1989 heads
Race Director
Joined: Feb 2004
Posts: 12,517
Likes: 19
I think it will bolt on without issue. The vette stuff did not use the newer bolt angle on the center 2 bolts. You will lose egr though. 89 heads get egr from the pass side exhaust manifold. 85 gets it from the egr port in the head.
Thread Starter
Heel & Toe
Joined: Aug 2004
Posts: 15
Likes: 0
Originally Posted by Pete K
I think it will bolt on without issue. The vette stuff did not use the newer bolt angle on the center 2 bolts. You will lose egr though. 89 heads get egr from the pass side exhaust manifold. 85 gets it from the egr port in the head.
Thread Starter
Heel & Toe
Joined: Aug 2004
Posts: 15
Likes: 0
Originally Posted by 65Z01
Of course you will need to install the center bolt valve covers; try Contemporary Corvette (link on my site) for a used set.
Racer
Joined: Aug 2002
Posts: 386
Likes: 0
From: Lancaster Lancashire
c3-shark.
The 85 intake should bolt straight to the 89 heads, they (Y-bodies) use the traditional sbc intake pattern. (obviously as Pete K wrote, they wont accomodate your internal egr system, so you may have to get a custom prom with egr delete. There are several ways around this I believe) If they don't bolt up, then you may have possibly an F-body intake where the centre intake bolts are at a different angle (but can be made to fit) or a previous owner has fitted vortec heads and a 'scoggin-dickey' intake which won't fit! If you have vortecs, they flow better than 113 heads anyway in standard form. You can get adapters to convert centre bolt valve covers to perimeter type, but by the time your finished it is cheaper to just buy some centre bolt ones. While I am writing this, I realise that you mentioned/implied that you had perimeter bolt valve covers. That sort of rules out you having vortecs anyway I suppose.
The 85 intake should bolt straight to the 89 heads, they (Y-bodies) use the traditional sbc intake pattern. (obviously as Pete K wrote, they wont accomodate your internal egr system, so you may have to get a custom prom with egr delete. There are several ways around this I believe) If they don't bolt up, then you may have possibly an F-body intake where the centre intake bolts are at a different angle (but can be made to fit) or a previous owner has fitted vortec heads and a 'scoggin-dickey' intake which won't fit! If you have vortecs, they flow better than 113 heads anyway in standard form. You can get adapters to convert centre bolt valve covers to perimeter type, but by the time your finished it is cheaper to just buy some centre bolt ones. While I am writing this, I realise that you mentioned/implied that you had perimeter bolt valve covers. That sort of rules out you having vortecs anyway I suppose.
Melting Slicks
Joined: Feb 2002
Posts: 2,699
Likes: 2
From: The Black Hole LA
The intake will fit, the bolt holes are at the wrong angle though, you can have a machine shop fix this issue for you though with no problems. You will need a new set of valve covers with center bolt holes. You could always hop on ebay and pick up a later model intake manifold for very cheap as they are not very desired. I sold my hole tpi intake of my '90 for like $120 (plenum, runners, manifold).
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by hz900
The intake will fit, the bolt holes are at the wrong angle though,
RACE ON!!!
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Instructor
Joined: Jul 2004
Posts: 137
Likes: 0
From: CT
Might also want to consider the change in CR going from 76cc to 58cc chamber heads. If 76cc heads give 9:1, 58cc would get over 10.5:1 assuming CR changes 1 point for every 10cc. Aluminum tolerates more compression than iron before preignition becomes a problem however. I've considered this upgrade several times but am unsure about the preiginition. LTx motors run higher compression but they have aluminum heads and reverse flow cooling.
Instructor
Joined: Apr 2005
Posts: 128
Likes: 0
Sb
The small block is the same bolt pattern
You may need to use your shorter push rods because you don't have a roller cam. If you are going to a larger CC head you will lose tons of power. If you cut the heads to raise the compression you need to cut the intake side to. But then you get into valve angle issues.
I run an 87 with aluminum heads
Manley flat tops forged pistons with two valve notches
4 lefts and 4 rights
I run them at zero deck height and 58 CC heads
plus a thin graphite head gasket
10.75 to 1 compression ratio
The horsepower this made was enourmous from the stock cast dished pistons.
i have a chip
528 lift SLP roller cam
ported heads
pro flow cut back sodium filled SS valves
total seal rings
the lower end was balanced blueprinted and aligned
no problems with detonation and it gets 28 - 30 mpg on the highway
Better milage than new
only 10 -15 in the city though
Maybe because i am kicking it down all the time.
You may need to use your shorter push rods because you don't have a roller cam. If you are going to a larger CC head you will lose tons of power. If you cut the heads to raise the compression you need to cut the intake side to. But then you get into valve angle issues.
I run an 87 with aluminum heads
Manley flat tops forged pistons with two valve notches
4 lefts and 4 rights
I run them at zero deck height and 58 CC heads
plus a thin graphite head gasket
10.75 to 1 compression ratio
The horsepower this made was enourmous from the stock cast dished pistons.
i have a chip
528 lift SLP roller cam
ported heads
pro flow cut back sodium filled SS valves
total seal rings
the lower end was balanced blueprinted and aligned
no problems with detonation and it gets 28 - 30 mpg on the highway
Better milage than new
only 10 -15 in the city though
Maybe because i am kicking it down all the time.
