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Do they fit the valve guides snug? What is the ID? Part number please?
I brought the valves, seals, seats, everything to my machine shop. He threw them together for me. Reputable shop, they know their stuff, and didn't have any trouble with anything fitting. Stock GM parts.
I can confirm the valve float at high RPM with stock Gen III springs. With a centrifugal blower, it is even more noticeable beause the higher the revs get, the more boost is produced, consequently, the more valve float you get.
Just to compare, the LS6 style is quite a steup up from the stock 3X00 spring...
Lets not forget what types of lifters we are using. Rollers are heavier. If I had the rollers and bigger cam, I'd want the LS2/6. For the hybrids, I don't see why one couldn't use the LS1 on the 272 with 1.6 rockers. Oh, and great find on the retainers and springs!!
Lets not forget what types of lifters we are using. Rollers are heavier. If I had the rollers and bigger cam, I'd want the LS2/6. For the hybrids, I don't see why one couldn't use the LS1 on the 272 with 1.6 rockers.
I have LS6 springs, SI valves, stock retainers and keeps, and viton seals. Just lookin for something to serve as a good seat. Was eyeing the Crane valve cups for the LS1 (144460-16) which Pace sells them for $~28, but I will need to open the ID up from .505 to .550.
Stock LA1 springs are 75lb @ 1.701" and 230lb @ 1.260". Thats .441" of measured compression, and the LA1 has .436" of valve lift. Stock LS1 springs are 76lb @ 1.8" and 220lb @ 1.32". Thats .480" of measured compression, and the LS1 has .472/.479" of valve lift. So basically an LS1 spring at an LA1 installed height and lift would have slightly higher closed pressure and about the same open pressure. Not a whole lot of difference though. I have a set of LS1 springs left over if you want 'em.
Thats interesting info on the retainers. I assume they made them so they also sit on the valve at the same height so they don't interfer with the rocker? Using those would lower your spring pressure a tiny bit too (if thats what you wanted). I don't see much use for them though since we've pretty much determined the LS6 springs will let us run plenty of lift still even at our lower height.
How about stock cam with forced induction? 5200RPM @ 11 PSI did a pretty good job at practically pushing my valves open with the stock springs. The valve float was very noticable. What keeps do ya use with those retainers? Finally, what seats are you looking at? ID locaters, or OD cups?
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