Ok, Ive got the manifold now. Its from an old Chevy RAJAY kit. Stamped on the side is R.V. Turbo 350. Port size and bolt holes match up perfectly, but theres a MAJOR problem. The manifold will NOT sit flush on the exhaust ports, as the upper log part of the manifold hits the valve cover rail on the head.

Now, Im using centerbolt heads... Im thinking that this manifold is for perimiter bolt heads only? Thats the only thing I can think of, because without about a 1/4-3/8" thick spacer between the manifold and the head, theres no way this is going to work. The guy I bought it off of is on vacation so Ill have to get back to him when he returns.

Also, the turbo is a RAJAY model# 3aa1ee10b1. Only thing Ive been able to find out about it so far is that the A/R is 1.0 and the flow map is very similar to a t40b.

Anyone?

 

I think that is about the same one I have. I shaved a little off of the manifold and then cut the valve cover to clear the manifold. I also used a set of copper gaskets to fill any gap left.

 

I ran into this when I swapped a 91 engine into my 86, the stock manifolds fit fine, but the valve covers didnt. I was able to get around it, but I think the ports are in a different location from the earlier heads.

 

Nope, the ports and holes are all exact. And there are no signs of any prior owners having this problem as the casting is totally unmarked, so Im thinking its because of the centerbolt heads. Can anone confirm the perimiter bolt heads are much different where the valve cover sits?

 

I've got a few sets of each in the garage, but I'm not sure exactly what you're looking for. Just looking them over there aren't any obvious differences in angles or anything... If there were there would have to be different headers to fit pre '87 heads in most chassis vs '87 and up, and I know that I've used headers off an '83 305 on a '93 LT1, all f-bodies got pretty much the same exhaust manifold design and all C4 'vettes used the same headers....

I believe that the valve cover rail is a little taller on the centerbolt style heads and the valve cover a bit shorter (ending up with the same overall height) to prevent oil leaks, but that would only make a difference if the manifold actually wrapped around then valve cover (which would make it difficult if not impossible to keep from the heat causing repeated valve cover leaks, and would require removing the exhaust to pull the valve covers)

 

hey 88 WS6 did you buy the complete rajay setup or just the manifold and turbo? I have a very similar kit sitting in the garage and would like to see some pics as you progress so when I do tackle it I'll have a little reference.
thanks,
Marc

 

I just bought the turbo and manifold. Ill get some pics tonight, as I dont think Ive explained it quite right.

 

If you have the Rajay RV version I've owned it hits the stock crossmember as well. If your is RV and does not hit can I get a pic? I tried fitment of one about 6 months back.

 

I know the bolt holes and ports are the same, what I meant was either the whole group of them is in a slightly different place (angle, distance from block, etc.) or the head is cast different and its closer to the manifold or the centerbolt rail sticks out further than the perimeter rail. All I know is the two dont really mix well because there is something very different about the heads in that area.

 

Well, Its just on the engine stand at the moment, but it looks like it will clear the xmember just fine. The crossover on the manifold is acually going towards the back of the motor... and yes, it is the RV series. How did it fit on your heads/what heads?

And Madmax, I think your right. Cant get pics at the moment cause they computer and camera dont like eachother... damn W2k3 server.

Ill probably just end up putting it on ebay, as Ive really wanted to design one myself. If this manifold did fit, I would have definatley used it, but its not worth the trouble of making spacers and such for an inefficient system.

 

Alright, heres a pic of the heads that my manifold WILL fit.


As I suspected, its made for the older style non-centerbolt heads. Notice that above the exhaust ports, the valve cover rail goes straight up, where the centerbolt style will angle out. While cruzing ebay looking for pictures, I came across them. Theyre from a '55 vette.

http://cgi.ebay.com/ebaymotors/ws/eB...category=33617

Heres the auction. Welp, looks like Im not gonna be able to use this damn manifold/turbo... off to eBay it goes!

 

Does anyone know if the older style L98 corvette heads are centerbolt? I have a set of the newer 113 D port castings, but I could trade them for the older style if they are perimiter bolt aluminum... doubt it though.

 

Like I was saying the manifold HITS the crossmember. It might look close on the stand but in the car close can be a long way off. Yeah it's made for perimeter bolt old style heads. You can use a couple of gaskets or spacer and get around that. I have considered gettting the up-pipe flange cut and welded back on at a decent angle or shortened. There's a large head repair shop that does work for major engine remans. They do cast iron and aluminum welding all day long. I asked them in the past about doing this and they said they could. Manifolds supply more heat to the turbo and dont tend to crack as much.

 

All of the L98 corvette aluminum heads are centerbolt.

 

I personally just cut a hole in the cross member.... it really isn't that big of a hole, or that big of a deal. Used a oxy torch first, then switched to a plasma cutter when I got ahold of them.