3/8" or 7/16" pushrods

[toad490]

Which should I use 3/8" or 5/16" pushrods in my 493" stroker? I have a .575 lift hydraliuc roller cam, titanium retainers and keepers, stainless roller rockers. Spings are dual with a damper, 140 lbs closed and 434 lbs open (@.700 lift).

[dwc43]

7/16 without a doubt. Smaller push rods flex more and more as the rom goes up and introduces harmonics and false valve motions into the picture. Cost you hp.

[toad490]

Sorry guys I ment 5/16 or 3/8. Had brain fade when I did the title.

[Clair]

You might want to give Smith Brothers a call and see what they say. I was talking with them last week about pushrods, and I think I remember saying that they had some 5/16" CrMo heat treated rods that would hang with that kind of spring. I'm not sure if Smith Bros. carried them, but Comp sells tapered rods that are fatter in the middle and supposedly handle some harmonics better. The trick (IMHO) with any fatter pushrod is making sure you've got clearance in the head to run them. On my 340, the pushrod holes on the 976? heads are pretty small, so running a 3/8" pushrod would be tight. It would also be slightly heavier, unelss they were thinner material. Better to check with the experts.

Clair

[FC7GTX]

Originally Posted by Clair

You might want to give Smith Brothers a call and see what they say. I was talking with them last week about pushrods, and I think I remember saying that they had some 5/16" CrMo heat treated rods that would hang with that kind of spring. I'm not sure if Smith Bros. carried them, but Comp sells tapered rods that are fatter in the middle and supposedly handle some harmonics better. The trick (IMHO) with any fatter pushrod is making sure you've got clearance in the head to run them. On my 340, the pushrod holes on the 976? heads are pretty small, so running a 3/8" pushrod would be tight. It would also be slightly heavier, unelss they were thinner material. Better to check with the experts.

Clair

Well said!!!!

I had clearance issues with my 3/8 push-rods and the Edelbrock heads.

[skankweirdall]

I had major issues putting 3/8 rods into my W5's. Nothing that wasn't unsurmountable though. Go with the 3/8 but check every one.

[toad490]

I've got a nice set of 906 heads on my 383 that I'm going to use, is there enough meat there to make room for them?

[FC7GTX]

My guess is the 906's will be just fine for the larger push-rod. As you can see in the attachment the cavity for the push-rods (Edelbrock Head) are small round circles, not the big hole(cavity) that the 906's have so clearance is more of an issue with the E-heads especially with 1.6 rockers and 3/8 push-rods.