Aloha everyone, I was wondering if anyone knows any online resources for information on running the HSR in a C4 Corvette? The reason I ask is because I will soon be putting the aluminum 113 vette heads on my L98 (89 IROC-Z) and as long as its all apart I wanted to convert to HSR and change the cam. I've read the 87+ style intakes we usually use on our cars won't fit with these 113 heads. So I'm gonna need a HSR that has the correct bolt holes for these vette heads. I've read of people with Corvettes converting to the HSR, so I know its possible, I just cant seem to find any information about it on Holley's website. Do these heads need to be re-drilled? I've searched these forums, and google, and even a few Corvette forums but I still haven't found any good info. And along with that, I also have hood clearance issues which is common with the vette crowd. I've read someone makes a special plennum for corvette folks with hood clearance issues, so I'd also be interested in getting information on that. Appreciate your guys help!!!!

 

I think you just need to re-drill the center 4 bolts, to allow them to fit with the old style angle. bascially, stick a bit in the hole, and walk it over so that the bolt angle changes. There are supposed to be some type of angled shims too, I think that can be used to go either way.

Otherwise, I think they just bolt on.

 

Drilling as above is correct. I recently learned the hard way that the angles don't match up, and for the life of me, I could not figure it out at first. I thought the Maro intake was identical to the Vette, but I was definitely wrong.
Also, make sure you use the special aluminum head bolts and the new spark plugs for aluminum heads as well. I think most places specify plugs for Corvette Aluminum Head.

 

Hey thanks guys. Hmmm I was hoping I wouldnt have to drill/modify anything. Well thanks for letting me know. Anyone ever heard of that low rise plennum for the HSR? I found a link to it on these forums but the link no longer worked. Supposedly its the plennum the C4 guys have to use to clear their hood. Thanks guys!!!

 

Thunder racing had it I think.
I think it was a short run deal.
Try a search on Grumpyvette.

You could probably get someone to fab it up for you.
Not cheap over there.....

You can also open up the stock HSR plenum mount flange and sink the plenum over the base and weld the whole thing together.
Someone on here did it. Can't remember the screen name.

 

Hey thanks for the tip man!! I did search on his name and found another thread with more info!!

https://www.thirdgen.org/techbb2/sho...hreadid=160573

I'm gonna send him a PM and see if they still make this. Thanks again Z69!!!

 

Do those 113 heads have the 86 and older center bolt angles? My HSR manifold was drilled for both bolt angles....

 

Joby is dropping the plenum down on the base. Recently posted, I think in this forum. He milled out the bottom of the plenum and is going to weld the two together.

changing the bolt holes is no big deal, just need a drill and bit, and maybe a file for cleanup. the suckiest part is that the bolt won't sit flat after this, but you can put an angled shim under the head to make it prettier.

 

More about Joby´s projekt, in Swedish....
http://www.vetteforum.org/showthread.php?t=2930

 

There is kit that addresses the variance in angles
Bolt Kit for late heads (drop the 'HLY-" prefix for vendors other
than Summit) "HLY-90748 $59.99 Holley Intake Manifold Adapter
kit, Spacer, Bolts, Washers, the 1987-up design SBC"
Consists of 4 ea - bolts, circular washers, bev washers.

A search for 'square beveled washers' at www.mcmaster.com
will turn up similar washers in Alum and SS. But I believe you
might need to narrow them.

I believe that the newer manifold castings are drilled for both
styles. On request, I can photo a new manifold and post images.

For the English translation, try: My HSR modification

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