Beemon Posted July 8, 2017 Share Posted July 8, 2017 Bet you thought it was the engine, right? Well, kinda... When I was cleaning out the vacuum passage for the choke, I broke the choke butterfly screw on reinstall. Is this a special screw or should I settle for self tapping machine screws? 1 Link to comment Share on other sites More sharing options...
Bloo Posted July 8, 2017 Share Posted July 8, 2017 Normally those are brass screws, smooshed on the opposite side so they cant come out. I don't think its special. Carbking would know. Link to comment Share on other sites More sharing options...
Beemon Posted July 8, 2017 Author Share Posted July 8, 2017 I filed off the back end, but I think it just didn't have much left in it when I tightened it down. It never went tight like the other one, it just kept spinning until the head came off. Link to comment Share on other sites More sharing options...
Bill Stoneberg Posted July 8, 2017 Share Posted July 8, 2017 I read the title and said to myself "That boy has no luck at all" Glad it is something minor. Its going to take some work to get that out and they are special screws. But I dont see why a regular screw and loctite wouldn't work. I am sure CarbKing will chime in here. 1 Link to comment Share on other sites More sharing options...
Bloo Posted July 8, 2017 Share Posted July 8, 2017 When you get the remainder out of there you can go to ace hardware and compare the threads to a standard brass screw. They will either be the right pitch or they wont. If theres something real special about them, then there's probably spares in any carter carb from the same period. Loctite is a good idea on any screw in a position that could fall in your engine. I use purple on little screws like this. It is usually unnecessary on carters because the screws are staked in place. Link to comment Share on other sites More sharing options...
Aaron65 Posted July 8, 2017 Share Posted July 8, 2017 (edited) Here's a selection of screws I found after a quick search...you may want to give them a call. http://www.carburetion.com/sitesearch.aspx?category=ScrewTC&Title=Screws for Throttle and Chokes OR, If you figure out the size, McMaster Carr ships really quickly... https://www.mcmaster.com/#standard-flat-head-screws/=18enn4a Edited July 8, 2017 by Aaron65 (see edit history) Link to comment Share on other sites More sharing options...
Beemon Posted July 8, 2017 Author Share Posted July 8, 2017 Thanks for the links, Aaron. Carbs Unlimited is 10 minutes from me, but they're closed on the weekend. I'll try my local hardware store first - they have a really huge selection of screws, including small brass ones for light fixtures and such. Link to comment Share on other sites More sharing options...
EmTee Posted July 8, 2017 Share Posted July 8, 2017 Whew -- you had me worried! 1 Link to comment Share on other sites More sharing options...
carbking Posted July 8, 2017 Share Posted July 8, 2017 Carter used both 3x48 and 4x40 for choke butterfly screws, but the odds are on 3x48. To get the old screw out, drill a small top through from the HEAD side. Then, using a dull drill bit, drill in from the head side. Generally, the dull bit will jam in the screw, and spin it out. Don't try to upset the screw as was done by the factory. One drop of BLUE Loctite on the screw threads (and yes, I have the factory tool, but still use the Loctite). Jon. 5 Link to comment Share on other sites More sharing options...
Guest Posted July 8, 2017 Share Posted July 8, 2017 Left hand drill bits are fantastic for this kind of job. Usually the piece spins out before the hole is completed. Link to comment Share on other sites More sharing options...
60FlatTop Posted July 8, 2017 Share Posted July 8, 2017 I almost forgot that 1947 Dodge sedan I had when I was 14. That's the one I leaned there are certain parts of a carburetor you don't mess with. You young 'uns are late starters these days. IF I had a throttle shaft worn enough to bush, taking it apart would be after I wrapped a wet cotton string around the shaft just to be sure. And it might stay there. If you are ever doing an air pressure test on a fire sprinkler system I can help with that, too. Bernie 1 Link to comment Share on other sites More sharing options...
