Ignition/detonation help please
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Postmaster
Joined: Oct 2005
Posts: 3,083
Likes: 4
From: Victoria , BC
Ok so I got a new remaned distributor today. As I mentioned before its a 73 f250 points 390 application distributor. I opened it up right away to see what I got. This bottom weights are different than my other distributor in motor. the slots are not like this in my other one.
I dont see any marks for the weight #'s ?
Do you guys think I should just swap over my petronix lll and run this setup? Think it will be an improvement or should i get it recurved at a shop for my setup??
The motor is in the truck in my avatar. 44" tires, 5:13 gears, 6200lbs give or take.
The springs in the new distributor are one light one heavier. Also when i suck on the vacuum advance before taking it apart i had to suck really hard but it did advance eventually..
I dont see any marks for the weight #'s ?
Do you guys think I should just swap over my petronix lll and run this setup? Think it will be an improvement or should i get it recurved at a shop for my setup??
The motor is in the truck in my avatar. 44" tires, 5:13 gears, 6200lbs give or take.
The springs in the new distributor are one light one heavier. Also when i suck on the vacuum advance before taking it apart i had to suck really hard but it did advance eventually..
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Postmaster
Joined: Oct 2005
Posts: 3,083
Likes: 4
From: Victoria , BC
pulled my distributor now and pulled apart. By spinning the shaft it advances about 3/4 way through the slot. It must be advancing way to fast as it has 2 light springs. The weight with slots is #rd 13L and 18. the slot is the 13 side
Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
So put a heavy spring on one side and you will be fixed. Then you can hook up the vacuum advance (the the ported vacuum nipple on the carb, please) and get a little better MPG with it.
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Postmaster
Joined: Oct 2005
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From: Victoria , BC
Yeah I just did that. I had a spring kit kicking around. I went from the one flimsy spring to a medium and the tension now acts like the new reman.
One thing I notice is when I hold bottom gear and spin shaft I get a little more advance turn out of my old distributor than the new one. I'm thinking I limit mine just a tad and I'll save the $100??
One thing I notice is when I hold bottom gear and spin shaft I get a little more advance turn out of my old distributor than the new one. I'm thinking I limit mine just a tad and I'll save the $100??
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Postmaster
Joined: Oct 2005
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From: Victoria , BC
Sound good?
Also does full advance hooked up to vacuum from timed port should i have it come in at 3500 rpm with a total around 38 to be ideal for my situation of a heavy truck?
Also does full advance hooked up to vacuum from timed port should i have it come in at 3500 rpm with a total around 38 to be ideal for my situation of a heavy truck?
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Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
Full mechanical advance has NOTHING to do with vacuum. The vacuum advance is a mileage improver and when you stomp the throttle it has no effect until you lift. If you have a light truck with at least a 3.91 rearend, then yeah, 38° at 3500 will work, but a heavy truck or with 3.50 gears is gonna need about 4000 to prevent pinging on the street. My '84 F250 Supercab/Superduty with a 460, C6 and 4.11 rear will not tolerate 38° at 3500 so I backed it off to 36° and it is happy. My old 1969 Torino Cobra with a 428CJ, C6 and 4.30 gears loved 38° at 2500 and would tolerate 44° in 1st and 2nd gear but had to be backed off to 38° for high gear. Did this using a neat trick with a dual point dist. and a switch on the shifter.
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Postmaster
Joined: Oct 2005
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From: Victoria , BC
Holy crap Bear significantly better! I took off the plastic boot limiter and wrapped it with some electrical tape to limit more. I put distributor back in and it had a minor hiccup when turning over. I retarded it a tiny till it turned over smooth and went for a drive. The roads are wet but it had a crisp clean snap off the line and I spun both 44's down the street!
I hit 3rd and pinging went to a very minimal. There was still some when on a slow coast and throttled hard in 3rd.
It had a bit of a high idle and when I shut it off it had a slight cough with some run on.
Now I can turn idle down to make that a littlebetter but it's almost there.
Should I advance or retard distributor now or is it limit more advance.
Thanks for help again it's almost perfect!
It even sounds nicer
I hit 3rd and pinging went to a very minimal. There was still some when on a slow coast and throttled hard in 3rd.
It had a bit of a high idle and when I shut it off it had a slight cough with some run on.
Now I can turn idle down to make that a littlebetter but it's almost there.
Should I advance or retard distributor now or is it limit more advance.
Thanks for help again it's almost perfect!
It even sounds nicer
Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
Back off the initial is the easiest. Or put a real fat bumper on the dist. timing stop. But be sure do the same to both stops.
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Postmaster
Joined: Oct 2005
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From: Victoria , BC
There is only one limiting post in this distributor. The 18L slot doesnt have one. Is this just so you can use the other slot if it was taken apart and be moved? anyways I just took about 2 "s of a 1/4" strip of some blue electrical tape and wrapped the limiter boot
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Postmaster
Joined: Oct 2005
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From: Victoria , BC
So I got a chance to go for a drive tonite on dry streets without spinning it like last nite.
Wow I think I gained at least 50 HP! The truck explodes off the line getting squirly in 2. I retarded the initial timing just a tad and the detonation is 95% gone. My only concern now is it still had some engine run on after I shut her off after the hard pulls.
Any other suggestions on this?
The motor sounds awesome though as it explodes off the line I'm pretty impressed!
Wow I think I gained at least 50 HP! The truck explodes off the line getting squirly in 2. I retarded the initial timing just a tad and the detonation is 95% gone. My only concern now is it still had some engine run on after I shut her off after the hard pulls.
Any other suggestions on this?
The motor sounds awesome though as it explodes off the line I'm pretty impressed!
Senior User
Joined: Oct 2004
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detonation
Without knowing the total specs of the engine; compression, heads and porting, intake, carb, exhaust; the cam specs are a waste of timing for dist. setup.
tater_51, the dist advance curve belong in a Mustang and not a truck unless you are running a minimum of 4.10 gears. Otherwise it is gonna ping the hell out of the motor.
tater_51, the dist advance curve belong in a Mustang and not a truck unless you are running a minimum of 4.10 gears. Otherwise it is gonna ping the hell out of the motor.