Do the Mopar Proformance distributor's come equipped with the light distributor springs? Just wondering cause I'm wanting to take some advance out of the dizzy so I can put more intitial in. Thanks Jeff
Mopar Proformance Distributor
- Thread starter jefflock
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M
mopar3762
Guest
yes they do jeff. and on the rich running thread explained correct procedures for setting for max performance,take care
dgc333
Well-Known Member
They come with two pink springs and set up for 24 degrees of mechanical timing. If you are going to run more initial than 10 degrees you need to subtract the initial from the total (34-36) and set the mechanical advance stops for the difference. Then you will need to install stiffer springs to have the timing all in at the same rpm.
I have mine set for 15 initial with 18 in the distributor (magnum heads require less total). I wound up using two orange springs (next to stiffest) to have the timing all in at 2500 rpm. Get it from MP or Summit under MAllory p/n 29014.
The tuning kit has charts of advance curves to help select the correct springs, stop spacers with an assortment of springs to get it set up right.
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mopar3762
Guest
your post makes no sense whatsoever jeff,the M.P. distributers do come with the fast curve built in,between 2000 and and 2500 rpm. why would the magnum heads require less mechanical advance? so ya run 15 in the distributor and 35 total meaning your running with vacuum advance 50 degrees total, wrong,jefflock just buy the M.P. distributor and refer to the rich carb thread for proper procedures.who cares what the initial is ? its all in the distributor and on a performance engine ita always total,never initial, you got bum info friend.
AdamR
Big Member
A closed chambered head doesnt need as much total timing as a open chamber head does.
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mopar3762
Guest
? the question was does the M.P> distributors come with the fast advance curve built in, and the answers yes. I run closed chamber heads on my dart and set total as initial means nothing to me .38 degrees full on by 1200 rpm,running 13.5 to 1 compression with a msd distributor and control box, so the 915s on a bigblock require less total than a 906? thats news to me.no, the engines quite easy to start also.
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mopar3762
Guest
I do disagree with you though adam on a performance related car.
AdamR
Big Member
I should probably have stated that a modern quench type combustion chamber will require less timing then an open chamber. Not sure how the 915s react to timing because I have never ran them.
Also, changing the springs will effect how fast the timing comes in, not how much timing the distributor has. To make a change to the initial timing you will need to close up the slots in the advance plate. The MP piece should have an adjustable plate on it, if not you will need to weld up the slots.
Also, changing the springs will effect how fast the timing comes in, not how much timing the distributor has. To make a change to the initial timing you will need to close up the slots in the advance plate. The MP piece should have an adjustable plate on it, if not you will need to weld up the slots.
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mopar3762
Guest
rich carb thread tells it like it is. I run a new closed chamber head on my 451 and its 38 total with full advance in by 1200 rpm, I say we stop making it hard for jefflock and take this to the carb running rich thread to agree on disagreeing. But, yes the M.P. kit xomes with the fast curve and refer to the rich carb thread for proper procedures on making it haul the mail jefflock,this thread is probably confusing you more than helping ,sorry
Burntorange70
Well-Known Member
You need to get the Mallory kit P/N 29014. It has springs to chang the curve and advance limit tabs so you can limit the advance in the distributor.
Is this kit for a Mallory distributor only or will it fit my Mopar distributor also?
Jeff
M
mopar3762
Guest
M.P. dist kit comes with the fast curve. 2000 to 2500 all in by 35 degrees for a small block by 2000rpm or a tad more, same as the bigblock 38 degrees all in by 2000 rpm.call jegs, 1-800 345-4545 for correct info.
dgc333
Well-Known Member
The MP distributor has an adjustable stop for the mechanical advance built into the distributor and comes with the two light springs (pink in color) installed. The stops are set for 24 degrees of advance in the distributor. With 24 degrees in the distributor and the light pink springs your timing will all be in around 1800 rpm give or take manufacturing tolerances.
If you are running open chamber sb heads you want 34-36 degrees of total mechanical timing to be more accurate than that you would need to tune on a dyno or make many runs at the track. Closed chamber heads like the magnum head requires less total mechanical because it more efficiently mixes the fuel and air and as such requires less timing to get the maximum cylinder pressure at approx. 20 degrees ATDC thats need for max power.
As you go larger in cam duration there is more over lap and at lower rpms this results in less efficient cylinder filling which requires more initial timing to have proper lead to achieve a complete burn. Unless you have adequate initial timing it is difficult to get the idle and transition circuits in the carb.
If your only goal is going down the strip you can get away with setting total mechanical to the recommended numbers and forget about initial (lots of folks just lock out the distributor and have no timing) but for a street car you are leaving a lot of driveability on the table.
The correct way to tune an engine that has been modified from stock and is going to be driven on the street is to;
1. Dial in the initial timing using max manifold vacuum as your guide.
2. Set the mechanical in the distributor to desired total (34-36) - initial.
3. Adjust the rate of mechanical with the springs. For a street car some where in the range of 2000-2500 rpm. The springs will need to be stiffer as you remove mechanical advance from the distributor. Remember the weights are going to move less and you are starting with a higher initial.
