I have searched all over about how to properly install rocker arms on my 55 pontiac 287. I have found multiple sugestions on how to do it. The most seem to say tighten the nuts to 15~20 foot lbs, but some say thats not the way. Any help would be great.
I know that '55 rocker studs were 3/8, whereas '56-'60 studs were a puny 5/16. Check out your studs; if they have a "step" in them where the nut would bottom out when you torqued them dowm, then the 20 ft-lb method would be correct, but if they're straight, then they're adjustable loke a sbc and you need to set them somewhere between 1/2 and 1 1/2 turn past zero lash.
If you're using the stock rocker arms and nuts, tighten them to 20 ft pounds and your done. The stock nuts have tapered seats the bottom out on the shanks of the bottlenecked rocker arm studs.
I'll have to check to see if the studs are tapered or not. I tried the 20 foot lbs way and it seemed to not run good as when I adjusted them like I would a sbc. Will the lifters adjust to where I set them after a while of running? I didn't run it long at the 20 pound setting because of how poor it ran. I have also heard of people using chevy rockers on these motors. I have tried them they fit and seem to run. Any ideas on that?
i adjusted mine with engine running turn the nut then back it off a hair so the rocker is snug with a little play. worked out great.
What does a factory shop manual tell you? If I had one here I'd look it up, but '55 is a year I don't have handy. Motor's Auto Repair manual may be just as good.
The reason the 20 ft pound thing may not have worked for you is if your heads have been resurfaced or milled. That would change the valve stem to rocker arm clearance with stock pushrods. Here is a pretty detailed tutorial on the subject: http://www.pontiacstreetperformance.com/psp/rockers.html Don
I went through this last summer. If you don't torque the factory nuts down, they will loosen up. You have to get a locking nut, modify your factory nuts or find Poly-Locks to make them truly adjustable like a SBC. I ended up putting hardened washers on top of my rocker studs and then used an all metal lock nut. Took some fine tuning but it's correct now. Jim Butler performance has a detailed procedure for this on their web site. Call him if you really get stuck on it. He called me back personally and talked tuning and hot rods for over 20 minutes. Nice guy, very helpful and I've never spent a dime with him. PM me, if you're local I may be able to come help.
56-79 rocker nuts were torqued to 20 ft. lbs. 55 was the only year they were adjustable like a small block chev. 0 lash plus a half a turn is a good start to get it running, then adjust while running. I usually put mine at about a half a turn after they stop clicking. Good Luck, Bud
Just as a sidenote, I had a 63 Pontiac 389 that I put a 421 cam in. One rocker arm stud would occasionally pull up when I got on it hard. I carried a big hammer in the trunk and would tap it back down and be back on the road again. I eventually put a new stud in it with locktite and it never came up again. Don
Thanks for the help guys. The rocker shafts are not tapered, so i installed them just how I would a sbc. Seem to be working good so far. but still a little more noisy than I would like.
Adjusting them "Chevy way" is better than the stock seated nut style. The "Chevy way" enables you to set them each at the same level of lifter piston travel. On my OT 68 GTO, I installed poly-locks and set them Chevy way. The engine seems to run smoother. I can also set them looser at 1/2 turn for less pump-up problems, whereas the stock bottom out approach was set way tighter.
Any one ever used Small block Chevy rockers on this era pontiac? I have multiple worn rockers and heard chevy ones have been used before? Any tips on this Thanks
No good unless you plan on altering your oiling system---all '55-'62 Pontiacs oiled the rocker arms through hollow rocker studs with a small oiling hole in them.
The chevy rockers look very close but the pontiac rockers are a little longer. The 287 did have hollow rocker pivot balls and stud oiling, but it also had hollow pushrods so if you got the correct size and ratio rockers that have holes in the pushrods cup(is that the correct terminology?) it will still oil. Actually it will oil a lot more.
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