Clarifiction 604 Pushrod Length

[brad hibbard]

There seems to be some discrepancy amongst some series officials, tech inspectors, and engine builders about the length of the GM 604 pushrod.

After discussing the subject with manufacturing officials, the actual blueprint for the pushrod was pulled for examination.

The circle track technical manual states a length of 7.122 "inches"
The manufacturing blue print is NOT taken in a end to end procedure
it has a dimension from the tube to a specified spot on the welded ball that (again) is NOT the end
and this total dimension is 181.1 MM to 180.7 MM and when converted to inches comes to
7.11417 inches to 7.12992 inches
when those 2 dimensions are added together and divided by 2 the listed spec became 7.122"
again keep in mind this is NOT an end to end dimension

the original poster on this subject stated in a second post that an actual pushrod measuring 7.122" had been used as an example in tech--I am assuming this was an end to end dimension and
neither myself or my manufacturing sources have an explanation for that particular find
I can only state what the print calls for and what we have found in field research
the actual print leaves an area unmeasured that will easily add enough length to hit the 7.192 end to end mark that we found in all of our research samples (give or take a couple thou)

the newest version of the technical manual has not been finalized and I have been assured that a explanation of "actual" end to end dimension will be added

this has been a great topic of conversation in the fact that it brings awareness to components and helps to clarify some confusion within the tech manual
these types of conversations are how we all get better at our jobs including the people writing the tech books and procedures

thank you to the original poster for bringing this to the table

I do have the pushrod blueprint in hand and can email it to anyone wanting to see it

Brad

https://www.race-1.com

[donavon]

Thanks for getting that clear Brad Hibbard..

[brad hibbard]

Donavon,
I'm not sure my explanation is really "clear" but I did my best
I am not very computer literate and wish I could post the print here but it just won't work in my copy/paste methods

please know that the actual dimension is not taken end to end like most folks would typically measure a pushrod

there should be no big panic to get new pushrods from anyone

I applaud the original poster in bringing the subject to discussion ---
I kind of wish he would have signed a real name as that adds incredible accountability to any subject

Brad

https://www.race-1.com