Setting Chrome Moly Pushrods

[cgarr]

I have a set of Norris Chorme Moly Pushrods (4130)? in my engine and just for the fun of it I checked the valves when hot, they were about 8+ and 10+ I set them cold 5 and 7 do these pushrods not expand at the same rate? should the cold setting be different? They are not any too noisy., just leave them alone?

Thanks

Craig

[adot]

Hey Craig

I think the valves expanded, not the pushrods ?

Brett

[Griznant]

Most chromoly pushrods need to be set at 0 lash when cold. They will not expand at the same rate as aluminum ones, and therefore as the engine expands, the valve lash will open up.

This may be different for the 912 version, but I assume not. My experience is limited to VW chromoly pushrods (of which I just installed a new set in my T4 with ceramic lifters). I set mine when the pushrod just starts to turn against the rocker.

Later,

G

[Jake Raby]

I use zero lash on my custom Manton pushrods for every engine I build.

[pokemon]

Same experience on my 912 with cast iron cylinders. I replaced the push-rods with new ones as delivered by Porsche. They fit all 356-912 engines as the shop guy told me. He was right they fit but he forgot to say they expand differently from the other types.
Don't know if they are chromemoly. They are non-magnetic so no steel or iron in them. Thought they were stainless-steel.
The valve play increased when hot.
The main thing to remember. Set the valves cold and have them checked once when hot to make sure there is still some play when hot.

Regards,
Patrick

[Jake Raby]

setting at zero with a chromoly P rod yields me about .008 when running at 350F head temp....