need advice: vortec heads, pushrods, rockers

[instantkevin]

okay... u may be familiar with my setup: carbed 350, vortec heads, blah blah (look at my signature).

when going with a bigger cam, it is necessary to drill the pushrod holes out so that the pushrods don't get bent. i had the machine shop do it before i put the engine togther but they still weren't wide enough, so now I'm doing it again with a 31/64 drill bit. but after i start the engine, the pushrods will go back to touching/rubbing against the pushrod hole (which is what causes the bending). I looked down in there and i can see that the lifter is not always perfectly lined up (vertically) with the valve stud, and so the pushrod has to be slightly angled to sit into the rocker and the lifter at the same time (which causes it to rub the hole).

I'm wondering if this is normal. and apparently there is no harm in making the pushrod hole "too big." but now I'm second guessing myself and thinking that it may be possible that heads are on the wrong side of the engine. but with L31 vortec heads, there is not distinction between left and right head, right?? A stupid question, I know.... but I just want to cover all the bases.

My plan, at the momment is to drill them out wider, where they rub. Anybody got any other ideas or recommendations?

And before anybody mentions it.... i am keeping the metal shavings out of the engine. I got creative and I'm using a system of rags, a flexible handle, and 2 magnets to keep shavings out of the lifter valley, and then cleaning it up with another magnet. Plus I have two powerful magnets stuck to the bottom of the oil pan, just for insurance.

[balls_to_the_wall]

Why don't you just pull the pushrods out and drill them?

[89IROC&RS]

how big is your cam?????

you may need a set of custom length pushrods, they are rather common, and you can order them off the shelf. what you should do is order an adjustable pushrod, and adjust it until you dont have the rubbing anymore. then measure that pushrod and order a set of the same length.

[89IROC&RS]

it looks like they are rubbing on the intake side, so id say you want some that are a bit shorter than stock.

[instantkevin]

Interesting. It's a comp cam's 268 (on the sig). I'm not at the garage right now but I'll have to go back and check, but I don't think they were rubbing on the top or bottom of the pushrod hole. pretty sure they were rubbing on the side of the hole. Different length pushrods won't help that will it?

I guess I didn't make myself clear. I have already drilled the holes (a second time) with a larger drill bit and they still rub on some of them.

[89IROC&RS]

are those stamped steel rocker arms the ones you are using with the cam??? if so, i dont think those are self aligning (i could be wrong) and if they are not, you need to put some guideplates on there. that may be your problem. or upgrade to a set of self aligning roller rocker arms.

[instantkevin]

well.... i found my mistake. you found it too IROC. my engine came out of a 79 truck and I'm re-using those rockers. they didn't start using self-aligning rockers till 87.

I thought they were fine... long time ago I saw a pict of self-aligning rockers and they looked pretty close to the ones I have... so I thought they were right. I just overlooked the groove in them.

They do make stamped steel self-aligning rockers, though. I'll be getting some of those next week... then finally I'll be driving. Thanks IROC.

[89IROC&RS]

SCORE!!! man that felt good, its been forever since i figured out something like that

[instantkevin]

yea... good one. especially considering that I didn't even mention that the rockers kept sliding off of the valve stem (after then engine was started). Nice.

[89IROC&RS]

hahaha, yeah that could have been a giveaway