Head Swap

[dirtplay18]

Thinking of swapping heads on my 23* sbc. Both sets are the same except the ones I'm thinking of using are angle milled .250, what affect will this have on my rocker arm geometry? Meaning, will I be able to use the same length pushrods that are in it now?

[r3tracing]

Angled .250 wow are you sure it is that much.

[dirtplay18]

Yes it is that much. My machinist has advised me to try it for a while to boost my compression. More than enough valve to piston clearance to do it.

[kilroy be here]

Angled .250 wow are you sure it is that much.

holy crap!!!!! and I used to think .100 was a lot!!!! gotta be a biotch getting the intake to fit!!!

[dereksehi]

One thing that you might want to watch with the piston to valve clearance is when you angle mill the head that much you are going to change the angle of the valve head in relation to the piston. This could cause the piston to valve clearance to reduce even more do to the change of angle.

[runyou-2]

Sooooo,IF you can get the head bolts started,only one side of the bolt head holds the head in place?

[fastford]

I have cut heads .200 before, I used head studs and had to message the holes in the heads a little as well as reface the area where the washers meet the heads, I don't know if you have to do this, I just don't like a stud or bolt in a bind.

[dirtplay18]

I use head studs, the intake surface has been machined to compensate, also the bolt holes were machined to keep the washer & nut flat. Any thoughts on the rocker arm geometry???

[autoshop]

you'll proabaly have to run shorter pushrods

[FF21]

.250 is'nt to bad of an angle mill.I remember Bill Hendren talking about angle milling the heads on his steel head motors .375 it was a Dart head of course.I think he said it took like 40 hrs just for milling.

[Krooser]

The heads on our SBC are milled .160. We used custom length push rods, +.100 valves and stock rocker arms. Our geometry is near perfect. The .500 lift cam allows enough clearance for the valves vs. pistons.

Your mileage may vary.

[JHobbs26]

what FF21 said, 40hrs of machine work to get everything to bolt back up. Probably will need different length pushrods. If your class has a 23* head rule, and they have an accurate way of checking you probably will not pass. 10yrs ago it was roughly $1500 to have the heads milled .375"

[powerslide]

Mark the tip of the valve and roll the motor over a couple times, only way you will know for sure. I would be a little hesistant though if the machinist who is telling you to do this isn't for sure what you need.