iron head pistons in a 3400 w/cam

[Joseph Upson]

I was dealing with this issue on a reground stock cam regarding whether or not I would have to replace the pushrods since the base circle was reduced and the rocker arms non adjustable. Schneider Racing said that I shouldn't have a problem eventhough .040 was machined off the base circle. I have installed the cam and one pair of pushrods and I do have some preload on the lifter, but since that was with the engine upside down on the stand due to buttoning up the bottom end at the time, I haven't really checked to see how much preload. I believe at least .020 is required. I would still prefer to have the original specs in place. They also said that I would not loose any power from the reduced preload.

[SappySE107]

There is almost .090 off the MMS stage 2 cam.

[Superdave]

There is almost .090 off the MMS stage 2 cam.

wtf? that's alot of preload lost if the stock pushrods are used... I wonder why nobody's ever said anything before???

[torq455]

note to self: don't buy from ARI.

[SappySE107]

Turns out its .070 but this is a stage 1 cam in a stage 2 box. Looks like cammotion has scrwed up again. Stock base lobe is 1.290" and the stage 1 cam I have is 1.221"

[Superdave]

Turns out its .070 but this is a stage 1 cam in a stage 2 box. Looks like cammotion has scrwed up again. Stock base lobe is 1.290" and the stage 1 cam I have is 1.221"

that still dosen't seem right.. maybe for a regrind but for an aftermarket cam the base circle should still be the same. I've never had to use special pushrods in any engine i've built (most were SBC's)

I've had cams that were so big that you had to flop them side to side forever to get them to slide in...


that sucks about the cam tho, i bet you could sell it easy

[Joseph Upson]

that still dosen't seem right.. maybe for a regrind but for an aftermarket cam the base circle should still be the same. I've never had to use special pushrods in any engine i've built (most were SBC's)

I've had cams that were so big that you had to flop them side to side forever to get them to slide in...


that sucks about the cam tho, i bet you could sell it easy

Small block chevys and other engines with adjustable rocker arms don't count, it's the non adjustable rocker on the aluminum heads that's causing the fuss, so if the base circle on the replacement cam is less than stock you have to be mindful of the preload.

[moonwell]

Turns out its .070 but this is a stage 1 cam in a stage 2 box.

Haha, that was probably my stage 1, since I got the stage 2 in a stage 1 box

It doesn't make sense that Milzy would sell a cam that requires custom pushrods but not have any mention of that or have pushrods available...

[jackal2000]

oh he offers pushrods but they are stock length.