That would be the first thing I would fix! Remember that with vacuum advance, you might be running 50 degrees advance down the highway. If you are only at 20-25 degrees of timing, then you are essentially running (very inefficiently) at 25 degrees retarded! Bet your gas mileage gets better too. -Bob Cunningham
Okay, I guess I am putting the cart in front of the horse. I want to dial it in, but its running hot. Vacuum advance is connected to ported vacuum correct? So if base timing is set at 5* or 16* and the thing still runs hot AT IDLE where does vacuum advance come in? I am talking just sitting and running with out driving for 20 minutes. The thing heats up. Running 70MPH for 30 miles and the thing stays cool until stopped All with no vacuum advance. Diaphram is shot. Thanks for the replies John
John, When your out on the highway, all your mechanical advance is in, so your running at 32* Then when you idle it, your back to initial timing, and that is when it heats up. Replace the vacuum advance cannister, and run it to full manifold vacuum. That way, at idle you will have full vacuum advance. See if it still heats up at idle like that. Of course with a quick advance curve, a stock vacuum advance will give you too much advance at cruising speed, so you'll have to limit it to about 10 degrees. E-mail the ignitionman and ask him to send you the pictures and instructions on how to make a limiting plate for your vacuum advance. If you run full manifold vacuum and 16 initial, you'll be at 26* at idle, and when you floor it the vacuum will go away, and you'll have 32 total. Good luck.
Larry, Got to play with the car some. Distributor issues need to be corrected first. Just for grins I tried timing the car with a vacuum gauge. I could get about 18" of vacuum, but that put me at about 55*. Then backed it down to about 16" of vacuum and was still about 36*. Did not try driving the car. The best part is the car ran cool and the thermostat even closed while I was running the car. Hoping if I get my distributor dialed in I will be running cool. John:TU:
i had similar problems, and richening up the primary circuit definately helped things tremendously. every combo is different but running 75 jets and 45 rods seems to work for me. im still trying to locate a set of 46 rods to see what thatll do, but thats besides the point. Im definatly not saying to not have dave convert the dist. he did mine a few months ago, and the smoothness of the idle and increase in power are tremendous. That is on top of the noticable gains i recieved after playing with the timing curve myself. Car now runs at 180-190 all day, which is fine for me, and creeps up a little past 200 when shut off, but no more puking coolant.
Here is what I found to work on my car.... First off, lose the clutch fan altogether and get a good Hayden flex fan, The reasons being a noticeable increase in power and much more airflow with only a minor increase in noise. Second, If you think about it a 160 stat is next to useless because once it reaches 160 it never closes and therefore does not hold the coolant in the radiator long enough to cool it down, I found a 180 to be the only choice for the street. I was running a recored four row, a/c pulleys, Hayden flex fan and a shroud out of a '78 olds 88 and only had trouble when the outside temp was very high and then only at low speeds.
Saw a flex fan throw a blade and swore them off. There is no reason that the factory combo when set up properly will not keep the car running cool.
Well finally got to play with the Buick. Added a Dave Ray HEI. Running 14* initial. Running the vacuum advance off of manifold vacuum. Ran the car hard. No overheat issues. In fact it is running cool. The temps here in Phoenix have droped from mid 90s to mid 70s. I still believe this car is fixed by running more timing at idle. Lots more power, and it also seems to have fixed a vibration problem too. If you are looking for a fix for your 455 I would spend a lot of time on yor timing! John:beer
