Rocker and pushrods

Matthew68

Well-known member
Hi Folks,

Hoping for some math wizards to chime in. I have a OZ250-2V head that was milled .050”. I’m using the Victor head gasket (.044” crush per the handbook). My block is unmolested, no decking or anything.

I have a set of non-adjustable rocker assembly with the stock pushrods (8.230”). Will these work, even with the head cut?

While I have two sets of adjustable rockers, I didn’t know if it’s necessary to go out and spend the money on the adjustable if it’s not needed. Note: eventually I’m switching out to Yella Terra full rollers (already on my shelf) but that will come with the bottom end rebuild in the future. That’s my avoidance with wanting to spend the extra $$ on the cup-ball pushrods for the adjustable rockers.

Here’s my math, with the understanding that the hydraulic lifters can absorb 0.125” difference:

.050” Head mill
.044” Victor gasket thickness
.025” old FoMoCo gasket

.044”-.025” = .019” gasket increase

.050”- .019” = .031” lowering, well within the .125” lifter accommodation.

Did I do this correctly?

Cheers,
Matthew
 
Yes it looks correct, I'd only use that .050 as -.050 because the head is milled, so you can't get it wrong with some longer calculations. Or at least I calculated like this:

There is the block. If using old Ford gasket the height is 0. If you want to get it back there with .019 in thicker gasket you mill your head .019 in. When you have your head milled .050 in, its .019 - .050 and you get -.031 in.

Theoretically you could mill your head .125 + .019 = 0.144 in, and still use the same lifters, but there is no need for that.
 
Ok, thanks.

My other option is a have a set of adjustable rocker arms. VI only has the 8.230” pushrods in stock. If I purchased these, do the adjustable rockers account for the head milling? How much adjustment do they have for the 8.230” pushrods +/-?

Cheers,
Matthew
 
The yella-terra rockers are out of the question till you install V-8 oil through lifters which are also .150" higher, thus you also need shorter pushrods.
Also have to block the oil passage at the LR of the block. The reason why the headgasket will not hold line oil pressure.
Install the adajustable rockers & see of the contact pattern on the valve stem sweep is closest to the center of the valve. If so you are ok.
If not get an adjustable pushrod from one of the cam mfg's to get the correct length.
 
wsa111":maqstb0k said:
The yella-terra rockers are out of the question till you install V-8 oil through lifters which are also .150" higher, thus you also need shorter pushrods.
Also have to block the oil passage at the LR of the block. The reason why the headgasket will not hold line oil pressure.
Install the adajustable rockers & see of the contact pattern on the valve stem sweep is closest to the center of the valve. If so you are ok.
If not get an adjustable pushrod from one of the cam mfg's to get the correct length.

Thanks Bill. I’m not installing the YT until I rebuild the block and can do a new cam. I’ll keep that in mind though. I have a pushrod checker for the nonadjustable coming in a few days.

Guess I need to order pushrods for the adjustables. Any idea how much adjustment +/- the adjustables can account for?
 
Depends if the adjuster is centered at zero lash, you only want to depress the lifter cup as little as possible. 1/8-1/4 of a turn should be optimum.
 
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