What diameter, lobe, ratio, lifter??

The Ripper has a Smith Bros 5/16 .120 wall

.450 lobe intake 1.6 ratio, .440 lobe exhaust 1.5 ratio

.842 fairly light Crower roller lifer.

After a very long phone call with Al at Manton pushrods several years ago, my input is this:

Largest diameter you can physically fit in the engine. Straight wall is best, tapered if needed to clear ports, etc.

Tubing thickness is second. If you can't get diameter, get thicker tubing.

Also use the strongest material available. 4130 moly is entry level.....I personally use Manton series 5 material for mine.

Pushrod weight is not a consideration, it has little effect on valve action, unless it's too small or to thin or to weak of material. pushrods can cost power, cause issues with valve train, and can fail when you least expect.


They build more pushrods than just about anybody out there next to Smith Brothers and Trend, and have more data about what a pushrod does than you can imagine.

These are Manton ball adjuster pushrods, super nice pushrods.

I agree with most of the points you made, I think you want rigid, but the heavier the pushrod, the further out in left field you can get with valve springs, to manage the weight.

I might try an 11/32 .80 wall, we have a guy local here in Fl. building our pushrods now, Denny Steward. Really convenient, nice product. I may try them to see if there's anything to be gained.

Do you think an 11/32 .080 wall would be more rigid than a 5/16 .120 wall, even though it'll be lighter, using the same material? I do.

quote:

I do.

Me too. Like the man said, dia. is king. Certainly is in quality bicycle frame design. Color me old fashion, and uninformed, but I still favor old fashion rev kits. They take the weight of the lifter off the valve spring (now more spring available for the pushrod) and if things go south the lifter stay and the bore and oil pressure is maintained. Flame on.

quote:

Originally posted by Canted Valve:

quote:

I do.

Me too. Like the man said, dia. is king. Certainly is in quality bicycle frame design. Color me old fashion, and uninformed, but I still favor old fashion rev kits. They take the weight of the lifter off the valve spring (now more spring available for the pushrod) and if things go south the lifter stay and the bore and oil pressure is maintained. Flame on.

It's a pretty decent lil brain-twister question, I think.

Every little bit helps when it comes to the torque diminishing at a lesser rate than the RPM is increasing - Power.

This message has been edited. Last edited by: Mike Rietow,

I can tell you this, despite what I'm running for pushrods, you can see witness marks where they are rubbing my ports from flexing. Next freshen I'm going to make more room and put bigger ones in. I'm running 3/8-7/16 single taper on the intakes (to clear the ports), .210 wall, and straight 1/2", 210 wall on exhaust. Going to more offset on the lifters, unless I can find the cash to do keyway and a different cam, 9/16" on exhaust and 1/2" on the intakes. That's gonna be a fun bill to pay for...

In one of our sponsored 434s that we put in our 80 Camaro in 2008. The motor has never been back out of the car & have only replaced valve springs & lifters.

Anyway, from what I can see everything has been built overkill on this motor for only (630hp). It has 3/8 .080 wall pushrods, .430 intake lobe with a 1.6 ratio,.421 exhaust lobe with a 1.5 ratio. It has T&D rocker shafts & nothing trick $700-$800 Lunati roller lifters.

I think my pushrods are .135 wall 3/8"

I built a Big Duke headed 555 probably 15 years ago.

3 different length pushrods with T&D shaft rockers....Over 10" long IIRC on some....

I think I used heavy wall 3/8ths pushrods and they would have been the best you can buy...don't recall what brand.

Valve springs were PAC triples.....cam I don't recall.....

It ran for 2 seasons mostly in S/C but got abused pretty bad as the owner was tough on his equipment.....HAT Injected on Alcohol....

During a rebuild I changed to 7/16" pushrods as it was felt by some engine builder buddies I talked to that the 3/8 might be flexing....

There was no issues in the valve train and no evidence of valve float......engine saw probably 7800 or more at times....but I decided to make the change anyway

The 7/16" pushrods made zero difference.....and I spent a lot of time making room in the heads for them.....

That engine continued to run with no issues......eventually was taken apart and was parted out....

The Big Duke heads never ran great with that Hat Injection......decent and never broke a thing.....even won a Wally for the owner.....

My own engine has Manley 3/8's .120 or .130 wall......never had a problem with them or CC's pushrods either....

My 598 and the 632 conventional head both run the
10.050 push rod lengths. 0.80 wall and never an issue. 1.640 triple also. 10.2 DH. Once i found the correct stud girdle for my 385 CFE head. Designed by CFE/BMF. Valve is rolled 2**. 3/8 PR.

This message has been edited. Last edited by: TD3550,

FWIW, if you're concerned about weight on the lifter side then think about the leverage ratio of the spring pushing back against the pushrod from the rocker arm vs. what the pushrod has to do against the spring. Just a thought.