So im about to order some 11/32 pushrods from frankenstien but trying to decide which length. using the comp cams pushrod checker I came up with a length of 7.325, then add the .050 preload for my morel drop in lifters and that gave me exactly 7.375. So out of curiousity I measured my checker with a caliper but came up with 7.347, add the preload and that comes up to 7.397.
So im stuck between ordering the 7.375 or the 7.4's. how big of a difference can these two pushrods make by being that small amount too short or too long I guess is what im wondering. Thanks for input

 

Did you add a cam?

 

yeah im doing a complete rebuild, motor is on a engine stand. its a tick torquemaster sns 2 cam

 

Do plenty of reading on this, if you are working on an Aluminum block take into consideration
the expansion of the Aluminum which IIRC will open up the measurement some more. Lots
of reading and opinions on this matter. And when you order tell them how you got the
measurement.

 

Their website sells that cam as a package with springs, retainers, and push rods, the length is 7.400

 

That would differ depending on head gasket used and head work

 

7.4 is stock length. You would do yourself a huge favor by checking for the pushrod length you ACTUALLY need. You will thank yourself later...

 

running a cometic .030 head gasket. I have checked for length with the comp adjustable length tool. by counting the turns on the checker I came up with 7.325, but then when measuring the checker tool with a caliper I came up with 7.347. then add the .050 of preload for the lifter that comes up to a 7.375 with the checker and 7.4 by the caliper reading.

 

Check post 5 in this thread https://ls1tech.com/forums/generatio...ath-check.html. Easier for me to copy and paste than to type. But easiest method is use your checker to find zero lash, measure that length and call Manton. Tell them the length you measured with desired preload and they'll have them to you in under a week prob.

 

Measuring with calipers will always come up longer than advertised length. All my 7.35 pushrods measured anywhere from .017 to .024 longer than 7.35. Basically all pushrods will measure anywhere from .016 to .024 longer than advertised length. The 7.375 are the ones you want.

 

The lengths are actually the same. The stamped length on the pushrod is the gauge length and the measurement with the caliper is the overall length. Two different measurement methods to define the same pushrod. They typically differ by approximately 0.017" with the overall length (caliper) being longer.

 

It's been answered already, but the caliper length is longer than the gauge length. However, it's very easy to mess up the gauge length and very easy to nail the caliper reading, which is why i prefer it. When ordering from a vendor, I use the caliper length, but I also specify "as measured with a digital caliper" for clarity. Some vendors like Manton do them on caliper length. Others will convert to gauge length. On a LS7 or similar lifter, if you're off by .005-.010, it's not a big deal. Others, like Johnson short travel, you gotta be within .005.

In your case, 7.375 should be fine, but if you want, order both 7.375 and 7.400. Then, if your valve train is a bit noisy, you can swap to the longer ones. Return the ones you don't end up keeping. It's way faster than returning and waiting for replacements.

And FWIW, the stock length is 7.385 gauge length and right at 7.400" on a caliper.

 

I get that i just like the caliper measurement because it is more accurate then counting turns. I remember when i first measured the pushrods i bought and i at first i was surprised at the difference in measurements until i realized they were off by thousands which isn't very much.

 

?? I just installed Trick Flow pushrods, which are supposed to be "7.425 overall length" according to summit, which I guess means what you'd measure with a caliper. Well my digital caliper isn't long enough to measure that directly, but I measured one against a stock pushrod by lining them up on one end and measuring the difference at the other end which came to .040 which is what I expected because I thought the stock ones were 7.385. For my purpose I was only interested in the difference, to adjust for the difference in cam base circles (.043, radius) that I measured directly.

 

Wish i wasn't traveling. I'd measure the stock ones I have in my garage and verify.

 

Summit likely sells pushrods made by Trend (Comp and Trick Flow do) and the stamped number is the gauge length since that is the measurement that is used by Trend. I recall getting the same 7.385" length for the stock pushrods as Darth_V8r many years ago, but I don't recall if that was overall or gauge.

Just for the record, most of the people on the phone at some of the larger vendors (Summit) have no clue what the difference is and really aren't qualified to answer technical questions IMO. I am in awe at some of the stupid answers I have received over the years. I would personally rather be told they don't know the answer than be given a wrong one. Best to verify with your own measurements to avoid confusion and issues.