John
Active Member
A friend came over to measure pushrods for a SBC going in my truck. He used a Comp Cams adjustable pushrod I bought for the job, one of the hydraulic lifters that will be used in the motor (Comp 812-16), and 12" digital calipers I have. I've never done this before but read up on it and watched several youtube videos just to learn what I could about what needed to be done to do this right. The intake is not on the motor yet, making this job a little easier. This is a shortblock I ordered with the heads installed but no oil in yet, just assembly lube.
So that said, using zero-lash method, after some adjusting, we got a great wear pattern centered on the tip of the valve stem and arrived at "the number." 7.996" if it matters. I'd already called Comp Cams Tech line once and was told the lifter I'm using pumps up .030". So before I spend $165 on custom pushrods, I called them back to walk through the numbers and make sure I'm placing the correct order.
So, to cut to the chase, I thought I needed to subtract .030 from 7.996 and order 7.966" length pushrods, and I'm calling them to confirm this. The tech I got (young buck, not that it matters) tells me No, I need to ADD .030 to the measurement.
I've read the link here: http://garage.grumpysperformance.co...-pushrods-and-check-info-you-might-need.5931/ and it's sub-links, admittedly I'm doing a lot of skimming because I'm looking for info on how to properly compensate for using a dry hydraulic lifter when measuring for pushrods.
So.. Is the young buck right? To my way of thinking, I'd end up installing pushrods that are too long that are going to be WAY too long when the lifters pump up. But I'm no engine builder and need some help with this. Thanks+++
So that said, using zero-lash method, after some adjusting, we got a great wear pattern centered on the tip of the valve stem and arrived at "the number." 7.996" if it matters. I'd already called Comp Cams Tech line once and was told the lifter I'm using pumps up .030". So before I spend $165 on custom pushrods, I called them back to walk through the numbers and make sure I'm placing the correct order.
So, to cut to the chase, I thought I needed to subtract .030 from 7.996 and order 7.966" length pushrods, and I'm calling them to confirm this. The tech I got (young buck, not that it matters) tells me No, I need to ADD .030 to the measurement.
I've read the link here: http://garage.grumpysperformance.co...-pushrods-and-check-info-you-might-need.5931/ and it's sub-links, admittedly I'm doing a lot of skimming because I'm looking for info on how to properly compensate for using a dry hydraulic lifter when measuring for pushrods.
So.. Is the young buck right? To my way of thinking, I'd end up installing pushrods that are too long that are going to be WAY too long when the lifters pump up. But I'm no engine builder and need some help with this. Thanks+++