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I'm confused about the placement of the carburetor linkage return springs. 1967 with base motor 327/300 with M35 powerglide, stock 3810 carb. From the AIM, it looks like one of the two lime green springs hooks from the carb rearward to the breather pipe and the other lime green spring hooks from the trans linkage rearward to the left spark plug wire support. But is there a third spring (black?) that hooks from the carb forward to the bracket that picks up the first two left side intake manifold bolts? Did all base motors get the forward spring regardless of transmission? The AIM seems to say that all base motors got this manifold bracket, so it makes sense to me that the forward spring would be used. All of my parts catalogs seem to say that two lime green springs are required for base motor + powerglide, but whether a third spring forward is required is vague. Thanks in advance.
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My confusing opinion
On page 391 of Adams' book are two photos of an automatic equipped, 300 hp '67 engine. The photo on the left shows the forward bracket, but no forward carb spring. I think I can see the two springs to the rear. Based on the appearance of this engine, I believe these photos were from GM files.
On the next page are several photos of a different automatic car. These show the forward spring and only the outer (kick-down) rear spring. However, these photos look like they were taken much later than 1967.
My practical experience indicates that three springs are too many. The load of both a front and rear return spring as well as a kick-down rear spring give the accelerator pedal a very heavy feel.
I think that running just two rear springs is probably the factory design but a bad idea. This puts all of the force on the throttle shaft pulling in one direction. Over time, the carb baseplate will wear around the throttle shaft. This will cause a sticky throttle shaft and/or a vacuum leak.
I suggest using the one front return spring and just one rear spring for the kick-down.
By the way, paragon's reproduction rear springs are painted bright yellow. Should they be lime green? -
Re: My confusing opinion
Jerry,
Thanks for your reply. Page 152 of Dobbins fifth edition for C2 shows two photos, both with the front spring (with bracket) and one rear spring. The caption says the rear spring was lime green, but doesn't mention the color of the front spring. And from the pictures, the front spring has shorter legs than the rear spring. And you guessed it- I do have a sticky throttle, right off idle. When I release the gas pedal slowly, the throttle hangs up about 1200-1300 RPM and drops if I kick the pedal. This happened before I had the carb restored, and I thought that the throttle bores were worn so I had bushings installed and it still sticks. Before I complain to the restorer, I want to make sure that I am using the springs correctly. I can't remember where I purchased the springs, but it was probably Zip or CC, and they are of a light-greenish color. My judging manual 2nd edition page 130 says 'two lime green springs running to the engine vent tube', but I don't think this is correct-maybe a later edition says something else? So maybe all base engines received the front bracket regardless of transmission? Can any original owners shed some light? Thanks again.Comment
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