I found curious puzzle about core support screws by looking at the 70 and 71 Assembly manuals and also looking through the new AMK Products catalog that people recommended on this board which is very good by the way. The question is that the manuals list two screw options for the core support in multiple locations. It lists #9422232 for Flint cars and #3960314 for GMAD. The problem is that according to AMK's listing for thes part numbers the Flint number is for a self tapping screw and the GMAD is for a finer thread machine screw? How can this be as I believe that most of the holes are pre-threaded. The #9422232 is the only screw listed in the radiator cover. Also what screw head markings are correct. Thanks in advance.
Hi Dave, I haven't got time to look at my manuals right now, but I'll throw my two cents in. I have restored severl cars and also takne many more apart. One thing I noticed is that some cars the screws are fine thread for the fender holes and other cars they are very course self tapping screws. Same with rad support to fenderwells. Never really paid much attention until its time to run them in as they will each screw up the other styles threads of course. I woldn't mess with trying to change them, the self tapping ones for sure if you try to use the other style you will have all kinds of issues and strip out holes etc. AMK sells hardware, they aren't the experts on our cars. You'll probably get better answers here. Kinda like the NPD heater core clmaps being totally wrong size (and good greif GM used the same size heater core fittings for decades!)or the year one data plate id and VIN numbers they screwed up a while back, people tend to take it as gospel, its not. later Tim
I'll lend you my 3/4 inch impact wrench whith the wing nut addapter . I also got some old school square screws if you are intrested :Smarty:
Generally--the screws on the top of the core support (ie--all the top plate screws) are self tapping/coarse thread. All the others are machine thread(including the core support to fender). You'll probably never get a consensus on the head marking as the factory probably didn't use any one marking consistently. PMing you this week on "some" chrome screws :Brow:
Hate to disagree with others here but I have taken apart and put together over 100 Skylarks. Buick used coarse thread screws for all body panels items except where the fender bolts to the top of the cowl (A-pillar, top of cowl, firewall) Olds Cutlass used fine thread machine screws with a narrow point. So, if you find a fine thread screw on the core support, fenderwell, rad cover, etc....someone cross-threaded it and it is incorrect.
Sorry, but I disagree. Fenders to rad support, wheehouses to rad support on my 72 are all fine thread, and they have never been re-tapped or run out. You can't run a fine thread screw into a coarse thread hole without some kind of damage, these were all clean and well cut, and I took the car apart myself. Wheelhouses to fender are self tapping thread. I think perhaps fine thread should be explained, I think most guys mean it to be not self tapping, and it is actually NC. later Tim
George, weren't the fenders where they meet the core support pre threaded for the finer screws? The assembly manual says self tapping for Flint and finer for GMAD plants? Like Vinny Barbarino use to say "I'm so confused" o No:
Welllllll, hmmmmmmmmmmmmmmm Tim, I have a KC GS455 conv I am building now. It has the SAE 70 core support in it now and all screws are coarse thread! I have a 70 GS Flint car and it has all coarse threads in the core support. Regarding the over 100 cars I have stripped and some rebuilt, NEVER EVER ran into a fine thread Buick. Some were full size models and 90% were Skylark/GS models. I even stripped some "MADE IN CANADA" cars and they were also coarse thread. The reason why I know this is because I have Oldsmobile Cutlass, Corvettes and friends have Pontiacs. Buick is the only one with coarse threads. Tim, surprised to hear of your car with fine threads. I will post a pic of an Olds fine thread body screw and the Buick coarse thread screw here in a few minutes. When can also ask Buick Apostle Duane what he knows about this issue. :TU:
My 71 had an NOS core support installed by previous owner and most screws were the fine. I got brave and tried a course in one of the holes and it holds tight! :TU:
George, You have to take something into consideration that you are forgetting, you live in Florida, so the Buicks you see down there are mostly Flint cars. Mark Reeves from Atlanta only sees Flint cars, and therefore only has Flint hardware. It's great for working on GSX's, because all his hardware is correct. Now if he ever gets a Fremont or Framingham car to restore then he is **** out of luck. You guys are looking at a plant thing. I would bet that the majority of the 70-72 Oldsmobiles George sees were built at GMAD plants, like my 70 442 that was built in Linden NJ and shipped to Atlanta when new. Come on guys, you are arguing about sheet metal screws, try looking at body bushing bolts, shock bolts, etc. they are all different between plants and are called out in the assembly manuals. Duane PS. From fixing right inner fenders I have seen both coarse and fine threads in the square nuts pressed into the parts. If a customer sends me his original part and needs to have one installed I simply put the same type nut back in and keep on going. PSS. And here is another thing to think about, If everyone here thinks that GM never changed suppliers or got in different parts batches/ or stopped the assembly lines when they ran out of a certain type of screw, then I have some swamp land to sell ya.
OK, you guys are mis reading what i posted. The "fine thread" is much finer than the self tapping, so people call if fine thread (although it is actually national course). I don't argue technicalities, it makes you a snob. Kinda like front quarters and rear fenders, you know that they mean. The NC screws are fine compared to the self tapping screws, so people call them fine. Works for me, I knew what you all meant. But yes, on my car all the screws are NC thread, the fenderwell to fenders are self tapping, and there are no NF threaded screws there. Sheesh. It comes back to the same thing, put back what was in there.You can tell by looking. No need to order from AMK anyway, most automotive stores will have both styles in stock and they probably get them from the same place as AMK. Or do what I did, have the originals beadblasted and recoated, then you have correct head markings too, with original screws (or bolts before someone brings that up!!) :laugh: Later Tim
Thanks for clearing that up Duane! Hmmm, did not know you owned property in FL.....where is your swamp land??????
We have a 69 Chevelle in the shop that we are restoring. 40K mile original one owner car. Fender to core support bolts are sheet metal on one fender and machine on the other. Looks like it got whatever happened to be in the air gun at the time.
