i have just removed the exaust manifold on my 76 280z and the head has been sleeved. the head has square ports but someone has sleeved it with round sleeves. what should i do and can you remove the sleeves and use the square ports?
Relax, its just the normal sleeving that belongs on all Zs of your year model.
The sleeves are there to promote fuel burning, reducing emissions. Some have ran flow tests after removal and report no real gain by removing them. I understand they can be removed, but it is very difficult to do.
A cool mod on this type of head is to remove the sleeve, same method as if you were going to port it, and "D" shape the port in the head. No real info as to increased flow but I've seen this done and it looks impressive. "D" the exhaust headers to match and you have something to show your friends and family!
I just removed the sleeves on my p79, and opened a can of worms. The port is so rediculously huge- a bit bigger than 1 5/8" across, as compared to the much smaller intake (probably not a good thing), plus behind the valve seat, there is a shelf that is created around the back side that the sleeve used to smoothe out ( other side of the valve from the port) and there is'nt a whole lot you can do to smoothe that out, I've been trying for the past two days. Plus once you start pulling those things, there's no putting them back in, they are mangled. I suppose the propper way to do this is to fill all those gullies and smoothe it out, but that may be extremely expensive. Also, there is those little bumps of aluminum that are difficult to get out, as well as places on the sides of the port that protrude under the head bolts that are no fun to grind out, but my problem is probably more that I can't find any 1" sandpaper drums to fit my arbour, and am using stones which plug up constantly. I'll probably break down and buy some carbides and have them forever. Anyways, gotta go, good luck with whatever you do, and is there anyone out there who has had ports welded, and how much did it cost?