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I guess my next questions is in regards to pushrods and rocker arms. I've been browsing around on some dakota forums and they're claiming new pushrods are an absolute necessity with a new cam. True?



first off, to answer scratchin's question, NO. the LS1 springs and GM3100 springs have the same top end geometry and use the same PN for a spring retainer. they are both beehives, with ~.9" OD on the top. but the LS1 is a 1.2" OD bottom with a blueprint 1.8" IH from the factory, the 3100 springs are a 1.4" OD bottom (so they fit the magnum heads), with a a blueprint IH of ~1.7", and a coil bind height of ~1.065".

the 2.2L retainers allow the use of any straight 1.35-1.45" OD spring with an ID greater than ~ .9" with the factory 8mm stems and keepers....they fit my hughes 1110 springs great.

to answer the pushrod question, "it depends". on my build, stock magnum PR's worked fine, this with a factory '86 block deck height (no idea how close it was to blueprint), thin Mr. gasket head gasket (.028" compressed), my roller cam reground, and when I had the heads done, I had the valves sunk .030" to gain a little more IH. with the 2.2L retainers and magnum keepers, my installed height was 1.60" with the factory valve job. coil bind is 1.040", so I had .560" travel before coil bind, but .540" before the keepers hit the old valve seals on the heads. my current IH is 1.63" and I now have .590" travel before coil bind, and ~.560-.570" travel before the keepers hit the seals, so I should be good if I ever want to crank the lift up into the .530-.540" range, as long as I have V/P clearance...with the stock pistons in the hole .055", my measured V/P clearance was ~ 1/8", but that's as much a function of cam duration as cam lift.

I found some comp pushrods for a ford 302 that were ~ .020" longer than the mag PR's, that when I tried them out assembling the engine, worked fine, too.

Last edited by patrick; 01/29/10 09:33 AM.
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