Trans Am evil knock of death?
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Joined: Aug 1999
Posts: 158
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From: Fairfax, VA, USA
Car: 91-Trans Am-WS6
Engine: L05 350 - ATI 9psi
Transmission: Pro-Built:Street/Strip
Trans Am evil knock of death?
Well my previous <a href="https://www.thirdgen.org/messageforum3/Forum7/HTML/001557.html">problem</a> has gotten worse in the cold. It doesnt only happen at idle now, it happens whenever the engine is cold. A distinctive knocking or bonking sound that goes with rpm, and the idle is getting rougher by the day.
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Joined: Jul 1999
Posts: 17,268
Likes: 169
From: 51°N 114°W, 3500'
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Worse when the engine is cold is usually a bad piston. The aluminum piston has contracted when cold and is slapping around in the cylinder. Possible problems would be broken rings or even a stiff/seized wrist pin.
Start looking for a replacement engine or some down time to rebuild that one.
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Stephen's racing page
87 IROC-Z Pro ET Bracket Race Car and knocking on the SuperPro ET class
383 stroker (carbed) with double hump cast iron heads and pump gas
LS6 Big Block buildup now in progress
Best results before the engine blew up
Best ET on a time slip: 11.857
Best corrected ET: 11.163
Best MPH on a time slip: 117.87
Best corrected MPH: 126.10
Best 60 foot: 1.662
Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association
Start looking for a replacement engine or some down time to rebuild that one.
------------------
Stephen's racing page
87 IROC-Z Pro ET Bracket Race Car and knocking on the SuperPro ET class
383 stroker (carbed) with double hump cast iron heads and pump gas
LS6 Big Block buildup now in progress
Best results before the engine blew up
Best ET on a time slip: 11.857
Best corrected ET: 11.163
Best MPH on a time slip: 117.87
Best corrected MPH: 126.10
Best 60 foot: 1.662
Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association
Moderator
Joined: Jul 1999
Posts: 17,268
Likes: 169
From: 51°N 114°W, 3500'
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Depends on how bad it is and how many cylinders are bad. I'm currently doing a similar job at work on a 7.0 truck engine. Replacing 1 piston, pin and rod. New rod bearings, rings etc. The crank was ok. I honed out the bad cylinder to the max of .002 oversize to get rid of the scoring on the cylinder walls and add new crosshatching on the cylinder walls. We're still waiting for a new piston to arrive. If it doesn't fix the knock then the truck will get a new engine. It's cheaper than tearing that one down and rebuilding it.
I want the old engine if we have to change it. 7.0 liter (427 tall deck), 4 bolt mains and a forged crank.
The only way to find out what's wrong and what's required to fix it is to tear apart the engine. There's not enough room in the car to pull the oil pan and inspect the bottom end so it'll have to be pulled anyway.
I want the old engine if we have to change it. 7.0 liter (427 tall deck), 4 bolt mains and a forged crank.
The only way to find out what's wrong and what's required to fix it is to tear apart the engine. There's not enough room in the car to pull the oil pan and inspect the bottom end so it'll have to be pulled anyway.
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