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
Getting silver solder to stick to stainless steel and cast iron at the same time is difficult, if not impossible. Brass would be much simpler to get a water-tight bond. Of course, green LocTite "stud and bearing mount" along with a snug press fit would probably work as well as silver solder, and be easier to apply. It's stable up to 500+ degrees F.- - -far hotter than a sleeve exposed to coolant would ever get. 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
Learned something on the interwebs last night. Ended up on the website of a custom rocker manufacturer specializing in shaft mounted rockers. You can order roller rockers in all kinds of lengths, ratios, and (L/R) offset.
I’m sure they cost a bloody fortune, but looked to me like a guy could build a custom Stovebolt rocker set if he wanted.
I'm getting pretty close to getting my 216 head assembled- - - -just a bit more fabrication involved. Fortunately, the only "custom" parts involved will be the mounting plates for the rocker studs, and special length pushrods. The roller rockers and studs will be off the shelf big block V8 high performance items. I might be able to modify regular stovebolt pushrods if I choose not to use the roller valve lifters on the bottom end. I've figured out how to make a 261/Corvette cam fit a 216 block by machining the bearing journals for the smaller 216 cam bearings. 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
W/r/t custom shaft-mount rockers It's not the machining, which is obvious - begin with an aluminum plate. The hard part: with no other information, what are the relationships between the stems and rocker construction? For those not familiar: no rocker arm is a "see-saw" with the ends horizontal and the fulcrum dividing the arm lengths to get the right ratio.
I got the rocker studs mounted to a junk 216 head today, and started doing some preliminary fitting of the rocker arm to valve geometry. I'll be using a lash cap to widen the footprint at the top of the valve stem, and an adjustable pushrod to determine the best angle of the rocker to the valve stem- - - - looking for a 90 degree angle between the rocker tip and the valve halfway up the cam lobe. Obviously, that will need to be finalized once a complete valve train is mocked up- - - -cam, engine block, cylinder head, head gasket, etc.
Pushrod angles will be somewhat of a sticking point, especially if the same setup is applied to a 1954-up 235 with a different water jacket. I'll cross that bridge once I have a running 216 and/or spray oiler 235 in operation and some dyno testing documented.
Pics: 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
Dang, Jerry! I sure am happy to see you actually getting into building one of your pipe dreams, given your seemingly endless calamities in recent times. Very good to see! I am inspired. Makes me realize that I do indeed have at least a few good years left ahead of me.
Like Clint Eastwood says- - - - -"Don't let the old man in!" I just wish someone a few years younger (or maybe a LOT younger) would show some interest in carrying on the tradition of trying to do the "impossible"! So far, no takers, including my son and grandson! 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
I wish you were my Granddad. I'd be at the shop every day.
Last edited by Otto Skorzeny; Sun Jan 22 2023 05:31 PM.
1939 Packard Standard Eight Coupe (The Phantom) 1950 Chevrolet 3100 (Ol' Roy) 1956 Cadillac Coupe de Ville (The Bismarck) 1966 Oldsmobile Toronado (The Purple Knif) 1966 Ford Mustang (Little Red) 1964 Ford Galaxie 500 coupe 1979 Ford F-100 1976 Ford F-150 (Big Red) 1995 Ford F-150 (Newt)
Like Clint Eastwood says- - - - -"Don't let the old man in!" I just wish someone a few years younger (or maybe a LOT younger) would show some interest in carrying on the tradition of trying to do the "impossible"! So far, no takers, including my son and grandson! Jerry
Don't sell yourself so short. I'm sure you have inspired many, many on this site over the years to try high end, hairy projects.
