200 to 250 head swap.....pushrod length?

[tom_66]

I have a 250 cylinder (currently being rebuilt at the machine shop) that will be installed on my 200 block. I'll be re-using the non-adjustable rocker assembly from the 200 head. I believe the 250 head will be milled 0.060" to reduce the combustion chamber volume (plus 0.019" for the head gasket). How do I deal with the stock pushrod length. I read on an old post that the hydraulic lifters will compensate for .079", but I'm not sure on that. I also read that I can shim the rocker tower to compensate the difference, but wouldn't that affect the rocker geometry?



Tom

 

[66WarPony]

Hey Tom, you're looking for pushrods that are .0625" shorter than stock; I believe that those are Ford FE pushrods, but you can confirm that with Gary from Rocker Arms Unlimited (Redding, CA). You can contact him at (530)242-1316, he was the guy that was building the rockers for CI. If I remember correctly, the hydraulic lifters have 2.5mm of adjustment in them, but I'm not 100% on that; Gary on the other hand, can field any question you have. I was using .060 shim washers for the rocker pedestals when using the non-adjustable assembly, but an adjustable setup (I have the stock adjustables off of a 250) is ideal.

 

[tom_66]

66WarPony,

Thanks for the info.
I will contact RAU on Monday. Hopefully I can get a set of shorter pushrods. In the meantime, I'll be searching for a set of adjustable rockers.


Tom

 

[CZLN6]

Howdy Tom:

here's a thought, try the stock length push rods and turn the engine over slowly an see what happens. My guess is that it will be just fine.

Adios, David