -Sirius- © 2002–2006 by the Tiki community Wed 21 of Apr, 2021 [07:07 UTC]

Forum: Hot Heads Tech Talk Forums->Hot Heads Tech Talk->331 hemi with backfiring problems [prev topic | next topic] murbas 331 hemi with backfiring problems i have a 331 hemi bored .040 over with 9 to 1 compression ratio, cam is an isky .485 lift 232 duration, 108 degree seperation, with dual holley 450cfm 4bbl's . headers are fenderwell exit with 3" collectors and baffles. car has a street/strip turbo 400 with a 3000 stall converter and 4.11 posi rear with 30" tall tires. i get backfiring occurring on ocasion under hard acceleration. can any help me with this problem ?   on: Sun 28 of Mar, 2021 [03:13 UTC] reads: 322 Posted messages Messages 10 20 30 All Style Plain Threaded Headers Only Sort Newest first Oldest first Score Threshold All 0 1 2 3 4 Find Top author message Webmaster Re: 331 hemi with backfiring problems on: Wed 07 of Apr, 2021 [16:42 UTC] score: 0.00 Murbas: Sounds like you're running too fat. According to the calculations I use, your 338 at 6,000 rpm will wants 587 cfm. Try a smaller carb and see if that fixes it. Have fun, Bob > i have a 331 hemi bored .040 over with 9 to 1 compression ratio, cam is an isky .485 lift 232 duration, 108 degree seperation, with dual holley 450cfm 4bbl's . headers are fenderwell exit with 3" collectors and baffles. car has a street/strip turbo 400 with a 3000 stall converter and 4.11 posi rear with 30" tall tires. i get backfiring occurring on ocasion under hard acceleration. can any help me with this problem ? author message hemistude Re: 331 hemi with backfiring problems on: Tue 06 of Apr, 2021 [19:47 UTC] score: 0.00 Is this a new build or has it been in place for a while and has run well in the past? Is it popping in the exhaust or through the intake? What does a compression check show? Is the vacuum steady or bouncy? Lots of clues can be had from those tests. Does the mechanical advance work on your distributor? Have you confirmed the base and full advance timing settings? It should at full advance by 3000 rpm. You can rule out vacuum advance as the culprit -- it is not in play under acceleration. If your full mechanical advance is between 28 and 32, then it shouldn't be popping because of SPARK timing. I always suspect VALVE timing next. Those "2 deg advance-straight up-2 deg retard" timing sets can be confusing to install. If that was set up wrong, it'll run but may give the symptom you are experiencing. Not necessarily the easiest thing to confirm but if everything else is right, that's all that's left. Don't ask me how I learned this. Hope it helps, Dave author message DaveBlakeman Re: 331 hemi with backfiring problems on: Thu 01 of Apr, 2021 [15:35 UTC] score: 0.00 Lean condition ,, leaky plug wires . Bent valve stem . Page: 1/1 Show posts: All posts Last hour Last 24 hours Last 48 hours

Login user: pass: [ register | I forgot my password ]