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  #16 (permalink)  
Old 09-08-2012, 05:47 PM
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Nope. Just plug and play. I don't know about anyone else, but i always put a drop of anti-seize on the threads when installing plugs. Makes them much easier to get out later on.

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  #17 (permalink)  
Old 09-08-2012, 06:42 PM
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Hi, I need some help with the timing, it is too high and I'm not sure why.

Before working on the vacuum advance setup I went and verified the total timing set last week and at 3000 rpm it was 36 degrees but when I went up to 4500 it went to 45 degrees! does that mean I didn't have it yet at 'all-in'? I used the MSD medium springs that are supposed to have all-in by 3000 rpm.
I don't recall how high we went last week but I do remember watching the timing and it stopped increasing between 3000 and 3500 so I assumed I was good.
Does timing increase again when you get into the high, close to WOT, range?

I then did an experiment and removed the springs in the distributor; the thought being that it will go 'all-in' to maximum timing at a lower RPM (4500 is awefully loud in a garage) and it immediately went to 55 degrees (at 1500 rpm), increasing to 2500 rpm still kept it at 55. That's crazy and does not make sense; the MSD 8362 is supposed to have a maximum mechanical advance of 21 degrees which should have made my total of 18 idle plus 21 be no more than 39 so where do the 55 come from.

I did ensure that the vacuum advance was closed off at the can and at the Carb so as not to affect this.

Any help is appreciated.
Gary

Ps. it idles at 18 degrees fine, no stumbling or anything. 18 is what it ended up with after my initial setting of 12 when we did our total timing setup last week and thought we had it at 36.
I confirmed my TDC at that time (using the piston stop tool method) to be correct and I have a timing tape installed on the balancer.

Last edited by ggevaert; 09-08-2012 at 06:48 PM.
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Old 09-08-2012, 07:20 PM
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Just read thread Ignition timing oddity on chassis dyno and what that person is experiencing is basically the same thing I am.

I will follow F-Bird'88's suggestions noted in that thread and put a mechanical limiter in place; looks like MSD does not sell anything like that so I will fabricate something and adjust until it stops at 36.

Gary
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Old 09-08-2012, 09:42 PM
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Its is easy to limit or lock out the mechanical advance travel on a HEi distributor.
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Old 09-09-2012, 12:06 AM
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Thanks F-Bird'88, I saw that picture lots of times and that's the one I will use as a guide. Seems odd that MSD does not yet make a kit to use for this but so be it.
Also, the other thread talks about the potential of having a bad distributor in this scenario; any thought on that. Why is the timing range so large ?? seems like it should have stopped at a number around the 40's....

I put a message into the MSD support forum asking them for input on what the total range is of their distributor.

Gary
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  #21 (permalink)  
Old 09-09-2012, 05:36 AM
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Mechanical Advance

Here is the instructions on the MSD 8362. Go to page 16 and read the instructions for locking out centrifugal advance. On page 17 it has info on limiting the vacuum advance. MSD IGNITION Wiring Diagrams and Tech Notes
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Old 09-09-2012, 12:39 PM
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Stop advance bushing

Ok Thanks cdminter59.
Looks like the MSD streetfire distributor I have (pn 8362) does not allow for the MSD advance stop bushing as it has no locknut/post on the bottom of the advance assembly as noted in the instructions you sent. I attached a pic showing where that post should have been.

I'll talk to MSD tommorow to confirm. I could go the way that F-Bird'88 indicated but I have a friend that has an application where he could use the distributor I have so I'm going to call my parts supplier to find out how much the MSD Pro-Billet 8365 is and I may go that direction. That unit will allow me to control both the mechanical advance with a stop and also has an adjustable vacuum advance (the stock 8362 does not).

Cheers
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Old 09-09-2012, 12:53 PM
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The MSD pro distributor will need custom modification to get the curve right too.
You are wasting your money. You cannot cure this by simply throwing money at it.
Fix the HEI style distributor you got.

The appropriately placed 10 cent machine screw must not stick up so far as to interfeer with the motion of the advance weights.
The diameter of the head of the machine screw sets the mech travel limit by creating a positive stop as apposed to depening on the weights and centerpiece to establish the stop limit of the mech advance system.
This allows you to get the generous 24+/- ish idle timing and 34-36 max advance timing.

Then:
The springs adjust the rate of mech advance within these points.
Very light tension springs or springs of the wrong free length create unstable, inconsistant advance at idle.

Last edited by F-BIRD'88; 09-09-2012 at 01:01 PM.
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Old 09-09-2012, 01:07 PM
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The advance bushings included with the MSD Pro billet distributor only allow a 18deg advance curve.

A special 10 and 14 limit bushing is available to cure this. It adds another $30 to the cost.
MSD does not sell this.

Fix what you got, for peanuts.

Crane and Mr gasket both offer and good replacement adjustable vac advance for HEI distributors.

