Quote:

I talked to Jim with Indy while I was at the Mopar Nats. Pointed out to him what the Hughes site was saying about the spring seat and that limiting HP. His response was that the seat could be cut .100 with no problems. 1.625 installed height plus the .100 cut is equal to .1725. Add + .50 retainers and you are at 1.775. Put a + .50 keeper in and you are now at 1.825 Installed height. Are my figures correct? These installed heights should produce the HP plus some that Indy says the heads will make. I know this is my first post on this site so that will make some people suspect my info. I would recommend you call Indy and verify this info with Jim. I have a circle track IMCA modified customer in N.C. whose cylinder head guy is very impressed with these heads. The heads were on display at the Nats and they look pretty good. When this info was posted on Hughes website it caused me to lose the sale of 4 sets my customers had on order. I am trying to dispel bad information here. A person could cut the stock valves to match the RHS/Indy seats put the heads together and everything is a go. ALMOST a true bolt on. I recently had a STOCK set of magnums worked for the class I race, for $600+ more I could have had heads that out of the box would make a bunch more HP. Before anyone starts dishing me call Indy and speak to Jim.
Thanx
Allen



only caveat I can put on this info, if you're using 8mm magnum valves, is the keeper groove is very high up in the stem, and the stock keepers have the rib at the top. I was playing with different spring combos on a stock head, including checking out keepers from a GM 3100 V6 (same part as LSx motors), which have the groove in the middle of the rib, and added about .050-.060" IH to my stock mags. those keepers leave the top of the keeper flush with the top of the valve, though, and with the retainers I played with (GM3100, again same part as LSx motors) and stock magnum, the rocker hit the retainer before the valve tip. now both these retainers have a bit of a dish to them, so you might be able to get away with .050" retainers, but I doubt you can gain +.1" of IH from retainer/keeper tricks with stock magnum valves, especially since choices are quite limited for retaners and keepers for the 8mm stems (but it is getting better with the popularity of the LSx and 3G Hemi motors). now hone the guides to 11/32 and switch over to some .1" longer chev valves, that might give you a lot more options without horrendously affecting valvetrain geometry.

Last edited by patrick; 08/12/09 09:16 AM.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)