i get a loud engine knock (just 1 knock) on full throttle runs when hitting second and third. the engine is all stock and timing is set at spec for california car 6 BTDC. higher octane no help. 5.7 TPI w/700R4 problem ONLY happens at wide open and shift point just before or at red line. anyone have an answer without guessing???

 

A guess, I would say it isn't the engine. Bad motor mount, tranny mount, or anything else that gets stressed when you shift.

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350 with stealth intake, holley carb, 470 lift cam. 700r4 with .5 boost valve, vette servo, tci lock-up kit, B&M megashifter. Richmond 3.73 gears, powertrax locker, timkin bearings, synthetic lube. Custom 3 inch single into 2 2.5 pipes. 1 1/2 drop springs, 1 5/16 solid front sway bar, 1 inch rear bar, custom subframe connectors, custom LCA relocation brackets. Kobel ground FX, currant red metallic paint. Lots of other stuff...
82camaro

 

This is actually fairly common on our TPI cars. Glenn91L98GTA (or something, lol), has been looking for a way to compensate for this in the PROM, but beyond that all you can do is make sure eveyrthing is in top shape (good tune-up, all injectors are good, etc.) It wouldn't hurt to pull all the plugs and see if there is evidence of un-even mixture as well. You could have one injector that isn't keeping up, making one hole run lean and detonate when the moood strikes it.


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Ed Maher - Moderator @ The TPI & Carb Boards
92 Z28 Convertible - Quasar blue / Tan top
305 TPI A4 2.73 - 14.7 @ 93.6
Stock except ported plenum and dual cats
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die

 

I really think is sounds like a mount or something also.

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1991 Firebird
350 L98 (was a 305 TBI),T-5,Edelbrock TES and cat back,Accel manifold
NOS,subframes,jegster torque arm,MSD Digital 6
AFPR,Lakewood lcas
Hurst linelock,SLP cam (206 212 .480 .486),relocated battery,cold air,Hypertech chip,centerforce df,clutch
poly bushings and mounts
AFR 190s
Harland sharp 1.5 rockers
autopower rollbar

12.33 @ 114.83 juiced uncorrected

13.510 @ 102 non juiced uncorrected

 

sounds like a mount too, oe even, my car, the torque arm was loose and the rearend would rotate and make a similar sound

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1987 Black 305 TPI 5spd IROC, G92, 9-bolt 3.45, Lowered, Cat-back, Air Foil, Sub Frames, Huge sways.

AIM: IROC 5spd
http://www.geocities.com/chevy5spdiroc/87Roc.htm

 

it's not a mount. with a snap-on scanner hooked up, you can see the knock sensor activate for a split second telling me it is a engine knock. Ed Maher, thanks for your response. i also thought of that and did a injector cleaning service using our shops profesional cleaning kit. noticed big improvement in idle and shorter hot start cranking times but still had the knock. can i find the prom info you were refering to anywhere?? thanks to all who replied

 

Dude that's so mean. heh.




I'm going to venture to guess that it's the transmission mount. Put your car on ramps and look at it, it'd be fairly obvious.

As for the knock sensor, well... You can set that off by tapping the block with a hammer. Makes sense that you could set it off with the engine/tranny slamming back down on the crossmember after the torque caused it to twist up some.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

is it just a single knock or a constant knock? at higher r's the engine is under more stress, it **might** if all other things are find be a bearing just starting to wear out causing the knocking

 

I get the same thing, 3-4 degrees of knock retard at the track after I shift to 3rd, and 4th. But not when I shift to 2nd. I posted on the PROM board about it and they were no help either. My mounts are all 6 month old Energy Suspension.


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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH (2.10 60')
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
-=ICON Motorsports=-