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prestolite dist springs

old hatt

Contributing Member
Does anyone have a source for replacement dist springs for model ibm7004b model distributor. Not real happy with what they look like and not getting the response I should when doing Fast Jeff's distributor exercise.
 
Old Hat, it's none of my business how you approach this, but here's my take on this.

I've been playing around with flyweight springs, adjusting advance curves, and trying different automotive ignition curves since the 60's.
We have latitude with the auto engine.
We do not have this same latitude with the Marine gasser because of Marine load detonation potential.
The OEM has given us an ignition curve to use.
At any given moment, and when set correctly, we may be only a few degrees away from a range of ignition advance that might cause detonation.
The OEM specs keep us where we need to be as determined by the OEM flyweight spring values, flyweights, etc.

A change to flyweight springs that may allow an advance curve to come on too early, may put the engine close to detonation.
Example:
An advance that is too early by 2* at the distributor, is 4* too early at the crankshaft.
4* above a normal advance @ X,XXX RPM may cause destructive detonation.


Point being, use caution if you change flyweight springs!

If you have access to a shop who owns an old school distributor machine, have them run your ignition distributor on their machine to check and/or re-calibrate this curve and limit.
They will usually have an array of flyweight springs that allow for any adjustment.
The distributor is brought up to engine RPM as the advance is displayed right before your eyes.



If hell bent on doing this yourself, you can use your engine for your "distributor testing machine" by strobing the timing marks through the various
rpm range.
At minimum have your timing marks read up to 35* or so.
This way you can strobe the marks and watch the progressive advance in "real time" and in "real degrees" (no digitally advancing timing light is
needed)

Then jot down the corresponding numbers, plot this out in graph form and compare your curve to the OEM curve.

Make further adjustments if need be.

Your engine will love you! :)
 
Thanks Rick and Grease /M. All I wanted to do is replace the rusted springs with new OEM and not change any curve etc. Is that not possible? Thanks
 
Thanks Rick and Grease /M. All I wanted to do is replace the rusted springs with new OEM and not change any curve etc. Is that not possible? Thanks
I fully understand what you are wanting to do.
Perhaps you aren't understanding how critical Marine Engine ignition advance is....... or perhaps better said, how critical it is to avoid excessive advance!
No offense to you at all. I don't want to cause any issues here.
I just don't want to see you damage your engine from Ignition Induced Detonation caused by an overly aggressive spark lead!
Damage that could be caused by incorrect flyweight return springs.

Changing these is somewhat risky in several regards without the aid of a distributor machine, OR... without the knowledge for doing this On-Engine.
These may sound silly, but never say never:

Are they going to be exact replacement springs?
Did the worker put the correct springs in the correctly marked package?
Was this an automotive kit... or a Marine kit?
Did the worker know the difference?
Did the kid pulling the order grab the right kit?
Are the new springs of the same value as the OEM Marine springs?

As I suggested, make sure that your harmonic balancer is marked off.
Install the new springs, fire the engine up, strobe your timing marks.
Set BASE advance.
Increase RPM to 1k.... check progressive advance and make note.
Increase RPM to 1.5K.... check progressive advance and make note.
Increase RPM to 2k........ see above
Increase RPM to 2.5K...... see above
Increase RPM to 3k........ see above
Increase RPM to 3.2 or 3.5k.... etc.

Plot this out in graph form, compare to your OEM curve.

If it's correct, you win, and you've just renewed your flyweight springs!



.
 
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Many of our Marine mechanical advance curves will show Ignition Distributor Advance only, and will represent crankshaft angle!
This means that BASE advance is not represented in the vertical scale.
So BASE must be added to the vertical scale when attempting to calculate true linear advance.
RPM is usually shown in crankshaft RPM... although some have shown distributor RPM.
Crankshaft RPM and crankshaft angle is more useful, IMO.

Here's a real cheezy graph that I threw together.
The numbers are meaningless as I just picked them out of the air.
So understand that this is an example only.

Also, I could not create a scale where it flattened off showing the limit RPM. Typically, these lines would become flat at around 3.5K rpm as they carried
on towards the right side of the graph..... so it's not quite accurate in that regard.

The graph created by the red line shows an imaginary curve predicate by the OEM's choice in flyweight springs.
Let's assume that it's correct for engine XYZ.

The blue and green lines are alternate curves predicated by replacement flyweight springs that we'll assume are incorrect.
After all, that's what I'm trying to demonstrate here. :D


Let's say that the blue line represents springs that are too light.
At 3k rpm, the vertical scale reads 25* advance.
Add BASE of 10*, and that's 35* @ 3k rpm.
This brings the progressive advance on much earlier, and may cause damage in the form of detonation.


