Interesting quote from Ohio Tom, Distributor Mod.

[raygreenwood]

[beetlenut]

[spencerfvee]

[Don Jones]

I PM'd Ohio Tom today for clarification on the distributor mod. Here's his quote. I asked about Mark's use of weaker springs as i thought they would only do the advance faster and not limit it.

"Yes, weaker springs will just bring the advance in sooner. Gotta be careful with that as you don't want advance happening around idle rpms (500-1500rpm). You definitely want a stable timing at idle rpms.

Yes, I bend the limiter tabs inward a few degrees (from this: |_|, to look like /_\). I do them both equally.

I then use a tool to move/test each weight out to ensure that the bend has actually changed where the weight stops. A little bend won't do anything, then a little more starts having an effect. So bend, test, bend test....

Yes, I usually just lift the points plate out and then you can see everything.
I don't even remove the distributor from the motor. I just do it where it sets.

No ideas on making it easier. I can usually get it right on the first try.
I have been successful at popping that little metal cap out the side and reaching in with a screw driver, but it's far less scientific that way. Hard to see what you are doing."

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I did both of my distributors today. My "in car" Bosch 009 which was the hardest to do as i had to figure out how to get the points mounting plate out. This distributor has the 3 dimples (mounting locking). Looked thru other topics and found one from Glen and he shows how you have to rotate the mounting plate to the right by approx 1/2". I bent both advance limiting post to about 30 degrees towards the weight. Set the distributor back in the engine and set to 12 degrees static, ran engine and got 28 degrees total.

I bought a backup chinese 009 from CIP1 and installed a petronix I in it. This distributor looks better made than the bosch (appearance wise) and was easier to make the mod. Just remove 2 screws that hold the mounting plate and you're looking at the advance limiting posts. Same thing, bent the limiting post toward the weights about 30 degrees. Put it in and set it to 12 degrees static, fired the engine and checked with timing light and it max's at 30 degrees.

Tomorrow i will run the car for the 1st time, been a complete body off chassis restore that took 16 months of my retired limited life to accomplish.

- Mahalo Ohio Tom and Glenn -

[raygreenwood]

One other reason I am glad for this thread.....why I think a good rational discussion on this subject has been needed:

Again.....quick note .....that there are many applications from bone stock, to bone stock with emissions (which can limit you in this respect) to anything goes......

So.....for what must be decades I have been ranting against the mentality....the method....the idea.....that has been passed around as gospel ......"that one should set their upper end advance limit.....and let the timing at idle fall to where it wants to"

And millions have gotten away with it....and yet millions more have had crappy off the line performance and poor starting because of it.

And yet you wont even find this method in any of the factory manuals......or even in the Clymer, Haynes, Drake....or any other manual. Not even in John Muirs book......its not even a bone stock method.

As far as I can tell......its simply done because the books do not mention anything at all about idle timing unless your year and engine are slated to have their timing set at idle.

For those who do not know what I am ranting about.....the vast majority of type 4 engines (if not all of them).....eapecially those with stock injection....and yes they are pretty much in the "emissions era".....mostly list setting timing by removing the vacuum advance hoses and running the engine at 3500 rpm and turning the distributor body until 27° BTDC is achieved.......or a similar variation.

The purpose is to make sure that you are timed so that 100% of the mechanical advance is in when average cruise rpm is reached.
As noted.....when the engine family I primarily work with.....hae a perfectly functioning stock distributor (meaning not beat up, tweaked or worn out).....this gives between 5° and 8° at idle speed.

But far too many engines especially with age.....do not give a stable idle timing setting. And since the books do not state an idle timing range for most of these engines......it has somehow been morphed into the thought that its not important......hence....."let the idle timing fall where it may".

This has worked its way across the board to almost every type of stockish or even some mild builds ....where the owner is trying to address pinging and/or excessive advance.....or set timing with a different cam......he gets told....."rev it up until it stops advancing....set it at X° and let the idle fall where it wants to" ......and then they wonder why idle and starting sucks.

I have been ranting against this practice for decades. Ray

[oprn]

But Ray, nobody drives these cars that way. It's flat out or nothing... as soon as it starts the loud peddle goes to it's resting place... on the firewall!

Just kidding...

Actually though the more I see and read of the state of art of these cars today and the parts we get now... daily drivability is not very high on the radar. It's all about top end.
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We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age)

[raygreenwood]

[FreeBug]

I know that this isn't at all the subject, this is distributor modding...but I do have two words to add: Black Box. Sorry.

[Clatter]

Pull the point plate and you can jam a screwdriver in there to bend the stops.

You’ll need a degree pulley, or other way of seeing what your timing is doing when you put the timing light on it.

Might take a few tries bending stops to get what you want with initial/full.

After you get your 10-12 initial and your 28-32 -whatever you’re shooting for-
Full advance,
You reset your idle speed/mixture,
And take the car out and see how it behaves.

Depending on how it acts, you might mess more with timing,
Or try tweaking the spring perches in there to stiffen/soften the springs and alter how the timing comes in ‘under the curve’ as they say.
Or you can use softer springs..
Or you can stretch them out to make them softer.


All part of the fun!
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Bus Motor Build

What’s That Noise?!?

[Bruce Amacker]

IIRC, when I did a new Pertronix a while ago, it had way too much advance also. It was set up differently, the limit was a pin that rode back and forth in a slot. I used a piece of tiny brass tube to sleeve the pin which made it larger and limited the advance. I'm thinking it had 30* (crank) of advance which didn't start until over 2500rpm and was all in by 4000 or so. This was a new dist right out of the box. It was a real pig to drive until I corrected this, if you set total to 30* it meant you have zero advance until over 2500. Ugh!
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'66 Deluxe Bus
'65 Standard Bus
Build threads:
'66- http://www.leakoil.net/forum/viewtopic.php?f=23&t=2888&sid=54d8dedfb3822f99c7f2ea430cb4e856
'65- http://leakoil.net/forum/viewtopic.php?f=23&t=4263

[raygreenwood]

[74 Thing]

[W1K1]

[FreeBug]

That's what mine does idles with whatever (i think about 10°)-as soon as you leave idle, bang, 15°.

[oprn]

[beetlenut]

[raygreenwood]

[Glenn]

Bending parts does not change the curve. it just changes where it starts and limits the total cutting off the top end.

If you don't know what you are doing, it's like setting the ignition timing by "ear". Your results will be unpredictable.
_________________
Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

Member #1009

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[spencerfvee]

[Glenn]