Customs Chevy Stovebolt Fenton Rockers

I have installed on my Chevy 235 with stock camshaft Fenton Hi-Lift Rocker Arms on the intake valves. They were a classic nos part at the time of install. I can’t find any info on them like ratio or even if the existed from the internet. I know they do because I have the box and it says Fenton on the castings. I was thinking of upgrading to a Delta Bulldog cam 254/264 camshaft and wondered if these could still be used. According to “California Bill’s Chevrolet and Buick Speed Manual 1954 Edition. Page 37 on the subject rocker arms. “Hi-lift rockers are available for Chevrolet and can be i stalled on a stock engine, or will provide aditional performance were a racing cam is installed”. So Im taking it that they can be tried out and as long as when everything is installed and the lash set. Most likely won’t see any issues while running. Any help would be appreciated.

 

Use the soft spring method to check the clearance between the valves and piston. Or assemble one cyl and place clay on the piston top rotate it a full cycle and measure the clay.

 

Thanks for the info. But I’am unfamiliar witht the soft spring method. Sounds like a good thing to know

 

For the most part these HiLift rocker arms like Barker, Thomas, Fenton etc. shorten up the push rod side of the rocker. The stock (pretty skinny) push rods would clear the holes in the head but were not good for any higher than stock RPM. Going to a 5/16" or 3/8" diameter push rod would cause interference so the hole toward the valve side would need to elongated.
This should be tested with the head on but not permanently. Once you see how much it needed it can actually be done with a round bastard file off the block by the typical backyard guy in the 50's. Of course a mill would be the best. You only a few thou clearance and don't want to go into the water jacket of the head. Someday I'm going to use one of the sets of Thomas Magnesium Rockers I have for GMC's

 

With light weight springs you can also do it by putting the piston up with the cam in the off fire or overlap position and just push down on the springs with your hand/finger. I always do it with no head gasket. Usually they are about .060" which is actually enough so anymore you are really safe especially on a non full race engine...