I hope then once I am past these issues with the distrib and getting correct timing set the stumbling and the like goes away.
So with the vac adv dead and the timing prob not right on the car how is it running decently and not overheating most of the time?
Vacuum advance is only one part of the system. Ignition timing requirements change depending on engine RPM, and engine load. At full throttle, Buick engines make best power at 30-34* timing. At light load, an engine can tolerate more advance, 40-45* or more sometimes. This results in better efficiency at steady state cruise speeds. As engine RPM goes up, the spark must occur earlier to allow time for the mix to burn and deliver it's power, pushing the piston down the bore. Without enough ignition advance, the burn occurs later, not pushing the piston down as efficiently as it could. Also, more heat enters the cooling system instead of doing more work in pushing the piston down, and exiting the cylinder as exhaust heat. There are 3 parts of ignition advance, initial advance, mechanical advance, and vacuum advance. All 3 contribute to the total advance at any specific engine RPM. The engineers design the advance mechanisms to deliver the optimal ignition advance at all RPM. Initial advance is the starting point, and can be adjusted by rotating the distributor in the timing cover. Mechanical advance adds ignition advance with increasing RPM using centrifugal force on weights and springs inside the rotating distributor. Vacuum advance adds advance with high vacuum. Vacuum advance is a load sensing device. At small throttle angles and light load, the engine develops high vacuum. At wide open throttle, engine vacuum approaches ZERO. The more load on the engine, the less vacuum. The vacuum advance canister has a spring that OPPOSES engine vacuum. For the canister to add advance, vacuum must OVERCOME the spring tension. Therefore, the vacuum advance canister adds advance at light load, and takes it away at high load and full throttle. Best performance also has to coexist with best emission requirements of the day. Best performance and efficiency and best emissions ignition advance require some compromises by car manufacturers. Being that our cars are now exempt from current emissions requirements, we can tune for best performance and not worry about emissions requirements. Your 1972 Buick 350 distributor had the following specifications, The above only applies if you have the original 1112109 distributor. It may not 48 years later. The initial advance is specified as 4*. At your typical cruise RPM, the mechanical advance would add another 14 -15*, and the vacuum advance would add another 18*. So the total would be 4 + 15 + 18 =37*. Without the vacuum advance, you are on the highway with 18-19*, not good for the best MPG, and more heat going into the cooling system. If you floored the gas, the vacuum advance would drop out, leaving you with initial + full mechanical, 4 + 16 = 20*. Note best WOT power comes at 30-34*. You have 20*. Now you are sitting at idle, you are idling at 4*. No mechanical advance, no vacuum advance (ported vacuum is non existent at idle). So the motor has 4* of advance, which is retarded timing. Too much heat goes into the cooling system, which is why it runs hotter than the thermostat rating. The cooling system can't remove the excessive amount of heat being transferred, so the temperature just keeps climbing. That is why I suggested that you move the vacuum advance to manifold vacuum. Manifold vacuum is available at closed throttle, UNLIKE ported vacuum. If your canister was working, it would have boosted your ignition timing at idle to over 20*. That would have cooled the engine down. I hope you understand what I just posted. It took me half an hour to write this. Not sure you will grasp this. How can your engine run decently despite all this? The short answer is, Ignorance is Bliss.
Well as you are well aware, this stuff sticks in my head like water on a waxed surface, NOT WELL. If you wanted, send me your mailing addy via PM so I can send you a GIFT card to your fav place. You have went WAY out of your way to teach me these things. Sooo when I gt my new distrib from TA installed I need intial timing set at about 10-12 degree and total at 34 to 36 at 2500 rpm? And put the vac advance back on the ported on the carb?
If you get the distributor I linked from TA, the mechanical advance is adjustable. We can cross that bridge when we get to it.
I plan to order the one you linked here on lunch in a little bit. They only have the RED capped ones right now.
I have my distrib and plug wires. On vaca currently so won't get to it for a week or so. The car current distrib was converted to electronic so it has a coil, flame thrower or some name that is in the car currently. What brand should I got with that looks factory but will do it with this new electronic distrib that will be put in.
Yea I see they sell what looks like what I have but I will call them Monday. Mine in the car now is a flame thrower unit but looks OLD.
New Distrib is in and the car is running better. Shop told me the carb needs redone pretty bad. They said the carb was running pretty lean, that and the timing issues were most likely my over heat issues as Larry has advised me here. I drove it today, pretty hot this after noon and it never went over 190. So need to get the carb sent out and restored.
Well I have driven the car a few times and she running cooler at times it never did , so things look good. Still have not done the HWY drive that was causing the overheating when I got it home and parked it. With the carb running so poorly I am afraid the thing will finally puke and I will have to tow it home. Now the CARB. It always ran a little rough, bog down, stall, stumble from a start when cold. When the dizzy was installed the shop said it was running lean and was able to clean that up some and got it running where it was pretty good off the line from a cold start, no more stalls and stumbles. I am still getting some rough running, mis like feeling as you sit at a light in gear or driving down the road. If I just sit and idle in park it runs smooth. Can the carb be that old and worn that it could run like there are spark issues?
When I was replacing plugs on my car I broke two trying to get the one in on the front pass side behind AC unit. So I ran out to finish the last two on that side. So I got more and just let my shop put them in since they had the car for the Dizzy install. I put all the plugs I put in at .35, the two they put in they said they put them to .30. Do I need to pull those two and reset them?
