Trying to adjust valve lash and I ran into a problem. This is a 1962 235.
I found that the #4 exhaust valve adjustment screw is significantly deformed. I have attached a picture with both the intake and exhaust valve adjustment screws shown. (the exhaust on is on the top if it's not obvious )
Of course, I need to replace the messed up screw, but these are hard to find. I have heard that Mopar or Ford screws will work. I need more info. Can someone tell me what I need to say to the parts guy who wants to know make, model, year engine size?
The adjustment screws for Ford and Mopar are 7/16-20 thread, and there's usually a few on Ebay. I don't know if the pivot ball is exactly the same size, but even if there's a slight difference in the radius, new ones are bound to be better than badly worn older ones. Be sure to inspect your pushrod cups for cracks and/or wear. I'm tinkering with the idea of building high strength tubular pushrods from 3/8" seamless stainless steel tubing with balls on both ends, and using MOPAR adjusting screws with a cup shape instead of the original ball shape.
"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 Love your enemies and drive 'em nuts!
The ball is 11/32". I would try to obtain this radius, since a smaller one (5/16") will only make partial contact at the bottom of the pushrod cup. A larger one (3/8") will not fully enter the cup, the locus of contact will be a ring around the opening but nothing below that. Since the contact surfaces will be smaller in area than the originals, higher wear will result from both.
New information; upon closer inspection, I see that the push rod is very slightly bent just below the flared portion on the cup end. So, I need a new one of those too.
Thanks for the filling station tip. They want to charge me $15 + $45 shipping for one screw. They say that shipping is an estimate. They don't seem to carry the push rod. I'll give them a call.
So the ball diameter on the Ford screws are 3/8", Mopar ones are 5/16" and the original GM ones are 11/32".
Would a Ford or Mopar push rod (of the correct length, of course) be compatible with the GM lifter?
The Filling Station has always been reasonable on shipping charges. The only time I thought it was too high was when I was ordering a fan and something else that was long, which made the box real big. I contacted them and had them remove the fan, as I didn't need it right away. That one adjuster screw will probably cost you about $5 to ship. Definitely give them a call. Good outfit. They will many times call me to confirm on the orders I place with them. I think that's what they did with the fan shipment.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
The adjustment screws are absolutly miserable to locate. A couple of years ago when I was putting together one of my 261 motors, I used a set of chrome moly push rods that I had purchased from jack clifford like 30 years before and had never used. Installed them with a nos sealed power rocker set. I usually blue up the cup and ball and run the push rod cup and ball through a few cycles (by hand) just to confirm the ball is seated in the cup. For whatever reason I did not do it this time. About 5 months later, the motor started running really badly. When I pulled the rocker cover off, the cup had fractured, and the push rod on the exhaust side jammed in between the rocker. I pulled the entire assembly apart and ran the cups and adjusters. Yep, the cups were ever so slightly smaller then they should have been resulting in the ball essentially sitting on the rim of the push rod cup which then fractured from use.
I went a different route this time with push rods and contacted Smith Brothers Push Rods. They make high performance push rods for just about any motor, nothing smaller then 3/8 diameter though. They made me up a set of 3/8 chrome moly push rods with cups machined to fit precesily with their adjusters (which I think were an early Mopar Hemi ball adjuster) with a 12 point adjuster nut. Truth be told, they are the nicest push rods and adjusters I have ever installed on one of our beloved stovebolt motors. Not the cheapest alternative by any means but 6 years later (and I am kinda hard on my motors), not one single issue.
Not for everyone I know, but it is another alternative.
Those adjusting screws look exactly like the MOPAR items on Ebay. The same vendor has a similar set with female ends that would work with ball-end pushrods. I'm accumulating the parts to make my own tubular pushrods with 3/8" stainless steel seamless tubing and cutoff ends of MOPAR ball end pushrods pressed into both ends. Total cost for 12 pushrods should be less than $100.00. 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 Love your enemies and drive 'em nuts!
Thanks. The extra lift also enlarges the pushrod's path (all in the head?) into a "stadium" shape. I have a gut feeling that differences among the castings may locate the relief hole slightly, etc.
There is a vendor on Ebay who is selling newly manufactured adjusting screws for Buick inline engines. They look very similar to stovebolt adjusters. I might buy one adjuster to do comparison measurements to a stovebolt item. Single adjusters are about $5.00 each, or he also has them in sets of 16. If they will interchange, it would probably be possible to make a deal for sets of 12. 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 Love your enemies and drive 'em nuts!
