Hey all, I have been tinkering with tuning my newly built motor and have a question or two. First off, for those who don't know me it's a 390 with a 428 crank and CJ cam, edelbrock RPM performer intake and edelbrock 750 manual choke carb. Standard transmission.
The builder said to set the initial timing to 10-12 degrees. I did this, adjusted the idle mixture screws, and then went to set the timing. (Dizzy vacuum disconnected and line plugged) If I turn the distributor clockwise the RPM goes up from 650 to 1000. However this causes the timing advance to go up to 30 plus degrees. I then back off the idle adjusting screw to put it back round 650, closer to where it should. But the timing is still pretty advanced I think around 20 degrees - I'll check again today to be sure.
If I'm looking at the motor from the drivers side the dizzy vacuum module is pointing to about 10 o'clock, I started at about 9 oclock.
I also tried setting it with a vacuum gauge. It more or less did the same thing. HOWEVER, as I pull the vacuum gauge out of the brake line the idle goes up. I thought it was supposed to drop or even die? When I plug it back into the brake booster the idle drops to the same as when it was plugged into the vacuum gauge. Does this make sense, am I missing something? I have no real experience setting timing other than my old motor so I'm not real sure what I should be seeing.
thx, Dave J
The builder said to set the initial timing to 10-12 degrees. I did this, adjusted the idle mixture screws, and then went to set the timing. (Dizzy vacuum disconnected and line plugged) If I turn the distributor clockwise the RPM goes up from 650 to 1000. However this causes the timing advance to go up to 30 plus degrees. I then back off the idle adjusting screw to put it back round 650, closer to where it should. But the timing is still pretty advanced I think around 20 degrees - I'll check again today to be sure.
If I'm looking at the motor from the drivers side the dizzy vacuum module is pointing to about 10 o'clock, I started at about 9 oclock.
I also tried setting it with a vacuum gauge. It more or less did the same thing. HOWEVER, as I pull the vacuum gauge out of the brake line the idle goes up. I thought it was supposed to drop or even die? When I plug it back into the brake booster the idle drops to the same as when it was plugged into the vacuum gauge. Does this make sense, am I missing something? I have no real experience setting timing other than my old motor so I'm not real sure what I should be seeing.
thx, Dave J
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