340 Static Compression Numbers and Test Procedure
Very roughly sketched on your graph are the timing curves you'd see for the DC/MP distributors if they were set up for approx 33* BTC at 4000 rpm.
Blue is the mechanical advance race unit. Black is the vacuum advance equiped unit. We can see your current timing might be in the ballpark if you were running vac advance. So that was reasonable when you were trying to set that up.
Notice the difference with the mechanical only distributor's advance. It can be very quick in. I wouldn't go quite that fast wiith the MSD, but it should be quicker.
As far as initial (base) timing with the DC distributors goes, they are too little for what you're doing.
The vac advance unit was for a milder engine, so 12* was tolerable.
On the race unit they didn't care so much about idle when these were made, but did want easy restarts. The penalty for easy restarts was the timing hunted up and down with rpm at race engine idle speeds. On an automatic especially, this will drive most people nuts except for racing. Been there done that.
But look where timing is at 800 to 1000 rpm.
Very roughly sketched on your graph are the timing curves you'd see for the DC/MP distributors if they were set up for approx 33* BTC at 4000 rpm.
Blue is the mechanical advance race unit. Black is the vacuum advance equiped unit. We can see your current timing might be in the ballpark if you were running vac advance. So that was reasonable when you were trying to set that up.
Notice the difference with the mechanical only distributor's advance. It can be very quick in. I wouldn't go quite that fast wiith the MSD, but it should be quicker.
As far as initial (base) timing with the DC distributors goes, they are too little for what you're doing.
The vac advance unit was for a milder engine, so 12* was tolerable.
On the race unit they didn't care so much about idle when these were made, but did want easy restarts. The penalty for easy restarts was the timing hunted up and down with rpm at race engine idle speeds. On an automatic especially, this will drive most people nuts except for racing. Been there done that.
But look where timing is at 800 to 1000 rpm.
