Hey guys, I have a 66' 289 and I'm in the middle of swapping my heads with a set of D0OE-C 351W heads. I have read through a few articles explaining the swap and non of them mention any difference in rocker arm stud size. The studs on my 289 heads appear to be about 3/8" while the ones in my 351W heads are smaller, probably 5/16". Just wondering if any of you guys know if stud diameters changed between years or if the guys that rebuild the 351W heads screwed up and put the wrong studs in. Also the new studs have less threaded length than the 289 studs. After setting everything on the new heads it appears there may be excessinve play in the rockers. Is there any way to shim the rockers or should I just get a new set of studs? Thanks for the help.

Kevin

 

Sounds like you need to change the studs. Are they screw in? If they aren't, take the heads to a machine shop and have them set up to receive screw in studs and guideplates. That could be the difference as well...one set of heads may have already had that work done.

 

I found the correct 5/16" nuts for the studs on the 351W heads but there is still too much play even when I screw the nut all the way down. I was thinking of just using some 1/8" shims to go between the rocker arm ball and the nut. That would eliminate the play in the rockers. Any thoughts on this idea? Thanks.

Kevin

 

the studs prolly are 5/16. I have 351's on a 289 and tried to buy some roller rockers but the 3/8 wouldn't fit and the only other size was 7/16 which is bigger. Also buy the right size pushrod i heard you need the 6.905 instead of the 6.805 which is stock for the 289. I haven't measurd mine yet, but i think it's incorrect b/c there is some noise and i tried like 2 different ways of adjusting the valves and the noise is still there.

 

I finally got my new heads put on my car. I still need to finish porting the intake and figuring out the rocker arm situation but here are some pics of the new heads.


[IMG]local://upfiles/6701/DA5A5CC5C78446B283BC076C9FC6D374.jpg[/IMG]

[IMG]local://upfiles/6701/ED121921B9C642F3B384E39ABF87CDE2.jpg[/IMG]

 

Thems push in studs. They aren't going to stay put and your rockers will come loose over time...the more lift your cam has and the higher rpm you push it, the worse the problem will be. That could also be part of your problem with the rockers.

It is worth the effort to get screw in studs installed.

 

You're going to have to take the heads back off. You need new studs and guideplates. ARP and others have them. I have a set of heads at a machine shop right now. They have to extract the press-in studs, machine down the little boss/pedestal to make room for the guide plate thickness to maintain a correct height for mounting the roller rocker. They then thread the holes. You can then put in the studs (through the guide plate and mount the roller rockers. If everything was done right the pushrods will be the right length. You need guide plates to keep the rocker arms from rotating on the stud.
I've heard that the 351 combustion chamber is also larger than the 289. If so you'll lose compressoin and power. I'll find out if this is true tomorrow. If you want to keep the compression up, the head will have to be milled. you can mill it up to .005-.010 without affecting the intake mounting. If it's milled more then the intake face of the head will have to be milled. A typical machin shop has the charts to figure out how much.
I'll be milling mine because I modified the combustion chamber shape to "unshroud" the intake valve and therefore the volume went up.
I've also heard taht there are more coolant holes in the 289 than the 351. You'll need to check this and drill holes in the 351. I've done this on 312 heads on a 292 block. Not a big deal.

Good luck