Okay engine experts, my '66 289 heads are at the machine shop this very moment being rebuilt. I am installing them on my 302. Do I need different pushrods with these heads, or can I use the '73-'75 pushrods with them? They are for use with the rail-type rockers, and I'm using Comp Cams roller-tip rockers...:confused:
They will be fine. 289 used a 6.800 long pushrod as did the 68-69 302. In 69 they changed the 302 to a 6.900 pushrod. That 100 thousandths will not change the rocker angle enough to cause the rails to bind or hit the springs. Especially with the Comp Cams roller rail type rockers. They work quite well! Eric
Guideplates? IF you are installing guideplates, you will need ChromeMoly pushrods. Those guideplates will eat them up in no time. I would ask the machinist to make sure that the bosses have not been ground down if screw in studs were installed now or anytime in the past. Some machinist do that when installing studs to affect geometry. Good luck. Seth
Thanks. I'm not using guide plates or screw-in studs. Cam is only .456 lift. It's a '68 302 with '66 289 heads......
Exactly .... no guide plate should be used with the rail type roller rockers. I've put these into several motors and really like them.
The '66 289 heads I used to run had slots in them to guide the pushrods, not just round holes. If the heads have fitted slots you should NOT use guide plates OR rail-type rocker arms, binding can occur.
You had a K-code head. Unique head with cast in push rod guides (the slots) and cast in spring locating cups. Also had screw in studs and a smaller combustion chamber. Great head in its day!
I have had a few sets like that...think I still have a set if they're still any good. Kinda got flooded along with everything else around here. I need to check that stuff out.
So if they have the slots (need to look at them again), do I need to use hardened pushrods like those that are used with guide plates??...
Here's another question: is there a 1.84/1.54 size valve with the proper length stem that will work with these heads? The 351W valves are like .200" longer...
The 351W valves will work. You would probably need 351W springs also for their higher installed height(1.8 vs 1.7, I think). I have used 351W valves in a 302 head with the 6.9 pushrods and had no problems. The '66 heads should have adjustable studs. Where you might have a problem is if the heads used a positive stop shouldered stud and you couldn't adjust lifter preload(unless you used polylocks, which is what I did).
No , BTW, I also have had several of those heads that were not K code. Scrapped most of them cause the just won't flow with bigger cam etc.
T. L. if the pushrod is guiding the rocker either by a plate or a slot in the head, it must be hardened. otherwise you will end up with shavings from the pushrod in your oil.