Looks like the Buick screws are 3/8-24 thread.. https://www.ebay.com/itm/284437335499?nma=true&si=i42gaNjfs5oTpRibZ2XXxx6KZT8%253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557
I think screws for the MGB have the same ball size but are also 3/8-24
With the supply of adjusters as scarce as they seem to be, it would probably be worthwhile for somebody with a CNC lathe to program it to knock out a few hundred or more. My son-in-law used to sell tooling to several CNC shops in our area. Maybe he knows of a shop that would be interested in making a small run of them.
It might also be possible to put a 3/8-24 Helicoil into a stovebolt rocker arm. 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 Love your enemies and drive 'em nuts!
Panic, to respond somewhat to your questions regarding different heads, the 848 head that I was originally running developed a crack and had to be replaced this past year. I replaced it with another 848 head and so with two different heads, no interference. That being said, it looks like there is enough meat on the head and block to drill the push rod holes slightly larger, sort of like what is done to use 3/8 push rods on a 250 and 292 head except because of the ball and cup arrangement, the 235 and 261 motors would not need guide plates.
The MGB is old enough that the thread may be 3/8-26. That pitch is common to Brit vehicles 50 years ago.
I can't tell if the adjusters are hardened (I have some NOS) but that would be good practice. I mate mine to their PR with Clover 600 compound and mark them for assembly.
Warning: increased lash over time frequently means some VT part is eating itself.
Smith Brothers will make up adjusters but they appear to only make them in 5/32 radius, 3/16 radius, and 9/64 radius for the ball end, but do apparantly offer those sizes in a 3/8-24 thread.
There's also some hardened ball-end adjusters on Ebay with 12MM threads. Rethreading rocker arms might be a viable option if a modern adjuster with a suitable radius is available. 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 Love your enemies and drive 'em nuts!
Has anyone ever seen PR adjusters with offset balls? Triumph 650 speed equipment from the dark ages (by Webco?). The thread is stock, the ball diameter stock, but installed with the ball closer to the shaft. This effectively shortens the pushrod-side lever, and increases the rocker ratio. Downside: the ball must rotate a full turn during lash to work.
Could this be done with stovebolt adjusters? But for safety I would greatly increase the ball diameter (yes, new pushrods) so that the shared material is at least as large as stock. Increase the 3/8" ball to 5/8" (a 5/8" ball bearing? Very hard, exactly round, cheap), with the outer edge of the ball in stock position, offsets the center by 1/8". The new ratio looks like 1.625:1, or +10%. Makes that .400" lift .440".
Aren't stovebolt rocker arms already a 1.7:1 ratio, or maybe a little more? There's already a very close intake valve to piston clearance problem. When milling a low compression 235 head .090" to equal the 848 combustion chamber volume, the intake valves have to be recessed into the head the same distance to avoid piston/valve interference. 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 Love your enemies and drive 'em nuts!
Not sure if this applies to every year, but 1.477:1 appears in Chevrolet service literature. I would guess that, like all pallet rockers, the ratio varies slightly during its range of motion
I'm probably thinking of 250/292 rockers. They're 1.75:1 I believe. 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 Love your enemies and drive 'em nuts!
"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 Love your enemies and drive 'em nuts!
The 292 rockers are actually just a tad bit larger at 1.74 or 1.75, I forget which.
The 235 and 261, yes, I agree 1.4 is probably right as I seem to recall they are commonly described as being just under 1.5. There were a couple of companies back in the day that sold off set rockers for either the exhaust or intake, I forget now, B&B was one company, there were others. Over the years I have kept my eyes out for a set mainly just to have as I dont think I would actually use them.
A piece of 7/16" oil hardening drill rod 36" long costs $20.00. That's enough material to make a full set of adjusters for two engines with a little bit left over. The rest is all fairly simple machine work. 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 Love your enemies and drive 'em nuts!
Doesn't everybody? Mine's a 60 year old manual lathe - - - - -with a modern CNC machine that would be maybe a 15 minute run!
LOL! 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 Love your enemies and drive 'em nuts!
Not without compromising the hardness of the ball. It would have to be rehardened after the machining, and that would have to be done by some sort of grinding process, or annealing the ball before machining it to a different radius. 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 Love your enemies and drive 'em nuts!
Aftermarket rockers: Fenton claimed .065” increased lift from their intake rocker. Thomas made magnesium rockers. Gotha made rockers, but I’m not sure for which valve, the material, or the ratio. Barker (B & B Automotive; “B & B” is cast in) offered these in 1.7:1 ratio (allow for some poetic license, it’s probably slightly less), which would have required the adjuster to be re-located toward the shaft center by .180” to 1.195”. In my opinion the claimed “7-10 hp increase” is exaggerated, and only achieved when combined with certain other modifications.
It sounds like that ad copy was written by Clifford. They think the truth is made out of rubber, too! 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 Love your enemies and drive 'em nuts!
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