85 TPI heads vs. 89 TPI heads
Thread Starter
Joined: Oct 2002
Posts: 1,866
Likes: 5
From: Salem, NH
Car: 1999 Z28
Engine: LS1
Transmission: 4L60E
Axle/Gears: 3.23 10 Bolt
85 TPI heads vs. 89 TPI heads
i have an 89 TPI car and someone recommended i do bowl work to the heds whiles its apart. i was thinkin of doin the work to the 85 heads and swapin em out. the 85s are extremely low mileage. now heres the point of this thread, which set of heads is better? im thinkin the 89 but if they are the same or by some oddity the 85s are better, can someone let me know?
Supreme Member
Joined: May 2002
Posts: 1,512
Likes: 0
From: Tucson
Car: 1987 IROC-Z
Engine: 305 TPI
Transmission: T5
this is long to explains o I'll try to make it quick.
89 heads are center bolt and the center bolt pattern for the tpi intake is different than 85 heads.
85 heads are perimiter botl and therefore valve covers are cheaper.
I myself currently have center bolt heads of my car, but am porting and polishing perimiter bolt heads. all you do to have the intake fit is the pre 87 heads is modify the 4 center bolt holes on the manifold.
89 heads are center bolt and the center bolt pattern for the tpi intake is different than 85 heads.
85 heads are perimiter botl and therefore valve covers are cheaper.
I myself currently have center bolt heads of my car, but am porting and polishing perimiter bolt heads. all you do to have the intake fit is the pre 87 heads is modify the 4 center bolt holes on the manifold.
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, i meant difference in runners chambers etc 
