what is the maximum amount (0.xxx) you can machine the valve spring seats down? i am having headwork done and the machinist is telling me that my exhaust install height is short by .070. is this a machinable amount without sacrificing integral strength?
si valves 1.44/1.70, 340 springs isky chromemoly retainers. i believe he is shooting for a 1.67 install height. i thought these things would be a straight swap out on the ol /6 but uh....well....

The material is VERY THIN under the spring seats on a slant 6. I don't have a spec for you, but a long time ago I cut up a bad head to show the machinist how bad he had screwed up by machining .100" off all of my spring seats on a head I had done. The real sad part is, he ended up shimming them all back to get the right seat pressure. These guys are used to small block shivvys that lend themselves to massive amounts of meat removal under the spring. You may be OK with .070", but if it were me, I'd have them sink the valve seat a bit if they are real high or run different retainers depending on the cam and springs you are running.

Doug Dutra is the right person here to give you some definitive measurements and specs.

D/W

_________________

If it ain't broke, fix it!

yeah, i have been looking for offset retainers but am not having very much luck...the only ones i can find are all 10 degree, all the 10 degree keepers are single groove.....round and round. help.

Then just install as-is and check for coil bind. What is the valve lift spec on the cam?

D/W

_________________

If it ain't broke, fix it!

.448 valve lift on the cam

Comp makes some 10 degree, 2 and 4 groove keepers. p/n should be 740-12. (Or atleast that's the p/n PAW uses)

CStryker - hey man, thanks for the bit bout the keepers, found them at jegs....i thought i had looked thru them all but then again my lack of sufficient sleep might have something to do with that.....and may explain them damn purple elephants that keep following me.
thanks again.

I am also interested in how thick the spring floor is. My machinist and I have cut up an old head for putting hardened seats in that were over 1.5 in. and found it couldn't be done. I am working on running chivvy valves now with LS-1 beehive springs set at 1.8 in. installed higth. He thinks he has a way to do it by trimming the spring seat and using offset retainers. I will make sure he measures the thickness of the floor and post our findings. I hope this is still relevant.