There are tons of threads on this and a lot of inconsistent answers but I wanted to ask anyway because I just placed an order and may call to change it before it ships. I have a TSP 228r cam on order and went with 7.4 pushrods but after reading I’m now considering on changing the order to 7.35 pushrods because I am having a set of ls7 lifters put in also. I understand the only way to know exactly what length you need is to measure, and im sure the shop doing the work for me will do that, but like I said I am having to order the parts so I would prefer to have the correct part ordered the first time. Again the cam is a tsp 228r, stock 243 heads and GM gaskets. I would prefer as little valvetrain noise as possible, so with the ls7 lifters having a slightly more shallow cup would I be better off ordering the 7.35” pushrods and going from there or stick with 7.4?

 

I'm not going to tell you to measure yourself based on what you have posted.

Stock heads, stock gaskets, ls7 lifters and a normal cam. 1.740"

 

Why can't the shop measure and then put the correct length in? Can't tell you how many customer supplied pushrods went home with them because they weren't the right length.

I would suspect a 7.375 to be too short.

 

if they wont properly do it... you need a new shop..... Ls engines are finicky when it comes to proper pushrod length..... the whole purpose is to get the proper wipe pattern from the rocker to the valve tip.... with an old school small block the rockers were on a stud and lifter preload was set by running down the rocker … because the LS is a "pedestal mount" it has no adjustability.. therefore proper lifter pre-load is set my Pushrod length..... you will have changed 3 variables in the equation…. 1. the cam circle may possibly be different from stock with an aftermarket cam. 2 a different lifter entirely....and 3 the pushrods themselves.....… for peace of mind... have the shop do the proper thing and check pushrod length...

 

Maybe I wasn’t clear in my post. This has nothing to do with the shop that will be doing the install, they are a reputable business and I’m sure they will measure and advise me correctly on what length pushrods I need. What I was saying is that I am ordering all the parts myself and supplying them to the shop that’s doing the install and would like to provide the them with the correct length pushrods so that I don’t have to have them sent back for different ones. The pushrods are part of the cam package so I have to get them...I get that you Need to measure to know for sure what length to get but Obviously I am not doing the work myself, therefore I cannot just run out to the garage and measure..I am having the lifters put in at the same time as the cam. I’m sure that once measured if I need a different length then what I have ordered Texas Speed will allow me to send them back and exchange for a different length, hopefully, but like I said it would be nice to at least shoot for the correct length from the start, that was the purpose of the post. Not sure what is so difficult to understand about that...

 

You would have to measure the pushrods with the heads on the car with the lifters you plan on using to be 100% sure of the length needed. Different lifter require different preload and plunger height./cup may not be the same from lifter to lifter model. As ASROFF posted cam base circle, lifter, head gasket and cylinder heads (including if they've been decked) all play into the pushrod length and the rocker is not adjustable. The LS7 lifter does have a relatively large preload window when compared to other aftermarket
lifters.

If you want to run with the assumptions that the cam base circle is as TSP lists it, and the heads have never been decked, I could call TSP and give them the list of parts you're using. I agree with ASROFF measure then order pushrods.

Vettenuts had a great topic on measuring pushrods and I would recommend 11/32" pushrods, BTR and Summit both offer reasonably priced 11/32 pushrods, if the heads are ported and clearanced go with 3/8" pushrods.

 

I'd go with 7.4 or 7.425 for a non milled head set up. Based on my experience 7.375 will be too short.

 

FWIW, A friend and I did heads and cam, 243s very light decking for cleanup, Morel Drop In lifters (5290?), and a CamMotion Cam. It took 7.375s and a few track days later is running great.

I'd measure.....

 

It sounds like his shop will be measuring and hopefully what he provides is correct. With ls7 lifters and completely stock heads and factory gasket I don't think I've ever ended up below a 7.4" pushrod.

Side note, pushrod length does not change the swipe pattern as mentioned in another post. It only changes lifter preload.

 

The only reason I questioned the 7.4” is because apparently these ls7 lifter cups sit .050 higher than my factory lifters so I assumed I may need a 7.35 pushrod, but then again I really don’t know much about motors so like you mentioned I will make sure the shop measures and points me in the right direction. I just don’t want a crazy loud valvetrain and obviously don’t want anything getting excessive wear or breaking. But yea completely stock 243 heads, stock gaskets and ls7 lifters.

 

You can get away with 7.4, but 7.35 is optimum because of the higher lifter cup. I measured mine with ls7 lifters and a pushrod checker, and came up with 7.35 with stock rocker arms.

 

Let them measure, and then you can order them. Simple as that.

 

I’ve read an article or two that indicate running the lifter cup a little lower, i.e. longer pushrods, yields more power, apparently due to less air filled oil beneath the cup.