NTX5467 Posted July 8, 2017 Share Posted July 8, 2017 I think the main difference in the "carb" screws and "hardware store" screws is the height of the head of the screw. The "carb" screw will have a flatter head for better air flow across it, compared to the high done of the hardware store screws. BUT until a better alternative can be obtained, the hardware screws can work good enough to not immobilize the car. PLUS the blue Loctite rather than the earlier "staking" operation. NTX5467 1 Link to comment Share on other sites More sharing options...
carbking Posted July 8, 2017 Share Posted July 8, 2017 (edited) 3 hours ago, Tinindian said: Left hand drill bits are fantastic for this kind of job. Usually the piece spins out before the hole is completed. I quite agree, and they make life easier because one can drill from the back side of the screw. The problem is, they are quite expensive, and most enthusiasts never invest in a complete set. And Murphy's law WILL apply (if you don't have a complete set, the one you are missing is the one you need)! Bad enough cost-wise just to purchase a QUALITY set of right hand thread bits. We have the normal "large" set (1-60, 1/64-1/2, and A-Z) plus the 61-80 plus "fill-in" sizes not contained in the other sets with fractional metric bits. Over 1K $$$$. To do the same with left-hand thread bits would really get wild. I do have a bunch of these as well, but nowhere near a complete set. For anyone doing a lot of carburetors, there is a company in Colorado (don't remember the name) that offers a set of "orifice" drills (the small size drill bits with each bit having a 1/4 inch hex brass "holder" about an inch in length). Since one should seldom use the really small drills with power, the holders eliminate the need for insertion of a bit into an hand-held pin-vise. Jon. Edited July 8, 2017 by carbking (see edit history) Link to comment Share on other sites More sharing options...
carbking Posted July 8, 2017 Share Posted July 8, 2017 43 minutes ago, NTX5467 said: I think the main difference in the "carb" screws and "hardware store" screws is the height of the head of the screw. The "carb" screw will have a flatter head for better air flow across it, compared to the high done of the hardware store screws. BUT until a better alternative can be obtained, the hardware screws can work good enough to not immobilize the car. PLUS the blue Loctite rather than the earlier "staking" operation. NTX5467 Carter used both slotted-round-head and slotted-pan-head screws for the choke butterflies. Other companies (Rochester for one) used oval-head screws for choke butterflies. And of course Marvel had to be unique and used a flat-head 4x36 thread. I don't even want to think about the cost of our screw inventory! Jon. 1 Link to comment Share on other sites More sharing options...
Guest Posted July 8, 2017 Share Posted July 8, 2017 1 hour ago, carbking said: I don't even want to think about the cost of our screw inventory! Jon, this reminds me of working in the parts department at a GM dealer in the early 60's. We had two parts bins 30"x72" with six shelves each that were for standard stock. Free to the shop as shop supplies. For years it was not physically counted but charged to inventory at $150.00. The business was sold and this time we had to count every nut, bolt and washer. The two bins held $3500.00 of standard stock. The parts manager said now he knew why the inventory never balanced. Link to comment Share on other sites More sharing options...
60FlatTop Posted July 8, 2017 Share Posted July 8, 2017 How my friends and I learned not to "monkey" was brass screws in a carburetor. 1 Link to comment Share on other sites More sharing options...
Bhigdog Posted July 8, 2017 Share Posted July 8, 2017 19 minutes ago, 60FlatTop said: How my friends and I learned not to "monkey" was brass screws in a carburetor. Yup. it's just a damn screw you will never remove again. Do whatever works to hold the thing together. Re-tap it, rivit it. solder it. sheet metal screw it. ........Bob Link to comment Share on other sites More sharing options...
Bloo Posted July 8, 2017 Share Posted July 8, 2017 Yeah, I never remove those screws unless I absolutely have to, no matter what Carter's documentation says. The first thing I would try to remove it: Grab it from the back side (if any is sticking through) and screw it on through the shaft. Link to comment Share on other sites More sharing options...
Ttotired Posted July 8, 2017 Share Posted July 8, 2017 Left hand bits wont work for this unless you drill from the back (staked) side because the screw had been staked. Drill from the head side, that way (as said above) it will hopefully catch and wind (tighten) itself out much the same as a left hand bit, but cheaper Link to comment Share on other sites More sharing options...
Beemon Posted July 9, 2017 Author Share Posted July 9, 2017 I found the right screws at the specialty section of the hardware store under "gun screws". They're steel, but long so I need to cut them down. Also I just discovered a novice mistake - I put the primary butterflies in backwards. No wonder the carb wouldn't idle below 450. Anyways, I got it out. I had to completely drill it out with a 1/16 bit then chase it with a 5/64 bit to get it to unthread. Looking forward to these steel screws. Link to comment Share on other sites More sharing options...
