Duraspark Timing
Thread Starter
|
New User
Joined: May 2005
Posts: 7
Likes: 0
Duraspark Timing
OK guys, here is my set up, 5.0 roller(306") Eddlebrock RPM Airgap, Holley Truck Avenger (670), longtube headers with Magnaflows and a Duraspark ignition.
This is in a 69 F100, approx 4200 lbs. It has a built C4.
If I set the timing for best performance (16 deg. at idle with ported vac plugged) it will not start when hot.
If I retard to where it starts fine it runs rough and is flat up to around 2500 rpm under acceleration.
I have the ignition retard wire on the starter solinoid.
Tried manifold vacuum, too much advance too late and unpredictable when the secondaries open, detonation.
I am thinking I need to either: recurve the distributor to advance sooner.
Or try manifold vacuum again but adjust the vac.advance at the canister
to limit total.
Anybody have experience with this?
Am I missing something?
Thanks for any input.
This is in a 69 F100, approx 4200 lbs. It has a built C4.
If I set the timing for best performance (16 deg. at idle with ported vac plugged) it will not start when hot.
If I retard to where it starts fine it runs rough and is flat up to around 2500 rpm under acceleration.
I have the ignition retard wire on the starter solinoid.
Tried manifold vacuum, too much advance too late and unpredictable when the secondaries open, detonation.
I am thinking I need to either: recurve the distributor to advance sooner.
Or try manifold vacuum again but adjust the vac.advance at the canister
to limit total.
Anybody have experience with this?
Am I missing something?
Thanks for any input.
Elder User
Joined: Jan 2004
Posts: 819
Likes: 0
From: Troy,NY
What kind of vacuum are you getting at idle? It could be a vacuum leak.
What's your total advance?
What cam are you running? Stock needs 302 firing order, HO uses 351 order.
Does it have a ballast resistor for the coil? Duraspark uses one or a resistor wire.
I'm leaning toward it being a vacuum leak.
That's too big a carb for what you have really. I run a 5.0 HO with y303 heads and an e cam. I'm using a 470 TA and it's plenty of carb for the motor. You should probably jet that sucker down a few.
What's your total advance?
What cam are you running? Stock needs 302 firing order, HO uses 351 order.
Does it have a ballast resistor for the coil? Duraspark uses one or a resistor wire.
I'm leaning toward it being a vacuum leak.
That's too big a carb for what you have really. I run a 5.0 HO with y303 heads and an e cam. I'm using a 470 TA and it's plenty of carb for the motor. You should probably jet that sucker down a few.
Thread Starter
|
New User
Joined: May 2005
Posts: 7
Likes: 0
Well, I figured out the problem.
After much interweb research and sore eyeballs, I decided to try a simple experiment first.
Ran a 5 dollar black double eyed battery ground strap from the lower starter bolt to the frame, readjusted the timing and went blazin around to get it good and hot.
Worked great. Apparantly not enough ground for starter to work properly.
I already had a strap from block to frame and the stock strap from manifold to the firewall.
While researching I also read about grounding the heads to the frame since the plugs ground to the heads.????
Something to think about.
After much interweb research and sore eyeballs, I decided to try a simple experiment first.
Ran a 5 dollar black double eyed battery ground strap from the lower starter bolt to the frame, readjusted the timing and went blazin around to get it good and hot.
Worked great. Apparantly not enough ground for starter to work properly.
I already had a strap from block to frame and the stock strap from manifold to the firewall.
While researching I also read about grounding the heads to the frame since the plugs ground to the heads.????
Something to think about.
