Hi, I been posting on my 85 rebuild for a while. I am reassembling my engine now and realize I need a different length pushrod. I am installing Crane 1.6 roller rockers and everything seems to fit great. No bind or clearance issues. This is my first engine build.

I set the lash according to the instructions and did the magic marker valve stem check and the stock pushrod wear mark is 40-30% towards the exhaust side. I have an adjustable pushrod, and going 1/8 inch shorter seems to put the wear mark very close to the center of the valve stem at all four corners of my engine.

I have been ordering parts from summit and the only thing I see on their site is a $100 comp cams multipiece set where I build a custom length pushrod. Do I have any other options with 5/16 pushrods? Don't need a hardened pushrod.

EDIT - (I was looking in the wrong section at summit they do have a number of different sizes, just need to figure out which one I need)

I have been turning the crank by hand, should I see oil pumping up through the lifters?

EDIT - (Don't have the optispark gear in so the cam isn't turning the oil pump, see I'm learning)

Also I don't understand how the hydraulic lifters affect the lash. Does my setting the lash compress the lifter? They can't be pumping up because there is no oil coming out the top, or are they already pumped up? I did not disassemble them.

 

(my 2-cents, FWIW) -- my somewhat limited knowledge on pushrod length tells me that you need to go even shorter. I seem to recall, you want the witness mark on the valve stem to be about 1/3rd toward the inboard side of the stem.

it sounds like you have an adjustable pushrod, so i'd determine the exact length needed and purchase an "off the shelf" set to the closest length as measured. unless you're building a full blown race engine, I wouldn't go too crazy with some custom, high-dollar pushrods.

on the lifters - once you find zero lash, any further adjustment will compress the plunger spring within the lifter. ideally, you want it be midway on that travel the plunger travel will differ between manufacturers, but for a standard OE SBC stuff I use .060" plunger travel. don't put too much into the "pumped-up/leak down" and adjustment lifter stuff. (per manufacturers specs or FSM), SET IT AND FORGET IT! good luck on your build!

 

Ill usually use a solid lifter for that or a checker spring instead (easier)
You wont see oil pumping up if turning it by hand.

 

I have been reading that you want the wear mark you get when you put the black marker on the valve stem to be perfectly centered. I'm talking about rotating the crank to create the mark. So that it is always pressing down as close to the exact center. I think what you are talking about is for when you just wiggle the rocker back and forth without turning the crank.

 

well, as I said, my experience is somewhat limited, and I wasn't talking about wiggling the rocker across the tip. from my understanding, the rocker arm movement is somewhat in an arc, and a roller tipped rocker will move slightly across the valve stem tip. if you start out at the mid-point, or the 50% mark, you'll end up about 3/4 across the stem. if you start out at about the 30% mark, as the rocker travels in this arc, it will end up near the 50% mark which is ultimately where you want to be. this again only applies to roller tipped rockers, and not conventional stamped steel rockers. again, as I said, i'm far from an expert -

 

Do your roller rockers have guides on the side to keep them on the valve stem? If not you will need hardened pushrods and pushrod guide plates.

 

Sure summit has something like this makes it easy so you dont have the issue with pushing the plunger down

https://www.amazon.com/Competition-C.../dp/B000CIO9W0

 

The wear mark I was creating seemed to only be 12.5% of the stem diameter or half a quarter of the total. You seemed to have seen a larger wear area in your experience. I was trying to get the mark to straddle the center.

My 85 heads have a pushrod guide hole in the iron head.

It seems to be the consensus that if you are tightening the nut only 1/2 to 1 turn after the rod snugs up, then you won't have to worry about collapsing the lifter.

In another post someone said that when you remove the tension on the rod the spring in the lifter will push it back up, if any bleed down occurred. So you can keep adjusting your pushrod without worrying that you are setting lash on a collapsed lifter. That was what I was worried about.