Small block pushrods with hydraulic cam.

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toolmanmike

toolmanmike

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Desert Rat and I have been talking about which pushrods to use when changing a 273 from solid to hydraulic cam/lifters. I have been looking at old threads and found 5/16" Ball/cup pushrods that are 7.342 long. (7 11/32") I know there has been discussions about what works and even part numbers for the correct pushrods. Please don't hesitate to post your success stories including dimensions and part numbers. We could use a sticky on this. It seems to be asked often. tmm
 
TMM, give me a couple of days and I'll look in my stash and see if I have some.
 
that is what i use with hydraulic lifters with adjustable rockers..
 
I have the rockers, shafts, pushrods, the who works for 50 shipped, also rockers, like i said the whold hyd deal.
 
Hmmmmm----Almost a mistake of epic proportions! I just measured my stock 273 solid lifter pushrods and they are 7 15/32" or 7.46875" from top of cup to end of ball. I stumbled on a comment by TMM in another thread that mentioned shorter pushrods when changing from solid lifters to hydraulic lifters in a 273. The brain trust on this site prevented me from an error that would have cost me some money! I elected to go with a Lunati #60401 cam with Comp lifters and valve springs for my build. I guess I will be ordering new pushrods for my engine soon. Thanks all, I really appreciate the input from everyone!
DR:D:stop:
 
The reason why the pushrods for the hydraulic lifters are shorter is because the pushrods engage the lifter about a third of their dimension from the top. The lifter on the left is a hydraulic and needs a shorter pushrod because the piston where the pushrod contacts is higher in the lifter body and closer to the rocker arms so therefore needs a shorter pushrod. tmm
 

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Are we talking hydraulic cam with solid,adjustable rockers ?
 
My plan is to use the hydraulic lifters and magnum pushrods with the stock 273 rockers and adjustable rocker arms. Is there another problem with doing that?
 
DesertRat said:
My plan is to use the hydraulic lifters and magnum pushrods with the stock 273 rockers and adjustable rocker arms. Is there another problem with doing that?
Click to expand...

Magnum pushrods from a mopar magnum engine are way shorter then a LA pushrod due to the taller hydraulic roller lifter....

if you are talking about compcam magnum rockers for LA engine...just get the correct length
 
70aarcuda said:
Magnum pushrods from a mopar magnum engine are way shorter then a LA pushrod due to the taller hydraulic roller lifter....

if you are talking about compcam magnum rockers for LA engine...just get the correct length
Click to expand...

I think he was talking about the Comp Magnum pushrods for the LA engine.
 
Again.....Hydraulic rockers or Solid/Adjustable rockers ?

Unless you clarify, this thread will be all over the map with misinformation.
 
Only safe and sure method is to measure for what length you need.
There are too many variables to call out a set length.
 
DesertRat said:
My plan is to use the hydraulic lifters and magnum pushrods with the stock 273 rockers and adjustable rocker arms. Is there another problem with doing that?
Click to expand...

Stock adjustables Johnny Dart
 
RedFish said:
Only safe and sure method is to measure for what length you need.
There are too many variables to call out a set length.
Click to expand...

I'm using huhges roller rockers, Comp Cam hyd cam, MP lifters, LA340, J heads and Summit G6420.......340 TA, AAR pushrods were a perfect fit.
 
DesertRat said:
Hmmmmm----Almost a mistake of epic proportions! I just measured my stock 273 solid lifter pushrods and they are 7 15/32" or 7.46875" from top of cup to end of ball. I stumbled on a comment by TMM in another thread that mentioned shorter pushrods when changing from solid lifters to hydraulic lifters in a 273. The brain trust on this site prevented me from an error that would have cost me some money! I elected to go with a Lunati #60401 cam with Comp lifters and valve springs for my build. I guess I will be ordering new pushrods for my engine soon. Thanks all, I really appreciate the input from everyone!
DR:D:stop:
Click to expand...

If you want to save a few bucks on the cam I have a low millage used one with lifters marked for the lobe they came from. pm me if intrested
 
You can convert an old 273 to hydraulic rockers and cam by just using stock LA style (pick a year - like 1970 318) and get the same rockers and push rods as a stock 70 318.
 
Johnny Dart said:
So what you need is a TA or AAR 340 pushrod.

Hydraulic cam adjustable rockers.

Summit G6420 fits the bill.
Click to expand...



Are you sure? The T/A heads had different adjustable rocker arms than the 273. Will the pushrod length work with the different geometry?
 
When I put in a hyd. cam using my stock adj. rockers 20 years ago, I had to order cut-to-length custom pushrods. It's possible there are more options now. But I don't think the 340 TA pushrods can be the answer, or I would have found them back then.
 
Why not make it easy and just run hydraulic pushrods and stamped stock hydraulic rocker arms?
 
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