Those of you running a manual transmission and a choke, what thermostatic coil are you using if you don't have the proper manual transmission thermostatic coil assembly? I have just gone through 8 month of troubleshooting poor performance following initial drive away after cold start. The problem was the manifold thermostatic coil. I have two 1970 Buick GS 455 with manual transmissions, both with the 7040243 carb and 1232269 thermostatic coil. When comparing the 1232269/manual and 1232261/automatic coils, I accidently installed the automatic coil onto the manual assembly, i.e. the original coil in my 1232269 assembly was replaced with the coil from my 1232261 assembly. The vehicle that I installed this mismatched coil on, one of my 1970 GS 455 manual cars, would start right up on cold start, go up onto fast idle, a tap of the accelerator pedal would lower the idle to the second step of the fast idle cam, and all seemed to be well. But when backing the vehicle out of the garage, it would flood and stall. Soot was evident from the tail pipes, and the plugs would cold foul. Eventually, after adjusting the primary and secondary choke pull-offs, I eliminated the stall but the vehicle would load up slightly on initial acceleration after cold start. This condition would clear quickly, by the time I got to the top of my street (about 1/8 mile), and then the car would operate normally. Letting the car idle and warm up for 5 minutes after cold start also worked to eliminate the load up. But none of my other GS cars (automatics) need such a long warm up, needing only a few seconds to be ready to drive away. So I just about got the auto coil to work with my manual transmission vehicle except for this initial load up. I had to open the choke valve beyond specs in order to get this far, but could never eliminate the initial stumble. Reinstalling the proper coil into the 1232269 assembly solved the problem. The bad news is that (1) I wasn't able to get the much more common 1232261 assembly to work perfectly, and (2) available replacement coils (as of December 2023 are still available from Greg Gessler's old company) won't work either. The 1232269 coil is very soft compared to 1232261. 1232269 depresses easily with light finger pressure, whereas 1232261 is much stiffer. Pictured below are the two 1232269 assemblies from my vehicles. Oddly, their coils are visibly different from one another, with different numbers of windings but both equally "soft". One of these coils has AG stamped on it, the other AN. The other coils that I tried are also pictured, but simply too "stiff" and kept the choke too closed for too long.
The original AC Delco springs (in the 1968-1970 time frame) have a two letter identifier stamped on the "hooked" end. Looking at the coils that I have I'm seeing the following: 1970 Buick 455 manual transmission 1232269: "AN" 1970 Buick 455 auto transmission 1232261: "AM" 1968-69 Buick 400 auto transmission 1384488:"AG" 1968-69 Buick 430 auto & manual transmission 1384487:"AF" Astute readers will note that above I say that the two 1232269 thermostatic coil assemblies had different coils, AN and AG. I feel fairly confident that the AN is original, but now I'm questioning if the AG is? The best news is that the AG coil is working as a substitute, and should be easier to find.
I'm amazed that there was such a big difference between the two & as as Jason said, suprised there was even a different one & as you said, that the spring tensiin would be that different.
Those of you reading this who live at altitudes closer to sea level may not experience this issue to the degree that I did. I just spoke with a fellow Rocky Mountain GS club member, who's been a professional mechanic all of his career, and his first car was (and is) a 4-speed GS 455 Buick. He said that at our altitude (we both live near Denver at 5300 feet) we can almost get away without a choke. He does say that his GS started and ran flawlessly with the original Quadrajet and choke assembly. Once he replaced these stock components with a Holly carburetor and aluminum intake, he didn't hook up a choke. Instead he just pumps the gas, turns the key, and feathers the throttle until the engine warms up. I too have experienced this recently, as last month I inherited a 1979 Mazda RX7. It wasn't until I had the vehicle back home in Denver did I actually try to start it, which it did without any issues. Only then did I realize it has a manual choke! He said that when working on customer cars years ago he routinely set the chokes up with minimal closing force, so that they would "come off the choke" as quickly as possible. He also said that our stock GM cars used a much better choke system than the other brands. Our Buicks can actually be set up to work well with the factory choke, whereas Chryslers and Fords from the same period were best handled by converting them to manual chokes. I too found this out to be true, as my ski car during the 1980s was a Mercury Monterey with the Ford 390 cid engine. After screwing around with the factory choke system for untold hours/days/months, I finally converted it to manual. My Buick Skylark with a Quadrajet became my ski car for one season, and the factory choke system worked flawlessly even at 60 degrees below zero. The original vinyl upholstery on the driver's seat cracked like glass at that temperature, but the choke worked!
Having lived @ sea level all my life I forget about issues w/altitude although I've done the no choke/pump/feather thing here too.
