Definately going to try the retiming and vacuum advance switch bypass and then run the same route. Ambient temp will be the same all week so it will be a valid comparison. Would be very happy if that does the trick. Thanks to all for the suggestions and ideas. Jeff
Make sure you check the vacuum advance canister to verify that it even works. When you hook it to manifold vacuum, the engine idle should increase noticeably. You can check it with a timing light also.
Round II- I drove the exact same route this morning plus one mile without a/c. Swimwear mandatory, ambient temp 102 degrees. Operating temp of the engine hovered between 195 and 200, reaching 205 idling in the driveway waiting for the garage door to be opened. Upon shutoff rose to 225 degrees. So that's about a 35 degree difference with the a/c on at a typical Palm Springs summer temp. Next step will be to adjust timing per recommendation and bypass directly to manifold vacuum. Jeff
Isn't the A/C supposed to make the idle solenoid kick open and raise the idle to prevent excessive heat? If you're idle doesn't move up when your A/C is on than that could be an issue. Or maybe the compressor clutch is putting out too much resistance. Just seems like a drastic change in temps with the compressor engaged o No:
The 30-35 degrees seems like a big difference to me. I was expecting 10 to 15. We're going to retime tomorrow and bypass the TCS System. It will be interesting to see what that does for temp.
No, that is an anti dieseling solenoid. It does not raise the idle speed, at least not on any Buick I've seen. Remember that the A/C condenser sits right in front of the radiator. The condenser gets hot. Then there is the added load from the compressor.
http://www.buickperformance.com/ACIdleSolenoids.htm May only be on the '72 and up cars. The '71 version is different.
Day three. TCS bypassed, base timing reset to 10 degrees. Ambient temperature cooler- 96 degrees. Exact same 10.2 mile test route. A/C on but not max. Operating temperature 160 degrees. When shut off temp climbed to 170 degrees. Will repeat this afternoon at higher ambient but the car is substantially, hugely cooler. Jeff
You have to show me that in a 1971 Buick chassis manual. I could be wrong, but I don't see why Buick would only have it for one year.
The temperature will always climb after shut down. That is completely normal. Sounds like the higher timing should solve your problem though.
Just going off what the site said about 71 having a different version of the solenoid. I have no experience with the 70-71 motors to base anything on. I do know that the solenoid is present on the 72-73 455's with AC because I have one on my engine. Mine doesn't work at the moment though since the A/C wiring is shot, so I can't varify how much of a change in rpms or how quickly it should respond. The OP has a '72 455 so the drastic change in temps with the AC could be a sign that the solenoid is out of adjustment or actually failed. Agreed about the temp spike after shutdown. That's normal heat soak and the temp should go back to normal within a couple minutes of restarting.
I watch mine do it every time I shut it off. Comes right back down on restart, However I've never had it climb so high as to boil out of the radiator.
I'm aware of the temp spike being normal. It's in the OP and on each update I've tracked and posted the figures. The significance is it's only ten degrees and not the 20+ I was experiencing. Thanks to all for your excellent suggestions and valuable assistance. My inclination is that bypassing the TCS has solved the issue. Jeff
If the TCS has not solved your problem, may I suggest new fan clutch...I had an experience where I replaced everything including fan clutch...long story short...bad fan clutch brand (tried several "HD") compared performance with my dad's orignal stage 1 fan clutch (could hear and feel difference), returned the "HD" fan clutch and went with AC Delco at X2 the price. My problem was solved. good luck.