Let's say that the green line represents springs that are too heavy.
At 3k rpm, the vertical scale reads 15* advance.
Add BASE of 10*, and that's 25* @ 3k rpm.
This brings the progressive advance on much later... typically NOT causing any damage, but will certainly cause low performance.


Hope this makes sense!
 

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I have deliberately leaned towards the side of sounding and being extremely cautious with this. You may very well do just fine with changing these
springs out.
I'm simply pointing out what can happen if a minor error was to occur and was to go un-noticed.

Pre-Ignition and Detonation are two entirely different phenomena. Ignition induced Detonation is not always audible from within an enclosed marine engine bay, and it takes only seconds to burn the tops out of several pistons.
I'd sure hate to see that happen.

.
 
I cant answer all of ricks questions it is a mallory marine product and they are color coded, which IS fun!!I wrote a reply the other day about when i rebuilt my Electronic ignition dist. Take it apart and polish everything with a dremel wire wheel lube em up spin it on the drill in reverse with a piece of hose and a nail punch,start stop start stop....stuff like that...I do have a old points type dist. hmmm maybe we should have look sea.

The internet explorer 9 has been acting up and causing havoc
 
Greasemonkey, I didn't actually expect anyone to answer those questions..... they were fictional and more so intended to be rhetorical as to provoke thought.

I'm not following your Mallory comment. The OP apparently has a Prestolite.

As for Internet Explorer .... whoah, I too have been having trouble and I thought that I might have been the only one.
I fired an email to Andrew, and apparently it will be looked into.

Old Hat.... I hope that I haven't scared you off. You still there???? :)


.
 
Yep still here. Been at the boat taking advantage of this great weather we are having. Through a friend found someone with an old sun distmachine who is going to check them out. Seen detonation issues and I can live with them. Thanks for all your great help and advice.
 
Old Hat, Chrysler Marine Corp hasn't made it easy to find their curves in graph form.
I'm afraid that you're going to need to search for this so you can supply this guy with a Chrysler OEM curve. Doubt that he'll have a Marine specs
for this.


Grease, you've likely not been around nor operated a distributor machine.
Today these are considered old school and are all but obsolete with exception of a few shops who still value owning one. They do have their place, even today....... especially for what we're talking about here. In fact, I believe that you may be able to purchase a modern day version.

Sun, Allen, King are just a few names that the old duffers would be familiar with. Sun was very popular.

hubs1_3crop.jpg





sun_620_640.jpg



http://s3.racingjunk.com/ui/6/62/24620626-819-SUN-504-DISTRIBUTOR-MACHINE.jpg

http://image.chevyhiperformance.com/f/9588753+w750+st0/p177850_image_large.jpg

http://corvaircenter.com/phorum/file.php?1,file=56209,filename=Allen_Distributor_Machine.jpg

Most photos that you'll see will have an auto distributor set up, but the Marine can be set up just as easily.

The machine spins the distributor at half engine RPM. Instead of strobing #1 cylinder alone, it strobes all cylinders and displays the spark triggering events on the
wheel below.
RPM will be shown and can be calculated as crankshaft RPM, so the operator can watch the progressive advance and plot it out.
He'll make changes right then and there if he's not getting the correct advance curve or limit RPM.

He can even watch to see if each cylinder division is equal.

These old machines were designed for the mechanic contact type distributors.
Here's a video for you.... not sure whose video!
http://www.youtube.com/watch?v=VfKgP5SAFis

Here's a guy checking an HEI system and using a separate strobe light, since these aren't compatable with the HEI system.
http://www.streetfire.net/video/a-sun-distributor-machine_2312539.htm
 
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Rick, Your right about the specs. If you remember we went round and round about this on a previous thread I started. He's an old timer (Just a few more than me) who has lived this stuff his entire life. We"ll see how it goes..
 
Yes, I do remember that!
Did we/you end up finding a curve for the Chrysler 440 Marine Engine????

If I recall, in your other thread we discussed that several degrees (one direction or the other) can make the difference between good performance or NOT..... and/or the issue of bordering on the edge of detonation.
As long as he fully understands Marine load ignition induced detonation potential, you should be OK.

I just wish that I could offer this curve to you.
Chrysler mentions BASE or Initial advance, but nothing any further.

Sheesh..... how could you omit this critical information??? :mad:
What's a Certified Chrysler Marine repair shop to do when a distributor's advancing unit needs to be checked??? :mad:
 
Your last sentence made me think. There has got to be some old Chrysler marine dealer around who has an answer to that question. In the mean time I will share with him all the info that was shared on the other thread and look for a certified Chrysler marine dealer..
 
