rskrause

I have gotten into the pro and con of shaft rockers a number of times. I contend that they are generally speaking a waste of money except on max effort motors. Here is what Joe Sherman, multiple Engine Masters winner/runner up had to say about them in the context of 750-800hp BB Chevy's turning 7,500-8,500 rpm, a much more demanding use than 99.99% of the motors here (the guy was asking about whether he needed a hi-dollar crank):

"Spend your money on something that will make more HP, not on things you DONT need at this HP level. The shafts or better crank will NOT make any more HP. The heads and cam is where you make HP.

JOE SHERMAN RACING ENGINES"

Rich

1989TransAm

One thing about Joe is he does not mince his words. He gets right to the point.

With the hours upon hours of dyno testing over a lifetime he has learned a thing or two about horsepower and what works and does not work.

MachinistOne

Yep - Joe knows.

The BBC has much better geometry with regular stud mount rockers than the SBC does. We don't use shaft mounts on our 650-750 hp 502's - just a good stud girdle. The SBC on the other hand suffers from poor geometry which you can see yourself by testing the rotating torque of the motor with the rockers tightened down vs not on the motor. The BBC has a much lower percentage of frictional drag due to the valvetrain as compared to the SBC.

FASTFATBOY

Maintaining correct valvetrain geometry= power. I got shaft rockers on my LT1.

David

mdacton

Wish I could get some....
for this reason......I have 7/16 studs with a girdle. well everytime you set the lash then tighten the girled the bitch pulls the studd back so I get another 8-10 thou lash...so its is a huge PITA to get it right. Maybe I would be better off without the girdle?

Either way...if I had the money I would have the shafts

GreasyB

How much do shaft mount rockers even cost. By the time you add up new studs, the rockers, and maybe a girdle if you want it. How much more do shaft mounts cost?

rskrause

You don't believe Joe Sherman, maybe I need to resurrect Smokey Yunick??? If you were starting from scratch, there wouldn't be a big difference in the cost. In that case, I'd consdier shafties due to the ease of valve adjustment, as mdacton has already alluded to. Otherwise, there is a big difference in cost as most people already have rockers and studs. So, a girdle and nuts for ~$150-200 vs. $900+ for shafties. That don't make any power.

Rich

mdacton

I've been told the $1,000 shaft mounts are not very good at all.

I have seen a few broken jesel rocker arms...they had 400# on the seat. But something about the oiling etc. my machinist said the t&d are the only way to go...possibly cranes.

rskrause

The last set I saw I liked was Crower's for a measly $1,300. I'd put the money into the rest of the top end first and spring for shafties only AFTER I had killer heads, valve springs, intake, custom cam, etc. But I guess you already know that. I have to laugh when I see someone with a HR cam spinning to 6,500 think they need shaft mount rockers. They don't even need a girdle, let alone a diaper ;^)

Rich

ulakovic22

Even if you start out with a clean slate shaft mount are still too expensive for my taste. On my BBC project you can get 7/16 studs, Pro Mags and a girdle in the $500 range.

tgw323

If your adjustment changes a bunch when you clamp down, something isn't lined up right. I've seen this problem with the cheap,cheesy Chinese rocker studs. Or if you got a Chinese girdle,that may be the problem.

mdacton

arp studs, moroso girdle, crower rockers, manton pushrods, cv valves..nothing chinese.

Kevin Blown 95 TA

Horsepower is one thing - I wonder about reliability though. And when I had a RB Mopar, I loved the shaft mounted rocker arms. I always thought that was a better, more solid setup than the stud mounted ones.

quickSS

I don't read into it that Joe Sherman was dissing Shaft Rockers one bit in his quote. He's saying the obvious which is spend your limited money on the heads/cam...and not on billet (super stiff) Sonny Bryant crankshaft or shaft rockers.

But:
Shaft rockers are like everything else good in life, once you try them you never go back to what you had before.

Some people get a kick out of making gobs of power with cast cranks and 2-bolt mains and stockish hardware. And why not have fun with things like that and have at it. Get yourself a flat head Ford and go to town....seems like a fun ecentric project. (A silly motor but a fun motor).

Shaft rockers might not "add" power at our lowly power levels but they make life easier on the motor and the owner for obvious reasons.

And to the Joe Sherman quote I know one thing, all the engine masters making 700/800 hp with Big Block whatevers are all using every trick allowed and especially stiff billet crankshaft so what the heck is he trying to tell someone to NOT use a billet crank when HE is using a billet crank?

Karl Ellwein

rskrause

Karl: you make a good point. I'd like to have them. I was just using Mr. Sherman's comment to corroborate my point made in another thread - that shafties are far from a necessity and really don't add much hp, if any, in a typical combo. If you are running triple srpings with 1000# open, that's one thing. But that is long wway from where most of us are.

Still, if I could just find that winning Lottery ticket I would be on the phone to Crower ASAP.

Rich