Do I need longer push rods?

[low91]

Stock base circle measured in at 1.55 and the new cam was 1.49. Will I need longer rods or will stock length be fine?

[low91]

So nobody on this site has done a cam swap huh?

[Atomic]

so base radius is (1.55-1.49)/2 = 0.03" smaller

pre-load on the lifters is in the 0.05-0.07 range so its going to be close.

I would get some 7.425" hardened pushrods, but the best way is to actually measure what you need. an adjustable pushrod is <$20

[Madd Maxx]

Factory lifter preload on the LS engines that I've measured has been in the 0.115-0.125" range. Your new cam will give you a preload of about 0.090". I would consider that to be a good value for a street engine. You probably won't even notice any increase in lifter noise level. Stay with your stock pushrod length.

[farmtruc]

I've done the swap several times and didn't change pushrod size.

Like it was said above, the only way to get the exact measurement is to measure it.

[low91]

I'm hoping my stock rods will work but wouldn't that give me less lift which is one point of swapping cams in the first place? I'm ordering a pushrod checker tonight, how hard are they to use? and also if my stock rods are long enough would it be alright to use them or will I need hardend rods even with such a small cam(212/218 .557/.562) ?

[Atomic]

turn it until there is no lash in the rocker then calculate the length of the rod, then add the lifter preload you want then thats your length....very easy to use. i would get hardened ones regardless, cheap insurance.

[low91]

turn it until there is no lash in the rocker then calculate the length of the rod, then add the lifter preload you want then thats your length....very easy to use. i would get hardened ones regardless, cheap insurance.

Thanks. How do I figure out the lifter preload?

[Atomic]

I always see factory lifter ideal preload in the 0.050 to 0.075 inch range