Distributor changes

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Abodysrule

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OK, so I built my SL6 using another board's experts over the years, which included a special spring kit and limiting the mechanical advance and using a particular vacuum pod on the distributor. I don't recall all the specifics, but it was starting with a stock super six dizzy and for my mild build, the adjustments improved the performance markedly. NOTE: I'm no expert, but I can implement anything given clear instructions. For example, I welded/ground the centrifugal weight pin slots to limit the mechanical advance, installed the spring kit etc. on my super six distributor, all worked out great in that example. Again, I don't recall the specifics of that advance curve, mechanical, vacuum or total advance, but it was appropriate given the board experts guided me in that particular example.

So, now I'm preparing for a 360 magnum swap. The engine is being built, it'll have around 370 hp, run on pump gas, not sure of the cam specifics at this time, but it'll get dyno tested prior to shipment, and it will come with all those details. This will be a street machine, not racing it, but I do like quick response and a strong acceleration when I hit the pedal.

I have a stock mopar LA distributor for the engine already. Are there any modifications similar to those described above that I should consider for this 360 Magnum, or, should that be fine for this application generally speaking? Again, I realize there are many scenarios specific to any particular build or intended use.

Thanks for any insights all.

Brian
 
LOL there was just a similar thread. The basics:

1...ALL factory distributors for these are "smogger" distributors, with a long slow advance. Even 340 "performance" distributors in 68 were somewhat smogged as federally "that is when it started." And they got worse every year. ANYTHING 360 OEM is gonna be a "smogger." You can braze up and file the slots for advance limit, find some springs and modify the advance rate
2....Install a performance distributor, preferably with an adjustable advance system
3.....Buy the FBO limiter plate kit.
 
The advance curve you end up building will have a lot to with certain build parameters of the engine. What fuel its run on, what cylinder head is on it, type of piston, cylinder pressure, and camshaft profile. Wait until the engine is in the car and running and you have more build data and then tailor the curve to it.
 
OK, I checked my garage, I actually have a Mopar Performance Distributor, part number MOP440-430, from Mancini Racing (I have been planning for a small block mopar for over 2 years, so I forgot what I bought). Is that a "smogger" dizzy? Any links to springs or limiter plate kit mentioned above, specifics?
 
OK, so get the FBO distributor limiter and springs, maybe an adjustable vacuum can, then do some testing....
 
Is the factory vacuum canister adjustable or do I have to get one that is? I recall adjusting these with a small allen wrench through the vacuum hole....thoughts?
 
Abodysrule said:
OK, so get the FBO distributor limiter and springs, maybe an adjustable vacuum can, then do some testing....
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If that's how you want to go, yes. Just know this. My experience has been that those limiter plates aren't always accurate with their markings. In other words, a 14 degree slot for example, may go 16 or 18. That's been MY experience. That's why I prefer welding and filing the governor slots. It's a little more trouble, but not much. There's a chart floatin around here somewhere that equates how long the slots are to how many degrees of advance. Also, the "correct" way is to weld the outsides of the slots, since you're limiting how far the advance goes......although it works "either way".
 
Interesting, I did weld/file the slots on my slant six, it was pretty easy. I like the limiter plate idea as it is easier for testing different configurations. I could always use the plate for testing and once dialed in, weld the slots and ditch the plate.

What about my question on adjustable vacuum cans, any recommendations there?
 
Abodysrule said:
Interesting, I did weld/file the slots on my slant six, it was pretty easy. I like the limiter plate idea as it is easier for testing different configurations. I could always use the plate for testing and once dialed in, weld the slots and ditch the plate.

What about my question on adjustable vacuum cans, any recommendations there?
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I've never really shopped around much on those. I just pick one I think will get the job done and go. They don't work at all a high percentage of the time, since you're under load. Vacuum drops off then. All that's really important is that they do hold some advance at part throttle. Yeah, you can argue it, but I just don't get "that" specific about it. I do at least get an adjustable can though so I can tailor it a little. It's just not that critical. That's my opinion and I stick to it.
 
I just adjust the vac can as much as I can for the least advance. Then I adjust to what I want for max timing. Then check the base. If it’s where I want it I call it good. Then if u hook up the acc can u may get 3-5 degrees more at cruise. Kim
 
Lots of the time I use the light spring kit (P2932675). Sometimes just 1 light spring or sometimes both light springs. Different motors want different timing. Kim
 
OK, so the distributor I have does have the allen wrench adjustment inside the vacuum canister, does that mean I can use that canister, don't have to get another one? I can of course test it on the engine, see what advance I'm getting with it blocked off (mechanical) and with it hooked up to vacuum.
 
