Small block pushrods with hydraulic cam.

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krazykuda said:
Are you sure? The T/A heads had different adjustable rocker arms than the 273. Will the pushrod length work with the different geometry?
Click to expand...

T/A intake rockers were offset, exhaust were straight like 273 rockers. Measure to be sure. There are a lot of variables. How close you get to perfect matters, especially at higher lift and rpm. Places like Trend Performance, http://trendperform.com/measuring/ , have easy to use checking pushrods.
 
Thanks all for the help. Thinking about the oiling situation I have another question. My solid lifter stock pushrods are closed at both ends so no oil can go through them, the rockers oiling from the rocker shaft. The pushrods I need the correct length for hydraulic lifters are hollow which I assume will allow oil to travel through them to the rocker tip. Will this happen and will if have unintended consequences which will be bad for my build?
DRO:)
 
krazykuda said:
Are you sure? The T/A heads had different adjustable rocker arms than the 273. Will the pushrod length work with the different geometry?
Click to expand...

340 T/A AAR used a hydraulic cam.
273 used a solid cam.
So, no. Totally different pushrods.

Im building a 340 hydraulic cam, adjustable rocker motor as we speak. Through my research, 340 t/a pushrods are what you need to use. Despite having offset rockers on the 340 t/a heads, all the pushrods are the same length. The Summit pushrods I mentioned are suppose to be the hot ticket for this combination. I will report back when I get the valvetrain installed.
 
DesertRat said:
Thanks all for the help. Thinking about the oiling situation I have another question. My solid lifter stock pushrods are closed at both ends so no oil can go through them, the rockers oiling from the rocker shaft. The pushrods I need the correct length for hydraulic lifters are hollow which I assume will allow oil to travel through them to the rocker tip. Will this happen and will if have unintended consequences which will be bad for my build?
DRO:)
Click to expand...

Whether oil travels through the pushrod to the rocker cup depends on your lifters. Chrysler style lifters will not pump oil to the lifters through the pushrod. AMC style will, either will fit and work. I do not know of any bad consequences of having both oil the rockers or using hollow push rods without flow through lifters.
 
Thanks guys, I will go ahead and order the TA lifters and keep augering on! My lifters are Comp with matched valve springs for the LA engine so I think I am good!:coffee2:
 
Well I have narrowed it down to two choices of pushrods. The Summit #G6420 which is 7.234" long, non heat treated steel non oiling 5/16" cup & ball for $43.97 per set, application universal.
Or Comp #CCA-7692-16 which is 7.342" long, chromemoly steel non oiling 5/16" cup & ball for $107.97 per set, application small block mopar.
So there is either a typo on the Summit units or they are .108" shorter than the Comp unit.
My build is designed for 5000 RPM and equivalent to the 235 HP 273 with possible a small increase in power. I think the adjustable rockers will handle the difference in length but for some reason I am struggling with the decision. I guess I will throw the dart and make a decision soon. Been an interesting learning experience for sure!:coffee2:
 
Companies use different ways for listing length.
Comp Cams listings uses the Gauge Length Method.
Different method is most likely what your seeing.
http://www.cpgnation.com/forum/threads/comp-cams-pushrod-tech.2408/

On a ball/cup I use a length checking pushrod (old pushrod cut and 10/32 threaded rod to adjust proper length) Remove from mockup and place a 5/16" ball in the cup. Measure total length and subtract 5/16". That number will give you the length from the bottom of the cup to the end of the ball. Smith brothers can use that number to make custom pushrods for you.

Deck height, lifter preload, head gasket thickness, head milling in the past, and rocker arm all effect proper pushrod length. Pushrods are the last item to order when building a motor.
 
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