Cali Z

Okay, I have done some searching and haven't gotten a straight answer about this. I have found mixed answers as to whether or not I can run stock L98's with just upgraded springs and 1.5 rr, with the hotcam. I have hardened pushrods on it, and a set of Comp springs that were on a set of trickflow heads, but from what I am told they are too big for the spring pockets on the L98s. Also have a double roller timing chain.

This is on a 350 (89 Iroc) , stock compression, tpi setup. So as of now I have

- hardened pushrods
- double roller timing chain
- L98 heads, currently stock
- 1.5 rr
I have stiffer Comp springs but I was told they were too big for the L98 spring pockets. So my question is will it work with just stiffer springs and the other parts that I for it? I have searched alot but keep coming up with Yes and No answers. Thanks

Vader

With 1.5:1 rockers, the net valve lift for that cam would be in the area of 0.492". Many stock heads experience valve guide/retainer interference at as little as 0.480" lifts. Further, the stiffness (or starting pressure and rate) of the spring is less a factor in your case than the height at which the coils bind together, making it more of a solid cylinder than a spring. If the coils bind at something less than 0.492", you'll have a valve train crash. Usually, the push rods or rockers lose that battle, but you can also wipe out a cam lobe or break a lifter roller axle.

The proper setup would have springs adequate to handle both the lift range and acceleration rates of the cam lobes at the desired operation RPM. The heads would be machined not only to accept the springs within the spring pockets, but would also have the valve guides cut down to provide safe clearance for the seals and retainers. Given that the springs would likely have a higher seat pressure and rate, the rocker studs would also need to be either pinned in place, or better yet, removed completely so the heads could be tapped to accept screwed rocker studs that will not pull out under high spring pressures.

Other than that, it should work just fine.

Cali Z

Okay, I'll just use stock heads and cam. Thanks for the help.

Vader

Your other options are to machine the heads as described, or get a different cam with slightly less lobe.

Cali Z

Ya, I know, but with the budget I'm going with, I think it would be most affordable to just go with the stock heads/cam setup and install a set of 1.6rr. The aluminum full roller set looks pretty nice, and affordable too. This way, no machining will be necassary and I'll stay in budget.