7/16" pushrods...

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May 5, 2023 | 12:04 PM

grinder11

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7/16" pushrods...

Anyone tried running 7/16" diameter pushrods in OEM LS7 heads? Will they clear, or is 3/8" the max you can run?. TIA.....

May 5, 2023 | 12:09 PM

G Atsma

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What would be the point in doing so?
3/8" pushrods are plenty strong for the stiffest springs commonly used in full effort LS apps.

May 5, 2023 | 12:32 PM

grinder11

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Quote:

Originally Posted by G Atsma

What would be the point in doing so?
3/8" pushrods are plenty strong for the stiffest springs commonly used in full effort LS apps.

I'm running stiffer duals. Stiff pushrods can't hurt a thing, as long as they clear. I'm either going with .105" or .120" wall 3/8", or .105" wall 7/16"

May 5, 2023 | 08:29 PM

Che70velle

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The pushrod is the second spring in the valvetrain. Lots of flexing going on with all but the stiffest pushrods. Flexing pushrods reduce max lift at the valve, can add to lifter body wear, and make it hard on valvesprings. The flexing isn’t a big deal…or issue…with a super mild low rpm build, but can become a factor with big effort builds, especially in solid roller applications.
Mike, I’m final cleaning a set of GM LS7 heads in the shop this weekend, and I have 7/16” pushrods in stock. I’m doubtful they will work without clearancing, but I’ll check it out for you.
Fo what it’s worth, there are guys here on Tech running 9/16” pushrods…

May 6, 2023 | 01:49 PM

grinder11

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Quote:

Originally Posted by Che70velle

Thanks, Scott. I checked with Manton and Trend, and they both thought 7/16" wouldn't work without clearancing the heads PR holes. As of right now, I'm not sure what length I'll need. I have OEM length Trend 7.800x3/8"x.080" wall. Heads cut .020", so I'm thinking 7.775" long PRs. But until I measure, I won't know for sure.

May 10, 2023 | 07:49 PM

jayyyw

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I believe 3/8 is the largest you can do without opening up the pushrod holes. I've found wear on the pushrod "body" with 3/8" pushrods in a LS7 head. So it was touching something.

May 10, 2023 | 08:02 PM

Che70velle

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I forgot all about posting back up in here Mike, my bad. 7/16 rods will drop through the holes, but won’t work because the rocker moves on an arc motion, which moves the pushrod north and south during its stroke. I don’t think it would take very much work at all to make them work, imo.