After an eventful afternoon dealing with a truck that either wouldn’t stay running OR once running ran at wide open throttle, I started investigating. I found that the screws holding my carter YF throttle plate onto the (insert name of part that turns it) had come apart and the 2 screws had broke off.
Where do I find 2 screws that will fit? Do I need to be concerned that I might have metal in my engine? (I have both screws and it appears that the soft metal had bent?)
The page also shows the vendor offering a tap to use in cleaning up the threads in your throttle shaft if that is needed.
Your picture looks like the original screws were brass and yes, they probably got sucked into the engine, although they could be just resting in one of the intake runners??? No idea (without completely unbuttoning your engine) to know if they may have gotten stuck someplace "bad" and have or could cause damage.
They are however small enough that they could have been ingested and blown out without doing any damage too. If you're not hearing anything out of the ordinary, you may be fine.
Hope this helps.
Dan
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
Thanks guys! I have a buddy bringing an old Rochester b that is only parts over and I’m going to see if the bolts fit. If not, I will have to buy a couple.
I would never have thought that this was the actual problem, but it does make sense that there were times that it died when I tried to give it fuel and yesterday getting wide open throttle.
I’ve never even heard of this issue previously. How common is it?
It looks like someone may have tried to remove them and broke the heads off because he was unaware that they're peened over on the other end.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
Those screws are typically staked to keep them in place. Basically a chisel mark to expand the end of the screw that sticks thru the throttle shaft, making it more difficult to back out. But nowadays, some permanent threadlocker does the same job. Yours look like they sheared off for some reason. Maybe the last rebuilder of that carb overtightened them or they just got weak from age. Like Dan said, they may have gotten sucked into the engine, but probably got spit out thru the exhaust. Being made of brass is a plus as it's a soft metal and won't cause a lot of damage bouncing around in a cylinder.
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.
Thank you for your knowledge. I’m going to buy some and use thread locker. I considered taking some out of another carb, but if it is spread, it will probably cause damage to the screw.
I'm glad the throttle plate didn't get sucked into the engine! When you reinstall it, be aware that the holes in the plate are somewhat larger than the screws, so you can snug them slightly and tap the plate around to center it in the throttle base bore. Then do the final tightening with thread locker once you're sure the plate is centered, by removing one screw at a time and applying the locking liquid. 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!
(1) The Rochester screws are 6x32, the Carter YF screws are either 3x48 or 4x40 thread, probably 3x48. DO NOT THINK ABOUT USED SCREWS!
(2) Before you start drilling and tapping, at least read the following procedure, it will save you MUCH grief!
First, heat the throttle shaft in the area of the screw(2), and allow to cool. Next, use a centering device (a diamond burr works very well) to start a small hole in the center of the broken end of the screw. Use a number 50 drill (0.070) and drill a hole maybe half way through the screw. Now, use a DULL number 48 drill with a variable speed drill, and attempt to gouge the drill into the hole in the screw. Once stuck, continued drilling will cause the screw to screw out the bottom side; AND THE ORIGINAL THREADS IN THE THROTTLE SHAFT WILL BE INTACT!
Once you are ready to reassemble, a HALF DROP of blue Loctite on each screw will prevent them from backing out, DO NOT ATTEMPT TO PEEN THE SCREWS! Make sure you center the throttle plate in the bore.
EDIT: I posted before reading the entire thread. This issue is quite common when Dr. Goodpliers works on the carburetor, and does not remove the peening from the reverse side. I have had 4-barrels come in with 8 twisted off screws (practice makes perfect!) I suppose it is possible that one could break without help, but that would be quite rare. Not nearly so difficult to repair as one that comes in with a broken not-so-easy-out stuck in the screw!
Jon
Good carburetion is fuelish hot air The most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes! The Carburetor Shop
Thank you for your advice! I will not use old screws (already purchased new ones). I have everything prepped for reassembly once the screws arrive next week.
I greatly appreciate learning from people smarter than I am! I’m glad to say that I wasn’t the Dr. Goodpliers that put the screws in!
Jon, I attempted to call your shop, then saw you answered my message on here.
