My buddy is slowly modifying his 1966 Mustang with a 289..He has a set of hand me down 289 small port heads on it now. He started ordering parts for it and ordered a set of roller rockers.. Well he didn't put much thought into it and thought it was a direct swap from rail type rockers to a roller rocker.. Now he has found out that he has to replace his pressed in studs with screw in type studs and add guide plates..

Question #1 - I have heard that you must mill down the surface of the head .23" to compensate for the added thickness of the guide plate and nuts.. Is this mandatory??

Question #2 - ( If they don't have to be removed for Question #1 ^^) Can you drill and tap the heads to accept screw in studs while the heads are on the car?

I was trying to talk him into pulling the heads to have them tapped accurately, but he won't listen to me.. But if they have to be milled down, that will be the deciding factor in their removal..

Thanks, Richard

 

you must have the heads milled and tapped for new style studs and guideplates. im just got mine done.

 

The heads are not worth the machine work. If it had rail rockers it wasn't 289 heads. Those head had cast in pushrod guides through the heads

 

only 1965, mine are 1966 and there are no internal guideplates.

if you do get machine work, port the hell out of them including bowl work. they make some decently good power with the right cam, intake combo.

 

I stand corrected. Ford stopped the slotted pushrod holes in 65. I was thinking in the back of my mind it was 68. Thanks for clearing that up. Hard to remember everything. I can't remember the last set of those heads I had in my hands.

 

*Answered my question while i was typing this one*

Just to make sure i am thinking right... Rail rockers have kind of a box that holds them on top of the valve.. Correct?

You say that 289 heads don't have rail type rockers?? These are supposed to be the 289 small port but i haven't ever checked.. (cause it ain't my car)

So based on the fact that they have the rail type rockers, you think they are a casting that is not worth putting alot of money into??

Thanks, Richard

 

The early 64-65 289's had slotted heads but 66- had a boxed in slotted rocker. In that respect I was wrong. I don't think any of those old castings are worth much unless they are for restoration.

 

i dunno man my buddy has a well worked set of '65 289's on his fairlane (ratrap) and thats pretty beefy 302. full cage and everything.

i talked to a engine builder or two and thet all said if they can be done for under 500 they are well worth the money for a budget head. well with everything i purchased and paid for machine work well landed me just a tad over 500. and that extra bump in compression, really nice comp cam, in conjunction with nitrous...i think it'll be a pretty quick car.

and that price includes stuff i would have had to buy anyways with any head because of the cam requirements. the only thing i really bought for the heads were larger valves and screw in studs, everything else is machine work.

 

what are the casting numbers on the heads???

 

I'd go with some later heads that have the hardened seats too, don't forget that $400 upgrade!!