I just put my 350 in not so long ago...and im having detonation problems, despite the fact that i use 92 octane. At first, i set the timing at about 8* and it would start to ping in the upper rpm range. So I backed it off a to like 5* and it still knocked. I decided to get the the MSD spark knock alert... i have my timing set to about 2-3* and the alert still beeps at me when i romp the pedal or go above maybe 3500 on a light or moderate acceleration. At this point, I dont hear the knock myself...but i do get a lot of engine vibration (i havent figured that out yet either) and i was wondering if that might set off the alert...it plugs into the stock knock sensor (i dont use it because im carbed) also, the motor was pinging like crazy one day and the knock alert wasnt even going off...Im trying to figure out if this knock alert sucks *** or if its the vibration or im just having a bad detonation prob. Like i said, I run 92 octane, Im using AC R44T plugs and it's probably an 8.5 compression w/ the stock heads...does anyone have any suggestions??? thanks

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350, Comp 262, Edelbrock Performer intake 600 cfm carb and exhaust, headers

 

I'm betting this is something basic. Have you checked your fuel pressure at WOT? Are the plugs and wires fresh. The vibration worries me- could a plug wire be burnt maybe? Have you done a compression check? Is everything MECHANICAL OK?

What distributor are you using? Read the article about HEI Performance in the tech articles section of the board and get an idle what a "correct" ignition curve for a typical small block Chevy looks like and compare yours to the article.

Basically, the knock is probably coming from either a lean WOT condition or over-advanace of the spark.

BTW- are you sure the timing marks on your harmonic balancer are correct? Sometimes if the balancer is on its way out the outer ring can slide around relative to the inner one, making the timing marks useless. Might wat to conifrm that TDC IS TDC.


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94 Firebird Formula M6- No options but Z rated tires. No mods over $10. 13.5@105.
79 Malibu "beater" w/junkyard 400 SBC, tweaked QJet 4bbl, finally a decent set of heads, a few other tricks. A maddening 13.000001 @ 108 on the motor with little traction. No nitrous runs with the new heads yet.

"One of the last remaining QJet tuners on Planet Earth!"

 

well im sure that the balancer isn't very far off if it's screwed up...i had the engine apart and it's definately close. i would really like to know about the vibration though, i think something isnt balanced right...u can see the flywheel/converter moving around quite a bit if u look under the car while it's running (i dont have the shield on it) i know it's not a burnt wire, it doesnt miss...the wires/plugs are new. im using an accel blueprint dist. and i dont know much about timing curve and how to check it, so ill probably check that article out...thanks