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Tech Question
Bill Secules, Philadelphia PA, 1971 Plymouth Satellite Sebring Plus 383
Hi Rick, I'm a first time writer, long time reader! I have some questions about choke thermostats. I've never really seen their function explained, unless you've done it already when I was napping.
My '71 Satellite Sebring Plus came equipped with a 383 2 barrel, and I want to swap a more or less factory 4 barrel (Holley) on. I have the carb, manifold, gaskets, what I think will work for linkage, etc.- all gotten on the cheap, and I want to keep it that way, since I now have Triplets! I want to use a regular choke thermostat rather than go to an electric choke. They are no longer available as service replacements anywhere, and NOS pieces for the application (69-72 383-440 with Holley 4 bbl) have gotten very expensive. I'm not concerned about strict originality, I just want it to work the way it did when it was new.
If I got a less expensive 2 barrel, 6 barrel or Carter piece and modified the linkage to fit, would it function the way I need it to, or are all of these different applications really that specific in function (different springs, rates, etc.)? The Holley set-up seems like it has a shorter link than the Carter set-up, so it looks easy enough to do this on the surface (cut it & bend it to mate up to the Holley). I can't imagine that they differ so much except for the way that the link fits the carb, but I really just don't know for sure.
The car will be a 3-season occasional driver - no winter driving for the forseeable future. What do you think?
BTW- whatever happened to your '72 Road Runner project car?
Bill-
This could be expanded to at least 50 pages. So, brief facts will have to suffice. Here goes...
First: Quite a few of the thermostats are being re-pop'd, look around.
The basic principle: As the engine warms, and vaporization is easier / more complete, the choke opens, leaning the mixture. In warm weather, cold engine, the choke should just barely close fully, then adjust the diaphragm to immediately open the max that the engine can "take" as soon as it starts. Over-rich is really a major problem - fuel wash, carboning up, etc.
All thermostats from that era are very similar. Later ones used a thermal-switch activated electric assist, which assured that the choke would open quicker in warmer ambients; some were even 2-step. (Requires different manifold). Also the stainless cup style reacted more quickly.
Some had an adjustment which basically adjusted the spring tension. In the '50s / early '60s, you were even supposed to disassemble and change the setting summer/winter.
Electric-only chokes are lousy. Hand chokes, w/skilled driver -- the best.
You didn't ask, but, if it were mine, I'd sure use a late-'60s Carter AVS setup.
The '72 'Runner is complete and sees occasional street and show use. Still ice cold air, too (R12, nuke the gay unborn whales with CO2 and Freon).
Rick
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