67barracuda
Well-Known Member
Anyone have a good way of measuring the correct length for custom ball and cup push rods? I have the adjustable ball and cup push rod tool, I just can't remember what I did last time.
measuring for custom push rod length
- Thread starter 67barracuda
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Coronet 500
Well-Known Member
If you have checked geometry for valve stem pattern and allowed for hydraulic preload or solid lash, then you have your adjustable rod set, drop a 5/16" ball in the cup measure total then subtract ball.
This will give you effective length, be sure your supplier uses the same terminology as you and understands your measuring technique as there are a number of different words used to describe length.
This will give you effective length, be sure your supplier uses the same terminology as you and understands your measuring technique as there are a number of different words used to describe length.
When I built dad's Hemi, I had a friend at a machine shop take two pushrods and cut them in half, then thread them and put threaded rod in them, so now the pushrod length was adjustable.
Then I put each pushrod in each position and adjusted the rocker arm stud 2-3 tuirns and then brought the pushrod to length needed to accomodate this distance. Then I measured each of them and took an average for each position 5 times. Then averaged the length for intake and exhaust. Found my target lengths and then bought a full set of cut to match pushrods and had them made to the proper lengths for intake and exhaust pushrods (they are different on a Hemi).
Then I put each pushrod in each position and adjusted the rocker arm stud 2-3 tuirns and then brought the pushrod to length needed to accomodate this distance. Then I measured each of them and took an average for each position 5 times. Then averaged the length for intake and exhaust. Found my target lengths and then bought a full set of cut to match pushrods and had them made to the proper lengths for intake and exhaust pushrods (they are different on a Hemi).
Treblig
Well-Known Member
Krazykuda...you've just saved a bunch of folks some money!!!!
Brilliant!! That is a very ingenious way to get "dummy" adjustable push rods. I have a set of "dummy" adjustable rods save on my ebay list. I was planning on buying them as I build my 318 stroker but since I'm a machinist I can easily make one of those "homemade" dummy rods very easily. I thought that the push rods were hardened and couldn't be easily drilled and tapped but now I know different!!
One question....do the (hydraulic in my case) lifters need to be pumped-up for the push rod length check. How do you know when the lifter begins to collapse. That's the part I'm sure of???
Don't mean to get off subject but I haven't found the answer to my question anywhere.
Thanks,
Treblig in Tex
Brilliant!! That is a very ingenious way to get "dummy" adjustable push rods. I have a set of "dummy" adjustable rods save on my ebay list. I was planning on buying them as I build my 318 stroker but since I'm a machinist I can easily make one of those "homemade" dummy rods very easily. I thought that the push rods were hardened and couldn't be easily drilled and tapped but now I know different!!
One question....do the (hydraulic in my case) lifters need to be pumped-up for the push rod length check. How do you know when the lifter begins to collapse. That's the part I'm sure of???
Don't mean to get off subject but I haven't found the answer to my question anywhere.
Thanks,
Treblig in Tex
Treblig
Well-Known Member
70aarcuda,
Perfect...just what I needed. You guys (and Gals) are great!!
Treblig
Perfect...just what I needed. You guys (and Gals) are great!!
Treblig
67barracuda
Well-Known Member
Ok, I've measured a couple of times and I got 7.455" for total length(top cup to bottom ball)dose this sound right?
I have Indy T/A heads with adjustable roller rockers, and running a hydraulic cam. Now eveything I read about adjustable roller rockers, it looks like everyone is running 7.500" pushrods. Is 7.500 to long, did I measure wrong? I left 1 thread showing between the ball at the end of the stud and the bottom of the roller rocker.
I have Indy T/A heads with adjustable roller rockers, and running a hydraulic cam. Now eveything I read about adjustable roller rockers, it looks like everyone is running 7.500" pushrods. Is 7.500 to long, did I measure wrong? I left 1 thread showing between the ball at the end of the stud and the bottom of the roller rocker.
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