Your last sentence made me think. There has got to be some old Chrysler marine dealer around who has an answer to that question. In the mean time I will share with him all the info that was shared on the other thread and look for a certified Chrysler marine dealer..
Yes, I was refering to Chrysler.... how could Chrysler Marine NOT spec out the advance curve, or at mininum give a BASE advance number and a Total Advance # and RPM.
Tune-Ups are meaningless without this information.
Anyone can install a distributor, set BASE advance, and call it good.
What separates the pros from the non-pros, is looking past their nose, and seeing where the progressive advance is, and verifying that it is correct.

Someone out there must have a source for this.... and a Marine source, not an automotive source!


Grease... who is King and what are his qualifications? Just curious.

Edit:

Old Hat, another suggestion might be to contact Mallory.
Mallory offers a distributor for this engine.
In order to provide a distributor, they absolutely need to know the advance curve and limit RPM.

BTW, my system is fouled up. I've tried to shoot you a PM, and cannot.
Would you shoot me a PM with your email address please?

Rick
.
 
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"What separates the pros from the non-pros, is looking past their nose"

Rick, your supposed to nose this!!

Mr. King He'll tell you most distibutors should be "all in" by 3000 engine rpm

I guarauntee that fella,if you sent him an email, would know what marine chrylser points advance would be or should be

Ask him how much the fancy machine is

Grease like...
 
1... "What separates the pros from the non-pros, is looking past their nose"
Rick, your supposed to nose this!!

2... Mr. King He'll tell you most distibutors should be "all in" by 3000 engine rpm

3... I guarauntee that fella,if you sent him an email, would know what marine chrylser points advance would be or should be

1... Good one! :D
Grease 1
Rick 0


2... I doubt that.
I could show you several Volvo Penta engines that do not want to see Full In that early.


3... That would be excellent. Finally this 440 advance curve thing could be put to bed.

Barry, contacting King may be a good idea... certainly worth a shot.
I still think that contacting someone like Mallory would be a better place to begin.
Both got their foothold in automotive performance industry....., and both have products that found their way into the automotive performance industry.
King's machine works for either.... however, Mallory became obligate to build Marine specific distributors, with specific Marine advance curves.
Had Mallory not, his product would have caused Marine engine damage....... King's would not have.
Just my take.



Grease...., my Mr. King question was a joke. In my post #14 I mentioned Sun, Allen and King.
Most people who are familiar with these machines know the King name as well as Sun and Allen.
Nice machine, btw.
The King looks to be the nicest one made. I've only operated the Sun and Allen machines.

I'm rather surprised that when he touched and moved the upper reluctor unit, he did not suggest that this was a CCW rotation distributor.
Perhaps he spun it the wrong direction for the demonstration.
If so, understood.

He is spot on regarding the math, as these machines read distributor RPM... not crank RPM.
Crankshaft RPM is what OEM specs will reference. So you must be savvy with the math, or you can make a mistake.

At/near 14:15 into the video, he calls out 30* @ 3k RPM.
That 30* is minus BASE. So if you add a BASE of (let's say) 8*, that's a TA of 38* @ 3k RPM.
That's quite a bit of TA, unless this is for a high performance 6 cylinder automotive engine.

At/near 14:29 into the video, he suggests that the curve shown is rather late. It may be for auto, but certainly not for Marine.
So for any of you Marine guys looking at this video, it is great... lots to learn from it.
However, be very clear on several accounts:

1.... the specs shown for that particular distributor will NOT would work for a Marine engine.
2.... use only the OEM Marine advance curve and full-in limit RPM, and bring the distributor into specs with it.

.
 
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Nice to see one of those old fashioned distributor testers again! Gone the way of records, 8 tracks and cassettes.

Jeff
 
Gone the way of records, 8 tracks and cassettes.
You mean to tell me that 8 tracks are gone????

The machines are dang near all gone today, Jeff.
I know a man who frequents automotive swap meets, and he says that he sees these for sale once in a while.


That King unit sure looks sweet, doesn't it?
 
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Ive been in the garage building the first ever grease machine,basically its a metal circle with a hole cut out and i tape the spark plugs at 45 degree for my v8 of course,and use a variable drill and a tach to do the same thing hes doing

throw some 12v at it

Im close right???
 
Jeff, I too have a comment to make, but I just remembered that I have a roast in the oven...... be back in a few! :rolleyes:

Grease, we're just poke'n fun at ya.
I think that machines like these (to do the job fully and accurately), are not only built with complexity and accuracy in mind, but are built to handle the many tasks; Variable RPM, Reverse Direction capable, Dwell Test, full Spark Event Array pattern display, balanced to limit vibration, and so on.
Look at Mr. King's machine...... there's quite a bit to it.

.
 
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