340 push rods

[americal]

Hello everyone. I am confused by the different lengths in push rods for our engines. What is the actual length for stock 72 340?

 

[Locomotion]

Hello everyone. I am confused by the different lengths in push rods for our engines. What is the actual length for stock 72 340?

I don't recall for sure about the actual hydraulic (ball-ball) pushrod length, but all hydraulic cam LA small blocks come with the same length pushrods.

The adjustable rocker cup-ball pushrods for the early 273 solid lifter enginesare 1.500" while the adjustable hydraulic 340 6 Pack engines are around 7.21 or 7.23".

Comp sells a length around 7.3-something as a compromise between adjustable solid & hydraulic set-ups, but you have to be careful there. Decked block & heads can be a factor in finding the correct length.

FYI - With adjustable rockers, solid lifters have their pushrod cup deeper inside the lifter and require a longer pushrod than an adjustable rocker set-up with hydraulic lifters.

 

[70aarcuda]

Ball to Ball length pushrod is right around 7.5 inches...which would be for a stock LA engine with non adjustable rockers and hydraulic lifters.

 

[americal]

thanks for the info. I looked up information about push rod length and I thought 7.500 was standard length for all the LA engines but it also said that 7.514 was the correct length. I couldn't find a push rod that length but I found a 7.513 for magnum engines. This all seemed strange to me that all LA engines could use different size push rods.

 

[JBurch]

Push rod length for stock 1972 340 is 7.534 inches per "How to Hot Rod Small Block Mopar Engines" by Larry Shepard

 

[americal]

OK I have another question. I have comp cams valve springs part no. cca-901-16. I was going to use my stock 72 valve spring retainers but Summit tech department said they wont work.They said to use comp cams cca 740-16 retainers. Does any one know any thing about this?

 

[Locomotion]

I don't know how the OEM retainers will fit the Comp Cams springs, but I was told that the fit should be close so the spring doesn't move laterally under the retainer.

You could get by with a 7* version of the retainer & corresponding locks, but if you go with the 10* lock 740-16 retainers, I have a new set to sell. PM sent.

 

[americal]

Ok guys I got in contact with Comp Cams. They recommended 604-16 locks and 744-16 retainers. I have 7 degree 4 groove valves. So I will go with that. Thanks Locomotion for the offer.