MP aluminum rocker shaft hold downs

[Mrbill426]

Does anyone have first hand experience with these on J heads, and are they alright to use with the stamped steel rocker arms?  Pros/Cons?

https://www.summitracing.com/parts/DCC-P5249712

[1 Wild R/T]

Purpose is to keep the shaft from distorting, If the shaft distorts the rocker bind... But the stamped steel rockers don't fit the shaft tightly so distorting the shaft doesn't cause binding.... No need for the shaft hold down unless you upgrade the rockers...

[Mrbill426]

So no advantage at all over the stock steel hold downs other that being pretty??  See I have iron (273) rockers that I was going to use but I hear you have to have custom cut (length) push rods with those on a 340 rather than pre-cut bolt and go rockers. 
Years ago I had a 383 with Isky adjustable rockers and (I think) Sig Erson  ball & cup tubular push rods; still a Hyd (Crane) cam but it was all bolt and go, no problems.  I guess the 340 is a different animal in that respect.

Thanks

Purpose is to keep the shaft from distorting, If the shaft distorts the rocker bind... But the stamped steel rockers don't fit the shaft tightly so distorting the shaft doesn't cause binding.... No need for the shaft hold down unless you upgrade the rockers...

[Chryco Psycho]

If you are going to use the 273 bushed rockers then better shafts & hold downs can help .

[1 Wild R/T]

The 273 rockers are good.. Problem with the pushrods is because hydraulic lifters take a shorter pushrod than a solid cam... That's actually true with big blocks too... I have two sets of Isky rockers & a set of Crane rockers, all were used with hydraulic cams and mechanical length pushrods... All showed minor damage... I'm sure most guys get away with it, the Cranes I have I know the motor they came off of experienced two bent pushrods that were traced back to the rockers...

A couple years ago I got pushrods for a 340 with 273 rockers, those have been fine, I'l see if I can dig up the length....

We wound up at 7.150... FWIW Summit doesn't list a pre-made cup/ball pushrod at 7.150 so we ordered custom through Smith Bros...

[Mrbill426]

@Chryco Psycho no not at this point and they are not bushed... all iron; I was just thinking the hold downs might add some rigidity but maybe not worth it.  This project started out as a more performance build than it is now which going to a slightly warmed up stocker.  We decided to go more of a restoration with some pep.  Initial plans however resulted in a bunch beefed parts e.g. the rockers, hold downs, Edy heads, headers, multiple intakes (to choose), frame connectors, axle brace, multiple gear sets (to choose), stronger axle shafts, adj pinion snubber....

Anyway sounds like for my purpose the hold downs are overkill right now

Thanks!

If you are going to use the 273 bushed rockers then better shafts & hold downs can help .

[Mrbill426]

Thanks for the information.. I would still like to have that length if your find it.  Maybe I got lucky with that 383 then... it turned easily to 6K without skipping a beat.   Loved that engine!

The 273 rockers are good.. Problem with the pushrods is because hydraulic lifters take a shorter pushrod than a solid cam... That's actually true with big blocks too... I have two sets of Isky rockers & a set of Crane rockers, all were used with hydraulic cams and mechanical length pushrods... All showed minor damage... I'm sure most guys get away with it, the Cranes I have I know the motor they came off of experienced two bent pushrods that were traced back to the rockers...

A couple years ago I got pushrods for a 340 with 273 rockers, those have been fine, I'l see if I can dig up the length....

We wound up at 7.150... FWIW Summit doesn't list a pre-made cup/ball pushrod at 7.150 so we ordered custom through Smith Bros...