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I have initial timing at 6 now. It was closer to 15 and would diesel terribly. Still deisels, but barely. Just filled the tank with 93 octane to see if that corrects it.
I pulled the thermostat but had issues getting the housing to seal without it in. Ultimately I decided to just go ahead and install a new thermostat, since I was back at the parts store for another gasket. I replaced the 195 with a 180 (I know that may start a debate, but I thought keeping the temp down a little isn't going to hurt) and went for a drive. The hood is still off and I only drove on a backroad where I could only keep a constant speed of around 60 mph for about 5 miles, as opposed the the previous conditions where I was on the interstate at 70 mph for 25 miles.
The temp stays on 180 degrees until I move the temp controls to "cool" and close the valve. At that point, the temp is climbing, but only to 220 degrees now. It is also climbing much slower. Where it was climbing in about 10 seconds, now it takes over a minute.
I also adjusted my timing, as I am having some Dieseling issues. I believe this was part of the reason I was running around 210 with a 195 thermostat.
So not ideal, but better. At this point I have to suspect my radiator is not flowing as well as it should. Before going any further with it, I want to get the hood installed to see if/how that impacts it. Maybe it will provide better airflow and drop the temp down closer to 200 degrees, where I would be more comfortable. I have a couple small adjustments to make before putting the hood on, so it may be a couple weeks before I can provide another update.
Another thought and detail: I only running water in the radiator at the moment; not antifreeze. I had an issue with the radiator neck that I had to have braised, which was causing it to leak previously. Now it is air tight and I need to put antifreeze in. I'm not sure if that will help drop the temp any or not.
Thanks again, everyone, for your help,
Keith
Antifreeze will actually make a cooling system run a tad hotter......
Retarding the timing like you did will increase coolant temps......you do not set timing at idle...you set it at or around 3000 rpm for a total number of 36 degrees with the vacuum advance unplugged.......timing makes zero difference in dieseling either, the ignition is not on when the car is shut off, in fact, grossly retarded timing like you have will cause dieseling to happen as you raise the temperature of the chamber a bunch.....you need the vacuum advance plgged in to full manifold vacuum at idle.
You might be on to something with the radiator having some blockage.........nothing else can really explain a 40 degree difference when the heater valve shuts........
At least you know the thermostat is not the cause.
Timing is something I seriously struggle with. The engine has less than 3K miles on it and Lars rebuilt the carb. I don't understand dieseling, but have read that timing could affect it.
I'll unplug the vacuum advance and set the timing to 36 degrees. Then I'll plug the vacuum into full manifold vacuum. Currently I'm ported on the carb.
I think I'll flush the radiator as well, to see if that helps any. I'm not sure if or how much that will help, but it won't hurt. Might waste some time and money, but at least I'll be able to say I tried.
You know @lars' email. Ask him for his timing papers, and follow them. Not to fault anyone, but anytime the abbreviated "yeah, I got it" summary is posted, inevitably something gets missed. You may need new dist springs, you may need to adjust you vac advance, etc.
Hopefully a radiator flush and a (proper) Lars-style tune fixes it.
I have the timing set properly and it's running good. No dieseling. I also have the hood on. I took it out for a drive yesterday and things look good. Temp outside was around 60 degrees. Drove in stop-and-go traffic with an average speed around 60. Engine temp never exceeded 160 degrees. Surprising how cool it was running. I think the hood has a lot to do with this. I also didn't see any changes in switching the flow valve off to the heater core.
I need to get out on the highway and really focus on this to make sure I'm good, but so far it's looking good. I'm just surprised that I'm not seeing any changes with the flow valve off, since it was a 40 degree increase before. Maybe some air bubbles or something else. Either way, I think I'm good at the moment and will try to get out on a long highway/freeway soon, where I can keep the RPMs up and constant while cycling the valve to see if it is causing temp change.
I have the timing set properly and it's running good. No dieseling. I also have the hood on. I took it out for a drive yesterday and things look good. Temp outside was around 60 degrees. Drove in stop-and-go traffic with an average speed around 60. Engine temp never exceeded 160 degrees. Surprising how cool it was running. I think the hood has a lot to do with this. I also didn't see any changes in switching the flow valve off to the heater core.
I need to get out on the highway and really focus on this to make sure I'm good, but so far it's looking good. I'm just surprised that I'm not seeing any changes with the flow valve off, since it was a 40 degree increase before. Maybe some air bubbles or something else. Either way, I think I'm good at the moment and will try to get out on a long highway/freeway soon, where I can keep the RPMs up and constant while cycling the valve to see if it is causing temp change.
Have a great holiday week,
Keith
So no other changes but timing correct? And it responded? Where do you have it now?
@Jebbysan Not since installing the new thermostat (180), aside from installing the hood. I have initial around 16, mechanical at 36 and vacuum advance connected to full vacuum.
I did give it one full WOT punch and had a little bog that I may need to adjust, but that was on my initial test drive. After that, I was more in cruising mode with moderate accelerations.
Looking forward to seeing photos, and seeing your temperature measurements confirmed with an IR gun or some other method.
Here's a run I did using an Arduino with 4 thermocouples. The "water temp" channel was taped to the outside of the upper radiator hose. Insulated, but still in the engine compartment, so that may account for some of the low temps. The rest could be from the tiny holes in the 180 degree thermostat. At any rate, my cooling fans (195/185) never came on during this run.
Last edited by Bikespace; Nov 20, 2023 at 11:53 AM.
@Jebbysan Not since installing the new thermostat (180), aside from installing the hood. I have initial around 16, mechanical at 36 and vacuum advance connected to full vacuum.
I did give it one full WOT punch and had a little bog that I may need to adjust, but that was on my initial test drive. After that, I was more in cruising mode with moderate accelerations.
Keith
That's great......and it is valuable info on how much timing affects coolant temps......
GM would not have had to perform any of the cooling tricks they had for C3's over the years had they been able to tune them correctly......and my 406 with a 100% stock cooling system (save for the stat) is a testament to that.....
