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92' Corvette LT1 change over to AFR heads

4K views 8 replies 4 participants last post by  SoCal805 
#1 · (Edited)
Hello!

I could buy AFR LT1 Eliminator heads with 180 cc intake 54 cc chamber for my LT1 engine. I already installed a GMPP hot cam kit, which I want to use with the new heads. The original valve covers are modified to fit the rockers. I still own a 52 mm thottle body.

Now there are some questions
Are the heads a good choice? A K&N air filter, hedman headers, Flowmaster mufflers are still installed.

Are there more parts needed?

Modifications to the chip of the ECM?

Thanks for any help in advance!!!
 
#2 ·
The AFR heads are a good performance head. I've used many of them over the years. I'm not sure what your performance goal is but I've typically gone to larger heads. The factory LT4 heads were even larger 195cc heads. The AFR full competition 195's flow pretty well.

The cam is decent for a factory grind but not the best choice for serious performance. It does have good street manners though.

You will definitely need a good tune for best results.

Also while it is apart, I would recommend upgrading to the '95-97 timing cover, chain & upgraded optispark. Lots of issues with the earlier versions.
 
#3 ·
Hello!

I had a call with AFR. They recommend the heads I could buy from another gearhead.
But they told me I had to use new pushrods. My understanding is that I could use the original ones, just like the modified valve covers ( modiefied because of the GMPP kit with rocker arms) and the headman shorty headers.

@ Lonnie P

Please tell me more about the installation. Thanks for any help!
 
#4 ·
The 180s are plenty for your needs they will run better than the LT4 heads even though they were bigger.

You can use the LT1 intake with them. If you use the comp ports youll need an LT4 intake GM $$$ or Edelbrock.

It will pull super hard youll be surprised, those lobes will last a long time. That fast ramp stuff just makes noise and eats parts far as Im concerned.
 
#5 ·
You need different push rods because the factory heads used self aligning rockers & the new heads have push rod guide plates that require hardened push rods.

You would use an aftermarket roller rocker designed for a Standard small block Chevy with large diameter valve springs. Some roller rockers are too wide to clear the factory center bolt valve cover bolts.

I've had good luck with the Crane rockers.

 
#6 ·
Hello!

I 'm using roller rockers from the GMPP Hot Cam Kit. They fit the original valve covers with some modifications.

Will they fit the AFR heads?

I don't want invest in parts, which were included at the hot cam kit, because the kit is nearly new.
 
#8 ·
Hello Lonnie,

the heads are installed!

I finished 4 weeks ago. Some minor problems. The header gaskets had the wrong shape for the hedman headers and I didn't noticed it. So I hear the leakage after the first start. Changing the gaskets is a displeasing work! After that I had a leakage at the fuel lines because I use metric plumbing fixtures with the stainless stell pipes of the fuel injections.
I used comp cams HD pushrods with the original length.
I drilled a hole through the BBK TB (the hole exists at the original tb, too) to get a better idle, but in the moment I have a whisling noise. I have to drill bigger or destroy the round shape of the hole.

The engine received a big change in its character!
Under 2000rpm you notice the increase of torque. At 3000rpm you could notice the will of the engine for revving, normally a LT1 starts at 4000 and not with such a torque behind.
A lot of fun to drive!
In the moment I finetune the programming with logfile-drives and the help from the guy in the US, who does the programming of the software.
 
#9 ·
Markus. The BBK TB often has a "whistle" sound from the blades not being machined as well as they should be. If you drilled the hole it should not be any larger than 1/8". If you have scan software for your PCM that shows IAC counts they want to be 32 (30-35) at idle with motor fully warmed up

To big of a hole and your IAC counts will be to low.

I have a stock 48 mm TB bored to 52mm so it does not have the issues aftermarket TB's have
 
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