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Knocking under accelleration on rebuild



Just finished a complete engine rebuild. Some of you may remember the problems I had. Only one problem left. Here's what I did in the rebuild (major components) on my 88 L-98

Bored .030 thousands to 383 stroker
Accell SuperRam intake
Accell Long-Tube Runners
Ported & polished plenum
Bosch 24 lb. injectors
Crane "Gold Race" roller rockers
Peformance Products HEI Coil.
Scat 383 Crankshaft, alum. pistons, clevite bearings, etc., etc.
Double Roller timing chain.
Ported & Polished heads
Hooker Headers
Billett Flyweel
Used L98 block, 4 bolt main
CenterForce 11 Dual Friction Clutch

Already had a 52 mm. throttle body, Flomasters, K&N, adj. fuel pressure, etc.

Got the rebuild done about 2 weeks ago, and am now through the break-in period. I had Jeff make a new chip before this rebuild. When I was finally able to romp on it a bit this week, I discovered some loud "dieseling" or knocking at about 3500 rpm. I called my builder and he said the timing was set at -6 degrees without the emc ?? connected, and that the timing advance was controlled by the PROM. I sent away to Mid-America where "Formato's Fasterproms. Inc. (www.fasterproms.com) is advertising a custom chip for Stage I, II and III. The first chip they sent me didn't work because Mid-America had not told them I had a stage III mod. engine. They sent me a new chip a couple of days ago and it would not work. It shut down the engine at 3000 rpm's, much like I would assume a rev. limiter would. My MSD AL6 has a rev. limiter set at 6000 at the moment.

I am thrilled at the performance of the rebuild, but I can't really say how it will do in a quarter, etc. because of the top end knocking or dieseling. Formato's is sending me a couple more chips with different specs to try out, but it seems like a hit or miss thing to me.

Any ideas?




I have an Ed Wright chip and no problems after rebuild.

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