Thread: Project Sebring GT Spyder

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Thanks. Glad ya'll are still following along.

I did run into one unexpected issue with the new heads. This is hot rod building and I should have expected something to pop up to throw a monkey wrench in the plan.

The old CNC heads did have bigger ports than stock, but they were not that not much bigger. The TF heads are quite a bit larger. My original plan was to run LS6 exhaust manifolds and they matched up with the CNC heads pretty well. I liked the tri-y design and they offered stock reliability. While trial fitting them to build a custom dip stick, I realized that the ports in the manifolds were visibly smaller than the exhaust ports in the TF heads. I could have ported the manifolds where they mated to the heads, but they have fairly long individual runners (for stock manifolds) that I can’t get to to open up.

I do have a set of long tube headers that a friend gave me to see if they would fit the car. They are for a 69 Camaro and I did manage to get them on the car during the initial fab work, but they were very tight to the frame rails at the collectors and one tube on the passenger side was close to that frame rail. I also thought that they hung down a little more than I liked. I really wasn’t wanting to run headers on this car, but they do fit the exhaust ports and I already know that they kinda fit the frame. I don’t think anyone will have anything on the shelf for a kit car that hasn’t been made in 25 years and never even came with an LS engine. So, it’s either make these work, build custom headers or go with the LS6 manifolds and live with the small ports. Looks like I’ll be running headers! The big issue is that I already have a complete exhaust system in stainless, the 2nd actually, and it looks like I’ll be doing at least part of a 3rd. At the very least, I’ll have probably have to put some bends in the collectors and dent the tube next to the frame. I may just whack most of the collectors off and use V-bands to attach some offset collector extensions. The length issue might be solved with some skid protection. I’ll just have to wait until I get the engine back in to come up with a solid plan.

I can’t find a brand name on these headers which leads me to think that they are Chinese knock-off parts. They are stainless of some kind, probably ChiCom 409’ish. The upside is that they do have very thick flanges, fit the heads well and they were free. Of course, it goes without saying, that the long tubes will be a lot better for power.





Here’s my fitment issue. The pics are from the build.




I’m pretty sure I can put some offset bends in the collector and cure this. Might not be the best for power, but that’s the way it works out sometimes.