Just wondering if there was anyway to tell what rocker arms are on my heads? Ive got a GM350HO and they came with 1.5 rockers but oddly enough Ive heard that some of these crate engines came with 1.6 rockers but were still listed as 1.5s. Is there something stamped on the rocker or anything like that that I can tell what Ive actually got?

 

Well, if you could very accurately measure the rockers (measure the distance from the center of the rod pocket to the center of the main rocker pivot, then measure the center of the rocker pivot to the spot where the rocker touches the valve stem) and divide the larger number by the smaller number, you will get either 1.5 or 1.6....

 

Well considering that GM has NEVER installed 1.6 rockers on ANY OTHER small block, I'd say it's not likely that they did so on yours.

So whoever you "heard" that from, I'd take that person's pronouncements a little less seriously in the future.

 

LT4's came stock from the factory with 1.6 full rollers. Otherwise I agree with you.

 

Put a dial indicator (in the depressed position) on the valve spring retainer when the valve is fully closed, zero the indicator dial. Turn the engine over until the valve is fully open, record the dial indicator reading.

Now put the dial indicator on the pushrod side of the same rocker, repeat (the indicator will travel in the opposite direction, of course).

Divide the first result by the 2nd. You'll have your rocker arm ratio.

(You could do the same thing with a depth gage or caliper, as long as you referenced the same point on the head for the open & closed positions.)

 

GM didn't make a stamped steel 1.6 rocker. So if they're steel, they're 1.5. They did, as posted, install 1.6's on the lt4 but all of the 1.6's I've seen (gm or aftermarket) have 1.6 stamped on them.

 

Agreed... if they are stamped, they are 1.5s. The only 1.6's GM used were on the LT4, and they were aluminum full rollers made by Crane for GM.