Exhaust guides and seats

Discussion of the Marine / Industrial Hemis.

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firepower354
Posts: 58
Joined: Mon Mar 29, 2004 11:26 pm
Location: MI

Exhaust guides and seats

Postby firepower354 » Tue Apr 05, 2005 10:34 pm

I have a set of truck heads I'm planning to set up for my rod build. I don't think they've ever been apart. Anyone have info on replacing truck exhaust guides with car versions? Same OD? They are for a 7/16 stem valve! Also the seat inserts look to be around 1/2" deep! Normal rebuild unleaded update stuff is in the .200-.250 range. The short turn of the exhaust ports seems to have extra material that should hurt flow. How far is the water away? I like that there's no exhaust crossover in the heads but know this limits intake choices. Thanks!
Crank up the boost till you run over the crank!

41hemi
Posts: 78
Joined: Thu Jul 17, 2003 7:35 pm
Location: Elkridge, Maryland

heads

Postby 41hemi » Wed Apr 06, 2005 6:09 pm

Sounds like you probably have the sodium filled stems that some truck and marine engines had. The o.d. of truck and car guides should be the same. I know that a marine 354 engine and a 392 that I have will interchange. Can't help with how much meat can come out of the ports.
41 Chevy with blown 330 Desoto / 32 Ford coupe with blown 392 Chrysler

budmspeeco
Posts: 133
Joined: Tue Dec 21, 2004 5:35 pm
Location: South Houston, Texas

exhaust guides and seats

Postby budmspeeco » Wed Apr 06, 2005 10:22 pm

I do cylinder head work. I have a couple of sets of the heads you have. I plan on cutting the guides flush with the heads on the spring side and cut the port side back about half of what is sticking out. I am going to bore the existing guides to 1/2 inch and install bronze guides, not guide liners, the approiate length to leave about .750 ( or what length it takes to clear the retainers at full lift) above the spring seat base and cut it flush with the other end. Stem seals push right on. You can get the guides in 5/16, 11/32, or 3/8 stem size. I do not understand why more hemi rebuilders don't use thes method. I have done B.Bl. chevy heads like that for years because the seats do not align with the valve seat centers most of the time if the guides are pushed out and new ones installed . If you plan to use larger valves it is not a problem though. Ask your machinist about this. The guides coming out should not be a problem since these guides are notorious for being some of the hardest to remove.
'48 anglia

firepower354
Posts: 58
Joined: Mon Mar 29, 2004 11:26 pm
Location: MI

Postby firepower354 » Thu Apr 07, 2005 6:31 am

Thanks 41, they do feel a bit light to be solid stems. I wonder if the big stems would be strong enough for a 5500rpm street engine? The port gets huge right after the seats so it shouldn't reduce flow like it would on the intake side.

Bud, I was worried about making the guides too thin and forcing them partway out. Let me know how yours works. What are you using for a press fit? I did a R&R set back when I was at Batten, a now-closed race shop near Detroit. I built a driver on the lathe and spent about 8 hours with a 3 pound sledge, so maybe they are in there good. I suppose that at less than 1/2 the price of HH solid ones, it might be the way to go.

Thanks
Crank up the boost till you run over the crank!


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