The vac advance on your MSD HEI style distributor should be adjustable with a allen key. The allen key adjusts the spring rate
and rate of vac advance but not the vac adv stop limit.
It does not have a positive stop limit. You can fabricate this positive limit stop for the vac adv
for peanuts too.
But first verify the amount of vac advance travel and potential vac advance limit by testing with a hand vacuum pump
and timing light to see the limit you got at highest applyed vacuum. Should not be more than 15deg when highest vaccum is applied with the vacuum pump.
If it never gets beyond 12-15deg you are good to go.

The at rest point of the vac advance linkage arm also effects the distributor cap/rotor phasing alignment because it
moves the position of the mag pickup star ring. Poor cap/rotor phasing alignment causing all sorts of ignition issues like crossfire
cap arcing, detonation priignition , misfire, crossfire potential engine damage when out of wack.

This is how you blueprint a HEI disributor, reguardless of brand or price.

Last edited by F-BIRD'88; 09-09-2012 at 01:30 PM.
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Old 09-09-2012, 01:41 PM
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This is how you get the compete distributor curve dialed in to work with tight LSA cams EG" 106 LSA
like yours and the Comp "Thumpr Cams"
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Old 09-09-2012, 04:30 PM
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Mechanical Advance

Do you have a MSD box or just use the Streetfire as a stand alone distributor? If you had a box I would buy this Crane Distributor. http://www.cranecams.com/userfiles/file/408.pdf. I have two MSD Pro-Billet 85561. One brand new. The other has been rebuilt, new shaft, weights, springs, pick-up, Chevy style cap and rotor. I would sell both of mine to have that Crane.
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Old 09-09-2012, 08:00 PM
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Mechanical Advance

Hello,

F-Bird'88, you are correct, budgets must be maintained!! I'll look into contuing with my unit and using your your picture and notes to fabricate a stop.
Is there a particular machine screw size/type you go with that I could start with? Or am I looking at putting it in, testing, then shaving it down some, testing, shave some more, test, etc. etc.

The VAC advance on my unit is NOT adjustable. I guess it used to be (based on the 2 different user guides for 8362 I found out there) and when I called MSD they indicated that, Yes, they changed their street-fire "value brand" to no longer have an adjustable can but they do include the vacuum advance stop plate. (see attached picture).
The MSD tech also indicated that the vacuum advance can with this unit will go all the way up to 22 degrees advance. It kicks in at 5 hg and goes up linearly, based on Hg, to the max of 22 degrees. The stop plate willl stop it at that range listed for the letter selected.
When I pull the distributor out I will also be installing that stop plate and I am going to set it at the B (11-14 degrees stop) so as not to exceed 15.

Also, I read a bit up on Phasing alignment but did not think it would matter to me as I have a brand new distributor so everything should be smooth and work great. Is there some sort of test I can do to ensure there is no phasing problems?

cdminter59, no box, just the streetfire GM HEI with incorporated coil.

Cheers
Gary
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Last edited by ggevaert; 09-09-2012 at 08:08 PM.
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  #28 (permalink)  
Old 09-09-2012, 11:08 PM
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Modifed distributor cap to check phasing with a timing light.
The phasing moves with vac advance action.
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  #29 (permalink)  
Old 09-10-2012, 03:52 PM
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It is important to know how to do it yourself so you understand. F bird knows much and helps out with maximum verbosity. He deserves much thanks.

You can just throw money at it. For $70 4secondsflat.com will set up a distributor to any curve you want on the advance machine. Don, used to be very reasonable and fast return. Not to mention dead on accurate. Have not contacted them in over 10 years, but the site is still up.

There used to be tons of distributor shops that put the dizzy on the spin and suck machine. Now a days they are harder to find. Damn computers ruined everything except adult entertainment.
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Old 09-22-2012, 10:03 PM
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Almost there

Ok, Almost there but still an issue.

Installed the mechanical limiting screw in my MSD Streetfire pn 8362 and confirmed mechanical advance now limited at 36 degrees. Confirmed it by taking the springs out and going up to 4000 rpm. Stayed at 36 degrees all the way up there.

However, after that I tried a number of different advance rate springs out (2 blues, 1 heavy and 1 light, 2 silvers) and all of them cause the advance to stop at 32 degrees all the way to 4500 rpm. (did not go higher than that). What gives?

Idle timing continues to be set at 18 degrees. (vacuum advance disconnected and plugged)

Do I adjust the distributor to bring it to 36 degrees? Would that not raise the idle timing to above 20?

Since without the springs it goes to 36 and with it doesn't the problem has to be in the springs I think; I'm just not sure how to resolve this. I want 18 degrees of mechanical advance on top of my initial advance.

So, on my thought of this being springs related; I used the springs from the Pro-Billet advance kit (the store had that in stock and not the one for my distributor so I took it thinking springs are springs) so I'm thinking that maybe those springs are not designed to work with my distributor and cannot stretch far enough. The pro billet advance chart shows them going much higher than what I need but maybe that is specific to the pro-billet and, on my distributor, they can't stretch that far so are limited to 14 degrees?

thoughts?

Thanks
Gary

Last edited by ggevaert; 09-22-2012 at 10:14 PM.
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