I've almost finished machining the support bars for the rocker arm studs I'm planning on using to position a set of big block Chevy V8 roller rockers on a stovebolt six cylinder head. The next step will be installing the rocker support studs in the right position so the roller tip on the rocker arm will be positioned correctly over the valve stem tip. I've made a fixture that plugs into the valve guide and has a hole for a transfer punch to mark the support bars the correct distance from the guide centerline. That will assure that the geometry on all the rocker arms will be the same. Then the height of the rocker assembly will be set by using an adjustable length pushrod so the rocker tip will be at a 90 degree angle to the valve stem with the valve halfway open. Once the pushrod length is determined, I'll order custom length pushrods with the right tips on both ends. At least one engine that's under construction now is also going to have roller valve lifters from a MOPAR 440.
This type of geometry exercise is done on racing engines all the time. Once I have a running prototype engine and some dyno figures, I'm going to approach a CNC machinist friend about making a small run of the support bars. Assuming the dyno tests are successful, running stud-mounted roller rockers might just solve the problem with the short supply of good condition used rocker arms and shafts for 216 through 261 stovebolt engines, and maybe decrease the running friction of the shaft-mounted rockers as well. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. Ernest Hemingway
Yes, the pushrod holes need to be slotted, and there will be somewhat of a pushrod tilt between the lifter and the short side of the rocker. No problem- - - -there's plenty of room, and there are no coolant passages in that area to be compromised. I'll be using the original rocker shaft connector oil tube to feed a drip tube with holes above each rocker pivot and a needle valve in the oil line to adjust the flow. On the later engines with the internal oil passages, it's a simple matter to tap into the oil gallery in the head for the same circuit. Just like with every similar "impossible" engine modification I've done it the past 60-something years, it's mostly a matter of "Measure twice- - - -cut once- - - - -screw it up and start over a time or two!" The naysayers can hide and watch. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. Ernest Hemingway
Yes, the pushrod holes need to be slotted, and there will be somewhat of a pushrod tilt between the lifter and the short side of the rocker. No problem- - - -there's plenty of room, and there are no coolant passages in that area to be compromised. Jerry
Good luck with that...there's 1/8" of wall between the pushrod hole and the water jacket.
The 216 head I'm working with currently doesn't have a water jacket impingement problem. Brass tubes pressed into an angled hole and silver soldered into place might be needed on a 235 or 261 head. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. Ernest Hemingway
