Ultimate 930 Distributor, advance, retard, timing, Turbo lag, MSD, mod, thread.

[mark houghton]

Originally Posted by 356-930

Some good engineering work Mark. And still no time to install that LM-1/2? Yeah, finally got her all installed early last spring.

Mark, since you/I purchased our trick MSD stuff, MSD has introduced a better, less expensive device, the programmable 6AL-2 @ $410 list. See specs @ MSD Digital Programmable 6AL-2 - 6530 Gonna have to take a look at that. I got off pretty cheap with a used MSD boost retard (already had the 6AL in the car), so my cost for this grand experiment was something like $125.

This system, like yours, is a poor man’s approach to distributor re-curving provided you don’t have to pay someone else to install and adjust. (But that’s true for any introduction of MSD’s ignitions to the 930). Always do my own work. Couldn't afford this machine otherwise!!

And, if doing the MSD dance, don’t forget to “fix” the rotor and change the spark plug wires! Done many moons ago.

Hey Chris, thanks for your comments. if you ever jump on the 6AL-2, would appreciate hearing how it works out.

[911st]

As of tomarow I am going to be out of town for 10 days but wondered if the following looks correct.

The On-Boost is seems to be the most open to change if we find out the solonoid dose close off idle, at 2800rpm, or with boost.

For now it looks like the dist retards with equal signels to each side of the pot.

Originally Posted by 911st

Mike and I have been working on some drawings and are posting them for review and approval if we can agree they are correct.

1)Cold start
2)Warm Idle
3)Cruse
4)WOT/On Boost

1) Cold start: shows no timing retard as both connections to the dist are blocked. The Thermo-Valve is blocking any resident boost and Solenoid is blocking intake vacuum. If either signal was to reach the pot, it would retard timing and not let is run a steped up idle. Solenoid bleeds any resident pressure in Pot to atmosphere. Also, AAR is open.




2) Warm Idle: Timing is retarded with combination of small resident boost that might be present from turbo at idle and mostly from intake vacuum.




3) Cruse. Butterfly moves past ported connections. The Boost-Retard side of pot sees vacuum and the Vac-Ret side sees modest resident boost and all retard function is suspended. (If there is any advance function we would see is by reconecting the pot and running up to 4000rpm.)




4) WOT/ On-Boost.
This may need to change. I now believe the dist is constructed so there are two diaphragms. One being the larger Retard diaphragm which can see boost pressure from both sides at WOT. The other being the Seal-Diaphragm that will push toward boost-retard and might be overriding the stalled larger diaphragm for a more progressive on boost-retard.

Thus, we show the no effect from the idle-solenoid. And, on boost we are showing boost to both sides of the pot and --full retard.

This is open for discussion.



Big thanks to Mike/copterdude for the wonderful graphics!!!

[mark houghton]

[QUOTE=hanson08;4942997]Most likely we will get to the end of the adjustment range available at the distributor before we reach the best advance for acceleration. I suspect about -15 is going to be a good place to be.
QUOTE]

True, in my case anyway. I was able to achieve no more than 8 degrees advance @ idle before running out of distributor adjustment room (fully rotated against the stops). That's 8 degrees with the vacuum retard hose connected. I know of at least one person that has run up to 14 degrees before detecting poor running. Each car, and each distributor curve, will differ - so what works for one may not work for another.
The car does not baulk and does get with the program better at the lower rpms. Would love to add a little more advance to find the limits, but it's not physically possible without removing the dizzy and re-indexing the drive shaft a tooth or so.

[911st]

Hanson08 might be some kind of scam or system being set up.

It looks like his post might be a test for a gold Internet marketer.

That was just a copy from my post #3 on the first page.

[JFairman]

C'mon Mark, slide it out, turn it a tooth, and slide it back in.

It'll probably jump a fence after that.

[mark houghton]

Originally Posted by JFairman

C'mon Mark, slide it out, turn it a tooth, and slide it back in.

It'll probably jump a fence after that.

I don't want to get my fingers dirty! Call me lazy, but it took me a full 20 minutes of miniscule turns of the nut with extremely inventive combinations of tools, just to adjust the timing. Might take all day to get the nut entirely off.

I'll get around to it one of these days, but first some mundane things like blowing out the yard sprinklers this weekend before the first 20 degree night that's forcast. Then, a blast up the canyon in that cold air at full boost.

[JFairman]

"Might take all day to get the nut entirely off."

oh.. guess i'll leave it at that

have a great weekend.

[mark houghton]

Originally Posted by JFairman

"Might take all day to get the nut entirely off."

oh.. guess i'll leave it at that

have a great weekend.

Thanks Jim.

You know, I'm one of those kind of guys that would like to think he has every tool known to man....until it comes to that stupid nut. Gonna have to fabricate one I guess. Won't be much longer in my neck of the woods before she gets put to bed for the winter anyway.

You have a great weekend as well.

[JFairman]

I use something like a 4" long 3/8 wobble extension and 13mm crows fot wrench and a small 3/8" drive ratchet with a flex head. It's not real tight and I use a nylock there.

I've seen sets of flex head crow foot wrenches with 8" handles. The 13mm looks like it would work.
Harbor Freight if you have them in the northwest has some that look ok cheap.