4. Now you adjust the vacuum advance if you are using one . Remember that vacuum advance only operates at light load cruising. Again this is a condition that the cylinders are not efficiently filling and extra timing is need for a complete burn. Initial + mechanical in the distributor + vacuum advance will generally be around 50-52 degrees but seldom do you ever get in a situation that you have all of it. The key here is as much as possible at cruising manifold vacuum that does not cause detonation or throttle tip in detonation.
5. Now that you have the timing dialed in you can start fine tuning on the carb. Don't forget the carb needs to be close enough for the engine to run during the timing adjustments.
If you are running open chamber sb heads you want 34-36 degrees of total mechanical timing to be more accurate than that you would need to tune on a dyno or make many runs at the track. Closed chamber heads like the magnum head requires less total mechanical because it more efficiently mixes the fuel and air and as such requires less timing to get the maximum cylinder pressure at approx. 20 degrees ATDC thats need for max power.
As you go larger in cam duration there is more over lap and at lower rpms this results in less efficient cylinder filling which requires more initial timing to have proper lead to achieve a complete burn. Unless you have adequate initial timing it is difficult to get the idle and transition circuits in the carb.
If your only goal is going down the strip you can get away with setting total mechanical to the recommended numbers and forget about initial (lots of folks just lock out the distributor and have no timing) but for a street car you are leaving a lot of driveability on the table.
The correct way to tune an engine that has been modified from stock and is going to be driven on the street is to;
1. Dial in the initial timing using max manifold vacuum as your guide.
2. Set the mechanical in the distributor to desired total (34-36) - initial.
3. Adjust the rate of mechanical with the springs. For a street car some where in the range of 2000-2500 rpm. The springs will need to be stiffer as you remove mechanical advance from the distributor. Remember the weights are going to move less and you are starting with a higher initial.
4. Now you adjust the vacuum advance if you are using one . Remember that vacuum advance only operates at light load cruising. Again this is a condition that the cylinders are not efficiently filling and extra timing is need for a complete burn. Initial + mechanical in the distributor + vacuum advance will generally be around 50-52 degrees but seldom do you ever get in a situation that you have all of it. The key here is as much as possible at cruising manifold vacuum that does not cause detonation or throttle tip in detonation.
5. Now that you have the timing dialed in you can start fine tuning on the carb. Don't forget the carb needs to be close enough for the engine to run during the timing adjustments.
NiceFishEh
Well-Known Member
Dave:
I tried timing my stock 340 using a vacuum guage and ended up with around 26* initial. It took it all, idle smooth and sounded real strong. Brought the idle down to 825 rpm. Took it out and tried it...as suspected...it pinged quite a bit.
I kept backing it off until the ping went away. It's around 23* initial now. No starting issues and no ping.
I find more and more articles about not to trust 38 year old balancers, and how marks can be way off.
340's are internally balanced. Do they have a rubber ring? I don't remember seeing any rubber...thought it was solid steel. If it is steel, it could not slip.
My dist was set up on a machine. It has 19* mechanical with 34* total at 3500 rpm.
These are just numbers, are they not?
Regardless of what the initial is, the 19* in the mechical portion does not change...it's all relative, right? This give me a total of 42*.
What I do like about using a vacuum guage, and since no two engines are the same, is it take a lot of things into consideration like engine wear, cam duration, carb setting etc....
Comments...
Dgc Thank You for that well thought out post with simple instructions to follow. A job well done. Thanks again.
NiceFishEh Thank You for posting your results using this procedure. I'm going to try it today. I'm sure my distributor will have too much mecanical advance in it all so. I haven't ordered the kit yet to allow me to change the springs and install stops.
There are a lot of good posts in this thread and I hope we have all learned a few things.
Jeff
NiceFishEh Thank You for posting your results using this procedure. I'm going to try it today. I'm sure my distributor will have too much mecanical advance in it all so. I haven't ordered the kit yet to allow me to change the springs and install stops.
There are a lot of good posts in this thread and I hope we have all learned a few things.
Jeff
In your previous post above you stated the MP distributor has an adjustable stop. Can You explain the procedure on this a little before I remove mine to try it??? I would appreciate it and I'm sure others will also.
Thaks Again Jeff
Thaks Again Jeff
dgc333
Well-Known Member
If you have 19 degrees in the distributor and the intial set at 23 then your total is 42 as you stated. Yes the factory balancer has a small layer of rubber between the inner hub and the outer ring, that is how it takes out harmonics. The external balanced engines will have a weight attached to the back side of the outer ring.
Yes they can slip, the only way to check if it has accurately is; Buy, borrow or steal a degree wheel and piston stop. Mount the degree wheel to the end of the crank, put the piston stop in #1 and mount a piece of wire to the block to use as a pointer on the degree wheel. Turn the engine over by hand until the piston contacts the stop and record the number of the degree wheel. Reverse the rotation by hand until the piston contacts the stop from the other direction. The mid point between the two numbers is TDC and the timing mark on the balancer should be lined up with that point on the degree wheel.
If your marks are accurate and are truely at 42 degrees total then you need to take some timing out of the distributor. If it's an MP use a 12 degree spacer (or if you don't have the kit use a protractor glued to an old rotor and a wire as a pointer on the housing, you will want 6 on the protractor, distributor runs at 1/2 the speed of the crank so the degrees in the distributor are measured at 1/2).
Also, you will need stiffer springs when you reduce the advance in the distributor if you want it to stay at 3500 rpm for being all in.
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