Help! Swapped 302 heads on my 318.
I had the '452 heads for a 440 milled .050 to raise compression on the first 440 I rebuilt...way back in 2001. I used the stock pushrods and it ran great!
So you got lucky.
I had .010” cut on my 308’s and had to have the intake milled to line up the intake, that shouldn’t have been necessary. They were stock with no indications of previous milling. Same with my 340, no signs of previous decking and my piston heights were right on. Of course I don’t know for sure what was done to the block or the heads before I got them, which is part of my point too. With a set of 302’s from the junkyard like the OP has there’s no guarantee that they haven’t been cut before.
According to stock specs my 340 with hydraulic lifters and factory style adjustable rockers should have 7.25” long push rods. I measured and I use 7.1” pushrods. A .010” cut didn’t make that difference, my cam and lifters did.
The OP does not have a stock cam or lifters, he has a set of heads that he doesn’t know the history on, and quite frankly who knows if his valve height and geometry is stock. Maybe it is, maybe it isn’t. But he could very well be well out of spec using stock pushrods, even with hydraulic lifters.
At this point he has an issue, so he needs to check and measure all of this stuff.