[ertech]

I not know if I am off topic ,just got my car back from the paint shop and wanted to do some testing with a wire going in the car to see if we have 12 v to the solinoid on boost .before I did that I wanted to test the distributor vacuum pods . used a vacuum pump on the boost side and it does hold vacuum . when I went to the solinoid side it does not hold vacuum at all , but the car runs great . I was thisking something was wrong before I read all these posts .when I removed the vacuum from the d=solinoid to the dist the iddle did not change ??
The car runs great just once in a while the iddle goes to 11-1200 rpm in stop and go trafic. can i drive the car like this or will I damage the car with the bad pod??
Thanks\
Erick

[Speedy Squirrel]

Originally Posted by ertech

I not know if I am off topic ,just got my car back from the paint shop and wanted to do some testing with a wire going in the car to see if we have 12 v to the solinoid on boost .before I did that I wanted to test the distributor vacuum pods . used a vacuum pump on the boost side and it does hold vacuum . when I went to the solinoid side it does not hold vacuum at all , but the car runs great . I was thisking something was wrong before I read all these posts .when I removed the vacuum from the d=solinoid to the dist the iddle did not change ??
The car runs great just once in a while the iddle goes to 11-1200 rpm in stop and go trafic. can i drive the car like this or will I damage the car with the bad pod??
Thanks\
Erick

Mine behaves similarly. Someone else on this thread reported that both sides held vacuum on theirs. I have a new one on order, so I hope that I can solve this discrepancy soon. From the drawing I have, I believe now that both sides should hold vacuum.

If you do not get the idle speed increase when you cold start the car (oil temp should be the same as ambient temp), then the diaphram is leaking too much to work. This assumes that all the parts that are required to drive the solenoid are still on the car and still working. Even when it will not hold a vacuum, the diaphram can still work when connected to a continuous vacuum source, like the the throttle body, depending on the size of the leak.

As far as damage, I do not think there is reason for concern. Leaking on the solenoid side will not prevent pressure timing retard from working.

Here is a picture of a test I did today on my diaphram. With pressure on both sides the rod extended only 0.1mm, which is within my experimental error. With pressure on the pressure side only it extended approximately 2.2mm. With pressure on the solenoid side only it retracted about 0.3mm.

From this I conclude that you cannot get pressure retard with equal pressure on both connections to the pot.

[JFairman]

I could take and post pictures of my mighty vac holding vacuum on each port individually, with my fingers off the pump handle...

[ertech]

why did you order one of the vacuum side is only needed when engine is cold ?mine holds zero pressure it feels like I am blowing through a straw.

[Speedy Squirrel]

I don"t use either side, as I use efi with full electronic timing control. I think these are going to be in short supply in the future, and I might want to switch it back to stock one day.

why did you order one of the vacuum side is only needed when engine is cold ?mine holds zero pressure it feels like I am blowing through a straw.

[ertech]

so acording to you guys the only fuction on the solinoid side if to help starting on a cold engine???do not want to order a 200$ part I do not need.

Thanks so much for all your help owning one of these cars would have been imposible without you guys .

[356-930]

Originally Posted by ertech

so acording to you guys the only function on the solenoid side if to help starting on a cold engine?. . . .

No.
Operation without the solenoid affects cold start idle.
Operation without the cold start "side" of the pot can and is done. But not without consequence (as discussed at length on this thread).
One side of the pot is vacuum retard (some call it vacuum advance) the other is boost retard.
In the linked post, the port visible is the boost retard port.
http://forums.pelicanparts.com/4946763-post231.html
Some here have found that boost pressure on both sides of the pot results in timing retard, others found different. (I was not smart enough to have tested my own distributor fully so I can't affirm).
Just how the device works seems to be different depending on engine year, distributor part number. (lots of detail info in this thread).
Bottom line: If you're running a stock engine or something close to it, need to comply with state emissions standards, replace it if it's bad. It does a lot more than aid (raise) cold start idle.

[ertech]

I have studied all that is writen here and still do not know what it does beside cold idle .what else is it good for ,
my car is a little modded with exhaust ,IC and K26-7200/
Thanks

[356-930]

Originally Posted by ertech

I have studied all that is writen here and still do not know what it does beside cold idle .what else is it good for ,
my car is a little modded with exhaust ,IC and K26-7200/
Thanks

That 'side" of the device (vacuum side) mechanically alters the distributor's moving mass to retard timing as affected by intake manifold pressure. It moves timing approximately 10 degrees positive as it looses vacuum signal.
Without it, timing at idle needs to be 10/12 degrees advance so engine can get to 28/29 deg above 3000 rpm, no load, to get power out of the fuel/engine.
Engine will probably misfire at idle due to too much timing, won't pass emissions. And, there will be no cold start high idle assist (which is the result of removing vacuum from the pot when the engine is cold).
What else is it good for? Runs cooler and idles smoother at idle, and assists in lowering emissions which makes tree huggers happy. Or, if one is looking for more off boost power, facilitates 10/12 degrees excess timing (to give you 20/22 degrees timing off idle/off boost to help wake up low end performance - provided however, one can get rid of the excess timing when the engine goes into boost. (It's but a small piece of the slippery slope.)

[964 T #304]

How dificult would it be to use a Megasquirt ecu to program the timming with and still run the cis injection. Those are pertty reasonable, but don't know about the reliability for use on our cars.

[Speedy Squirrel]

'Without it, timing at idle needs to be 10/12 degrees advance so engine can get to 28/29 deg above 3000 rpm, no load to get power out of the fuel/engine.'
the above statement is completely false. There is no vacuum to the solenoid side at 3000 rpm and no load, as the port is above the throttle. You get the same timing at the 4000 rpm check speed whether you have the hose connected or not. Anybody can verify this for themselves.