340 mopar rocker arm/shaft strength

[rewguy]

If I were to have a hyd. roller 340 (410 ci stroker), built on a budget, would stock rocker arms be fine at 140/closed 365/open spring pressure? Camshaft 234/246 on a 110, .550/.550. Wont be turned more than 6000 rpm max. Likely will peak about 5200rpm, and shift no higher than 5500-5800 tops. If stock rockers wont work, what is adequate?

[superpursuit]

This all depends on what your stock arms are. If they are the stamped steel type then no. If they are the adjustable type that take a ball and cup pushrod, then yes. You did not state which type of stock rocker arms you had. I hope this helps.

[statsystems]

If I were to have a hyd. roller 340 (410 ci stroker), built on a budget, would stock rocker arms be fine at 140/closed 365/open spring pressure? Camshaft 234/246 on a 110, .550/.550. Wont be turned more than 6000 rpm max. Likely will peak about 5200rpm, and shift no higher than 5500-5800 tops. If stock rockers wont work, what is adequate?

I wouldn't do it. A set of 273 rockers is cheap. I wouldn't run stamped steel rockers on my lawn mower.

[SupStk]

Aftermarket rocker shafts are a must have. The stock shafts go eggshapped when torqued. Ever wonder why the stock rockers fit so loosely?

[pamotorman]

. I wouldn't run stamped steel rockers on my lawn mower.


my 18 hp B&S powered sears riding mower does have stamped steel rockers.

[Krooser]

My sbm dirt track motor has stock adjustable rockers on it... spring pressures are about 140/400 and they look good. I also have a set of T and D's that are brand new that the engines PO didn't feel the need to install as he didn't have any trouble with the stock ones.

[rewguy]

Where is a good place to buy the adjustable 273 stock style rocker arm? And it oils through the shaft the same way as the stamped 340 version does?

[cgarb]

Do Mopar rockers have factory spacers or do the rockers have springs and the nylon buttons that keep them spaced. My 350 Buick rockers were set up that way. I would Imagine the adjustable rockers with some solid spacers made up would work rather well.

[Mark O'Neal]

If I were to have a hyd. roller 340 (410 ci stroker), built on a budget, would stock rocker arms be fine at 140/closed 365/open spring pressure? Camshaft 234/246 on a 110, .550/.550. Wont be turned more than 6000 rpm max. Likely will peak about 5200rpm, and shift no higher than 5500-5800 tops. If stock rockers wont work, what is adequate?

I wouldn't do it. A set of 273 rockers is cheap. I wouldn't run stamped steel rockers on my lawn mower.

What kind lawn mower do you got!?!

[Mark O'Neal]

Where is a good place to buy the adjustable 273 stock style rocker arm? And it oils through the shaft the same way as the stamped 340 version does?

http://www.hughesengines.com/Index/prod ... rtid=26576

[Geoff2]

Factory rockers will fit loosely with aftermarket r/shafts, just as they do with factory shafts. Purposely designed that way to oil the rocker/shaft interface.

[blown265]

Do Mopar rockers have factory spacers or do the rockers have springs and the nylon buttons that keep them spaced. My 350 Buick rockers were set up that way. I would Imagine the adjustable rockers with some solid spacers made up would work rather well.

The factory 273 adjustables use spacers to separate the rockers. On a set employed recently, I used the Huges Engines Shim Kit # HUG1700 in addition to the spacers to align the rockers and take up the clearance. Worked perfectly, and runs relatively quiet (for a solid flat tappet)
Regards
Paul

[DaveMcLain]

Those stock Mopar shaft mount rockers are pretty darn foolproof if installed correctly and I think they will work just fine with those loads. I think that other areas of the valvetrain will cause more trouble than the rockers if you switch it to a hydraulic roller. The pushrod angle at the lifter will become even more severe and you'll probably have to do some work on the heads where the pushrod passes through.

[fdicrasto]

As already stated, hydraulic roller means wicked pushrod angle requiring a lot of work to clear heads in that area. Just be prepared ahead of time with mock up if you go in that direction.

[SupStk]

Factory rockers will fit loosely with aftermarket r/shafts, just as they do with factory shafts. Purposely designed that way to oil the rocker/shaft interface.

Yes they will because the aftermarket shafts are the same diameter. Got an education years back. Installed bushings in Isky rockers for a BBM. Using the stock shafts, the rockers locked up after torquing. Put in Comp 8620 shafts problem solved and they did not have to be sloppy loose.