Beemon Posted July 9, 2017 Author Share Posted July 9, 2017 So I learned something today about the WCFB. Number casting goes towards the center on the butterflies, opposite of Rochester. The new choke screw heads are smaller than the old ones, but are also the same height. I think I cut the screws because they are sticking out just a bit from the shaft. And of course, held in with Loctite Blue, just like everything else. Thanks for the thread specs, Jon! PS, the drilled hole in the choke butterfly, is that normal? I also noticed my accelerator rod is not like other WCFBs, where its L shaped at the pump (mine is straight). The pump sits level under the dust cover, so I'm not too worried about it. Link to comment Share on other sites More sharing options...
carbking Posted July 9, 2017 Share Posted July 9, 2017 (edited) Ben - the hole in the choke plate should be there. It is an inexpensive "relief valve" (if you look at lots of carburetors, you will see many with a spring-loaded relief valve on the choke plate). The relief valve is present to prevent an overrich mixture on full choke. Here is a Stromberg version currently on ebay - 192119928665. Carter also in earlier years on single barrel carbs, had a hokey 2 piece choke valve that was spring loaded. This type valve is quite common on tractor carbs (especially Marvel Schebler) and the spring is the first failure item on the carb. The throttle operating rod is not correct (as you guessed). The throttle operating rod for the 1956 Buick carb is unique to that carb because of the Buick throttle linkage. I don't have a single one in my inventory, but the print clearly shows a 90 degree on one end and a 135 degree on the other. If what you have can be adjusted so the pump operates correctly, I wouldn't lose sleep over it being the incorrect shape. And you are correct on the throttle plate numbers on Carter 4-barrel carbs. They are visible from the bottom and are toward the center of the carb. This pattern holds true for WCFB, AFB, AVS, and TQ. Carter did some things to make life easier for the rebuilder. Jon. Edited July 9, 2017 by carbking (see edit history) 1 Link to comment Share on other sites More sharing options...
Beemon Posted July 9, 2017 Author Share Posted July 9, 2017 Thanks for the clarifications! Yes the accelerator pump works fine as it sits. The pump arm under the dust cap sits level just like it explains in the shop manual and makes the pump travel the full shot at WOT. If it's not native to Buick, then I wonder where the pump rod came from because the surface is machined so the pump bracket can only go on one way. Link to comment Share on other sites More sharing options...
Frank DuVal Posted July 11, 2017 Share Posted July 11, 2017 One. Harbor freight left handed drill bits actually work buy the set, cheap! When they wear out, you can always buy another set. I own Hanson, Snap-on and HF. I now go for the HF first Two. Never ever use a steel sheet metal screw for a plate in the carburetor. When it loosens, and it will as the threads are few and tapered in such a short length. It falls into the engine! I was lucky, it happened on a Corvair Spyder I bought. Lucky the screw kept bouncing between the throttle plate and turbine fins. When the turbin find finally stopped turning, no boost, I investigated. Well at least I didn't put the screw into the head! Link to comment Share on other sites More sharing options...
Beemon Posted July 12, 2017 Author Share Posted July 12, 2017 I didn't use sheet metal screws on the plate. It was the same threads as the brass screws and I set them with loctite blue. I don't see why it would be any different between brass and steel if they're set the same way. Link to comment Share on other sites More sharing options...
KongaMan Posted July 12, 2017 Share Posted July 12, 2017 On 7/8/2017 at 9:28 AM, NTX5467 said: I think the main difference in the "carb" screws and "hardware store" screws is the height of the head of the screw. The "carb" screw will have a flatter head for better air flow across it, compared to the high done of the hardware store screws. BUT until a better alternative can be obtained, the hardware screws can work good enough to not immobilize the car. That's a simple fix: chuck the screw in a drill, turn on the drill, then shove the screw head into a piece of sandpaper (or a belt sander if you've got one). It works quite well to change the profile of a screw head. Link to comment Share on other sites More sharing options...
60FlatTop Posted July 12, 2017 Share Posted July 12, 2017 There's a T shirt. I found it using Ebay parts compatibility. Bernie 2 Link to comment Share on other sites More sharing options...
MrEarl Posted July 13, 2017 Share Posted July 13, 2017 What's Dallas Fort Worth got to do with it. Never mind answering...please! 1 Link to comment Share on other sites More sharing options...
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