2003 Z06 with Livernois Stg 3 243 heads and 290 292 592 595 lll LSA cam. I measured the pushrods and need a 7.375, should I go with 3/8 or 5/16 rods?

Thanks

 

If the 3/8 will clear they offer improved rigidity. I would also look at 11/32 Manton's which are pretty stout.

 

please pardon the ignorance, but clear what? Is the limiting factor the passage in the heads? If it matters, Im running LS7 lifters and the stock rockers with the comp trunion upgrade. Im assuming the factory units are 5/16s? The pushrods I installed with the cam a few years ago were MTI chromoly 7.4 .080....not sure what that translates into as far as pushrod width

 

Yes, the limitation is the clearance between the pushrod and the head. It does not require a lot of clearance, but the pushrod should not actually rub the head.

 

Ask Livernois; I think the 3/8 will clear and a beefier pushrod to minimize deflection is most definitely better.

 

3/8" wouldn't clear my AFR heads, but the 3/8" double taper did. Clear benefit in the upper RPM with the stiffer pushrods. 11/32" mantons are an option if the 3/8" won't clear or the double taper but I don't know if they will clear. The double taper is exactly for that reason, clearance at the upper and bottom ends. I have Trends that were machined out of solid billet steel. Very nice pushrods. I have a write-up on them as well.

 

How do you determine a happy medium for strength and weight? Should I go for tapered? I currently run 11/32" Manton pushrods. I am not sure if 3/8's will clear. However, I run LS7 lifters, PAC 1518 springs and a blower cam. My shift point is 6500 or slightly less (I want to keep my stock bottom end together as long as possible). The car makes around 550 rwhp with the procharger. I will be swapping cams and will need to remeasure and order new pushrods.

 

Heavy wall 5/16ths (like .105") will be fine and will clear, but the 11/32ths with the .135" wall will be even better, but ask Livernois to make sure.

 

3/8 mantons clear most factory castings..

 

My builder tells me that pushrod ridgity trumps weight every time.

 

And he's right .. Valve train is where the magic happens..

 

is there any good way to tell if they will clear? I imagine while the car is running the clearance might be a hair tighter to the head?

 

3/8" all the way.

 

HKE lists their branded pushrods (which I assume are Manton customs) as clearing factory heads with factory rocker arms for the 3/8"... Why wouldn't it work with roller rockers as well?