|
By JimNNN - 4 Years Ago
|
Hi. This is my first post and I'm glad to be here. I posted this question over at the Ford Barn, but one of the more knowledgeable folks over there suggested I post it here.
When I first bought my '54 Ford wagon it had been started after sitting a long time by the previous owner. Because of build up or maybe a bit of corrosion, the valves were sticking and a few of the original push rods were bent as a result. I straightened them out and ran them until there was no longer an issue with sticky valves. This was several years ago (don't drive my car all that much) so at the time I bought a whole set of new Elgin push rods (part # PR-71s) that were specified for 1954 239 y-block.
I just now decided to put them in the engine, but I now notice that they're different than the originals. My friend at the Ford Barn says they're probably an upgraded and improved push rod that's thicker than the original, but they're also about 1/8" longer than what the originals in my '54 239 y-block are. That added length makes me worry that maybe they aren't the correct pushrod, even though they're what Elgin specifies for my engine and what the vendor sold me back when I bought them. There looks to be more than enough adjustment in the adjuster screw on the rocker arm to make up for the added length of the push rod, but I don't know if there are other considerations. Do you think it's the correct replacement rod? My Ford Barn friend says they're 8 - 17/64" long according to Elgin. I'll try to include a pic. THanks for any help you can provide. 
|
|
By charliemccraney - 4 Years Ago
|
The 1/8' difference may only be due to the difference in the design and would be overall length, rather than effective length.
The easiest thing for you to do is install one and see how it looks. The adjuster screw should neither be all the way in nor all the way out with lash adjusted properly and you probably want at least a couple thread exposed under the rocker. If that looks good, then it should be fine.
You can measure the effective length by dropping a 5/16 or 8mm bearing ball into the cup, measure the total length of the pushrod and ball and then subtracting the diameter of the ball.
|
|
By Ted - 4 Years Ago
|
Welcome to the site.
Charlie is correct in stating that you do need to compare the effective lengths of the pushrods instead of the overall lengths. The overall length measurements will tend to vary between manufacturers even when the effective length is the same and that’s simply due to differences in ‘cup’ depths. There is some leeway in effective lengths as the rocker adjusters can compensate for some variance.
I will add that the tubular pushrods are now the normal replacements for the Ford Y. Ford started using the 5/16” pushrods in the ’63-64 engines in lieu of the formally used solid ¼” pushrods. Any kind of performance upgrades to the Y typically has the earlier ¼” pushrods being changed out to the stronger 5/16” pushrods.
|
|
By JimNNN - 4 Years Ago
|
Thanks a bunch Charlie and Ted. I believe that there is probably still an overall difference in what you refer to as effective length between the two, as I removed one of the ball-tipped adjusters from a rocker arm and fitted it to both a new and an existing push rod "cup" and (using a mark on the adjuster ball tip) I could see that it went into the cup the same distance on both push rods. Nevertheless, I'll measure the lengths per Charlie McCraney's instruction and see what I get. I think I might also call Elgin to make sure I got the correct push rods in the new set, too. Thanks again.
|
|
By DryLakesRacer - 4 Years Ago
|
|
17/64 is .265. I found 3 different lengths listed on the net and one was .258…… close enough for me.
|
|
By JimNNN - 4 Years Ago
|
Just to let you know, I installed all of the new push rods and they seem to be working fine. Did a preliminary lash adjustment, and will do a final lash adjustment when the engine is hot. Thanks for your help!
|