Post #4. Dist #440xxx.
I suspect that might be a 440 dist. It is close in length to the 360 dist, but turns in the opposite direction & is unusable in a SB.
Yes, very good idea to use an adjustable vac adv, so make sure the dist has one. 370 hp is going to need a reasonable size cam. So it will need a lot of initial [ idle timing ]. This is where the VA comes in [ pardon the pun ]. Connecting the VA to manifold vac allows timing to be added at idle. See bellow.

img268.jpg
 
The Mopar Performance distributor instruction sheet says for a small block with '89 or later cast iron heads (so my magnum I assume) it should have 32 BTDC mech and 18 vacuum for a total of 50 degrees (B/RB 56degrees, Hemi 53 degrees). Does that sound right?
 
...that seems really high to me, shouldn't it be like 30-32 degrees total ish...
 
Abodysrule said:
...that seems really high to me, shouldn't it be like 30-32 degrees total ish...
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yer confusing the word 'total' but don't feel bad because you're not the only one to use it that way.

Total mechanical timing is initial timing plus maximum mechanical advance.
Total timing while driving is mechanical timing at that rpm, plus vacuum advance.

Mopar Performance wanted to make one distributor work reasonably well for hot stock and mildly hot rodded engines.
So when following their instructions, set mechanical timing at 2800 rpm. For a magnum, that means 32* at 2800 rpm.
Idle timing will end up being whatever it ends up being. Measure it so you have a reference point. You MUST measure the rpm and write that down too.
(They didn't want to, or care to, explain how to tweak timing at idle. And most customers probably didn't want to go there. If you want to tweak it, we can come back to this.*)

Once mechanical timing is established, then take a drive with a vacuum gage attached so it can be seen from the inside. You or your passenger (or gopro) writes down the manifold vacuum while driving at steady highway speed (like 60 mph).
Then use that vacuum measurement so the total timing while cruising (about 2800 rpm) is 50*.
Say you measure 18 "Hg when cruising. There's already 32* mechanically at 2800 rpm. The vacuum advance needs to add 18* when 18"Hg are applied. That will equal 50*. A vacuum pump with gage is needed.
 
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RustyRatRod said:
Also, the "correct" way is to weld the outsides of the slots, since you're limiting how far the advance goes......although it works "either way".
Click to expand...
Kindof but no and yes.
Kindof because lots of folks thinkthe goal is to 'limit' the advance so in theory it seems right, but its not.
Sometimes it makes sense to limit the advance, but the way chrysler set up the distributors, many more times its better to weld the inside. That keeps the curve shaped properly for street driving, road racing, cricle track when using vacuum advance. Also helps a little bit on the top end with electronic ignition.
Abodysrule said:
Interesting, I did weld/file the slots on my slant six, it was pretty easy. I like the limiter plate idea as it is easier for testing different configurations. I could always use the plate for testing and once dialed in, weld the slots and ditch the plate.
Click to expand...
yes and no. If just working on limiting the advance (welding the outside) it will be close to the same. If dealing with a long quick initial advance, then the inside needs to be limited.
Presumbably the Mancini unit is set up the same as an original Chrysler Mopar Performance unit. Need to look inside and make some measurements to be sure. If it is, then advance is going to be pretty close out of the box.
Abodysrule said:
What about my question on adjustable vacuum cans, any recommendations there?
Click to expand...
It has one. You can adjust when the vacuum advance begins.
With some minor modifications, you can also limit the maxium degrees added. Its explained in the article I wrote.
 
Mattax said:
Kindof but no and yes.
Kindof because lots of folks thinkthe goal is to 'limit' the advance so in theory it seems right, but its not.
Sometimes it makes sense to limit the advance, but the way chrysler set up the distributors, many more times its better to weld the inside. That keeps the curve shaped properly for street driving, road racing, cricle track when using vacuum advance. Also helps a little bit on the top end with electronic ignition.

yes and no. If just working on limiting the advance (welding the outside) it will be close to the same. If dealing with a long quick initial advance, then the inside needs to be limited.
Presumbably the Mancini unit is set up the same as an original Chrysler Mopar Performance unit. Need to look inside and make some measurements to be sure. If it is, then advance is going to be pretty close out of the box.

It has one. You can adjust when the vacuum advance begins.
With some minor modifications, you can also limit the maxium degrees added. Its explained in the article I wrote.
Click to expand...
So Uncle Tony was wrong? Say it ain't so! lol
 
Mattax said:
:lol:

Technically, yea. Knowing how to be a successful writer and youtuber, apparently he's pretty good.
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I don't care who says what, he and Kathy are good people.
 
RustyRatRod said:
I don't care who says what, he and Kathy are good people.
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I'll take your word for that. Good people can be wrong sometimes. Sometimes bad people can be right. Heck its easy enough to be right or wrong and not know why - so we take a guess that seems reasonable.
 
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