I have a '87 IROC w/L98 TPI that I'd like to buy a set of corvette heads for. I've found brand new heads for just over $400 but they don't have EGR fittings. Does anyone know where I can find some with EGR fittings? Can I get a set from a junk yard that has fittings and what years of corvettes would be best to salvage from?

 

The '88-'89 vette heads have much better ports than previous vette aluminum heads. You will not find EGR fittings on vette heads becuase the vette has an EGR riser on the passenger exhaust manifold to the back of the intake.

Jeff

 

Worse case, you could also have the egr function eliminated from your chip.

 

No L98 Corvette heads have EGR in them, they werent made that way. If you need the EGR setup, you'll need to route the EGR like the Corvette does, which is how I did it on mine.

Jeff, this is the first I've heard that Corvette L98 heads are different from each other. What about the 90-91 heads? I thought they were all the same casting.

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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

Kevin, how did you route your EGR? Do you have any pictures? I really want to use corvette heads and would appreciate any help you could give me. Thanks.

 

"There are actually two versions of the Corvette aluminum heads. The first design '86 and '87 heads (casting number 128) used a standard exhaust port. Starting in '88, the nuewer head's (casting number 113) exhaust port ... was raised .100 inch and given a "D" shape that improved exhaust port flow. Keep this in mind when shopping for used 'Vette heads." -John Lingenfelter, On Modifying Small Block Chevy Engines

-Mark W.
'88 SC Camaro w/ 305 TBI

[This message has been edited by Mark305TBI (edited April 16, 2001).]

 

I live in Arizona, which has a yearly emissions check. This check includes a visual and tailpipe sniffer at idle and cruising speeds. Our tailpipe emissions standards are identical to California. I also have Corvette aluminum heads on my 305 TPI.

That being said, I installed the top of my engine as though the heads had heat riser passageways, i.e. the EGR is in it's original location with NO Corvette style EGR passageways.

I've run this way for about three years. First, I pass the visual check because everything is where it's supposed to be. Second, here are my tailpipe results from last June:

Loaded (cruise) readings:
Max Allowed Hydrocarbons (HC): 220 ppm
My Reading: 76 ppm
Max Allowed Carbon Monoxide (CO): 1.20%
My Reading: 0.46%

Idle readings:
Max Allowed Hydrocarbons (HC): 220 ppm
My Reading: 72 ppm
Max Allowed Carbon Monoxide (CO): 1.20%
My Readings: 0.34%

As you can see, I'm well below the maximum allowable limits. In the three years my car has run this way, I have set a Code 32 (EGR system malfunction) only twice. Each time was after driving at highway speeds for about 30 minutes. I used to get this code before my engine rebuild without these heads so I can safely say the heads are not what contributes to this error code setting. I have recently disabled Code 32 on my EPROM.

I can only conclude from my own experience that if anyone decides to use Corvette aluminum heads, the lack of EGR passageways should not be a concern, even in an emissions check state.

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Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
Former Paxton (6-psig): 12.57 @ 111 mph.
Former Paxton (6-psig) & former 50-hp nitrous: 12.04 @ 114 mph.
Current ATI D1SC (Initially 10-psig): Projecting high 11's.
Future ATI D1SC (15-psig): Gotta catch them pesky 26-psig boosted TTA's!!

http://willie.camaro-firebird.org/

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

[This message has been edited by Willie (edited April 16, 2001).]

 

Willie, is this a dyno test? I assume so, since you gave "loaded" readings, but our dyno test in Colorado also includes NOX values, which is the issue EGR addresses.

Or does "loaded (cruise)" just mean they run the RPMs up in neutral to the "cruise" speed?

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam and intake, World 305 heads, Hooker headers & y-pipe, 3" Catco cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" Hedders, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere w/open diff & slipping tranny. Daily driver while Camaro was being put together.

 

Yes.

The loaded readings are taken at a speed of 32 to 36 mph in Drive (or fourth gear on a standard).

Willie

 

Kevin,
Mark posted what I was referring too. They have really good prices on used vette parts at www.contemporarycorvette.com . They sell the later model castings for a good price. The best part is that they warrenty parts for 30 days. I have bought numerous things from them and they are in like new condition everytime.

Jeff