I'm getting ready to start building a back up motor which will ultimately be my main turbo motor. And I'm going to build and port and polish and install larger valves on a spare head. The head I have now is hoged out good with a set of ss 1.70 intake and 1.44 exhaust valves and im curious to see what is the largest size valve combination I can put on a long rod motor bored..80 to.100 over
This is a low compression motor that won't have any mill work done to the surface expect being cleaned up.
Any and all comments are welcome and appreciated
Aaron

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http://youtu.be/2Y4i4UOLiSA

http://www.forabodiesonly.com/mopar/sho ... p?t=126611

For that bore, you probably do not want to go above 1.76/1.50 - valve shrouding. Some folks have gone a bit above 1.80/1.50, though. For economy and availability, 1.72/1.50 SB Chev valves or 1.78/1.46 SB Ford valves are good choices.

Lou

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Home of Slant6-powered fun machines since 1988

I was looking at some Mopar valves from a set of #302 SB head.

Stainless in a turbo motor would be nice!

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

Man after looking at the combustion chamber I can't imagine you get much additional breathing out of larger valves, there's so much shrouding. I would like to see flow numbers of a head bolted down with larger valves.

Just realized Lou said the same thing, and if he says it I am sure it is true!

Has anyone tried offsetting the intake guide inward to squeeze in a larger valve with a stock-ish exhaust? Something like 1.80 with a 1.45 exhaust valve?

Then use a non-dual-pattern cam, instead of the commonly used longer-duration intake.

I believe the absolute largest valves you can put in a slant head without modifying the combustion chamber are Ford 300 valves.

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Casually looking for a Clifford hyperpak intake for cheap.

A few people have moved the intake valve over, and flow does improve. I have been meaning to try this. IIRC, Cameron Tilley had a head that was 1.84/1.40 or something in that neighborhood that flowed ~ 230 CFM intake. That motor made 350 HP @ crank on race gas, 12:1 NA motor.

Lou

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Home of Slant6-powered fun machines since 1988

To unshroud the intake you relieve the chamber next to it. Pictures of that have been posted here before.

I have seen claims that people have put 1.88 intakes in, and they make tremendous flow numbers on a bench, but I have never seen one of those motors ever run worth a crap.

The LS-1 uses a 2.02 intake and a 1.50 exhaust. I have been thinking of following that ratio on the next head Mike does for me.

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Official Cookie and Mater Tormentor.

Has anyone tried some 7mm valve stems also I'd kind of like to go with a 1.55 or 1.6 on the exhaust side it seems to me that's were a turbo motor would benefit from please correct me if I'm wrong.

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http://youtu.be/2Y4i4UOLiSA

http://www.forabodiesonly.com/mopar/sho ... p?t=126611

I'm also interested in moving the intake side does anyone have a link? This is the first I heard of this
Aaron

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http://youtu.be/2Y4i4UOLiSA

http://www.forabodiesonly.com/mopar/sho ... p?t=126611

For my last build I went with the SB Ford valves - you get 11/32" stems.

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63 Valiant Wagon
225 - 4 bbl

Like Lou said, 1.80 1.50 11/32. Easy to get.
Will

So I've been looking at some different valves what's a standard I/E measure from end to end? Also I started to work on the head if anyone is interested ill get some pics up
Aaron

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http://youtu.be/2Y4i4UOLiSA

http://www.forabodiesonly.com/mopar/sho ... p?t=126611

OK so I believe I've decided to try and run some 7mm titanium valves, there's a shop here locally that will cut some down to my desired size. Which means I'm going to have to change out my guides what's recommend stainless or bronze? Also I read in a different post that there is a certain thickness of hardened valve seat that's needed when installing larger valves?
I'm almost done with my port work but I want to get thehead into the machine shop and have the guides installed and the seats cut before I finish the port work. One last question when getting a head flow tested do you do that before final assembly?
Thanks all
Aaron

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http://youtu.be/2Y4i4UOLiSA

http://www.forabodiesonly.com/mopar/sho ... p?t=126611