Grinding on cast iron exhaust mani

[d510addict]

Well I've acquired a w58 head that should work to keep compression low enough on my lz20, but I've got a problem its a round port head and all I have are square port manifolds and my exhaust drop pipe will not fit the l20b manifold so I have a question. I've been looking at the alignment of the gasket on the head and the mani and it looks like I could grind at the manifold to keep the flow smooth would that be the wrong way to approach things? I've been checking around for a square port head but cannot find one that hasnt been milled/shaved.

 

Would I be better off just trying to trade this head for a u67 or can this work with a square port header?

 

 

I'm kind of stuck here the gasket holes match exhaust almost perfectly.

[wayno]

You can use the square port manifold on the round port head, it don't work the other way I beleave, or you could just go find a round port exhaust mani at the wrecking yards out of a 78-80 datsun truck. Maybe someone here has the correct one for you. I do beleave that your C/R will still be above 9.5, but I am not positive. Have you given up on the L20b rebuild with dished pistons? Did the engine run with the fuel injection before it was pulled apart? Do you still have, or ever did you have the wiring harness with ECU for the Z engine?

[wayno]

I did not see the photos when I read the post the first time, I beleave you should use the square port gasket though, it has been so long since I have done this I can't remember, but I do remember using a square port ex. mani on a round port head with no leaks for a while, I wouldn't do it long term though.

[d510addict]

I have everything for the EFI and the sorts but know nothing about getting the motor running with it all, as well as wiring. I didnt really give up on the l20b but it is going to run me 700 + in the machine shop which I don't completely mind but the LZ20 would have been cheaper.

 

I super frustrated with this though right now, I bought this head from skib like a dummy not realizing it was round freakin exhaust ports, and sounds like it is going to put me in the hole even farther to get it working. Should I cut my losses on this and sell off the stuff I have and rebuild the l20b?

 

Trying to be the intermediary is freaking blowing too

 

/end rant

[HRH]

Am I missing something, or can't you just go to the local pick and pull and grab an exhaust manifold off a 79ish 620 or 510 that has a round port head? Should bolt right up and there you go?

[datzenmike]

The round port manifold has a single large down pipe. That square port one is two pipe into a twin down pipe.

[HRH]

Okay, I missed that. Couldn't you cut the exhaust pipe farther down, take that with the pns manifold, then just weld it up though?

[d510addict]

Ya if I could even find the mani it would run me like 150 to get a drop pipe welded up and fitted to my current exhaust.

 

Or if I could find someone who can weld exhaust I coould try and grab the drop pipe with the mani and weld it to my current system but still idk. I think I am just gonna sell this z stuff and run the l20b its way more straight forward and there would be no compression ratio problems.

[HRH]

150 to weld a pipe? Who are you talking this stuff to? Should be a local exhaust shop that can do a little side work for a case of beer or at least only 60 bucks or something. If you want, I can look for a round port manifold at the local yard. Wouldn't cost much, I could bring it to Canby.

[hang_510]

does $150 include the fabbing of the 2-1 down pipe?

[Guest kamakazi620]

What about buying the u67 thats is unmilled at the wreackers I told you about?