Re: normal distributor advance
[Re: warpspeed]
#477938
09/25/09 12:45 AM
09/25/09 12:45 AM
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Joined: Feb 2009
Posts: 982 W. Sacto CA. USA
phantomx
super stock
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super stock
Joined: Feb 2009
Posts: 982
W. Sacto CA. USA
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It sounds like your dist has 37 degrees of mechanical advance built into it, not good. Lets say your car likes the 15 degrees to idle, and runs perfect with 38 degrees total. Your dist should have 23 of mechanical advance. With your current setup at 35 total, your base would be 17 degrees after TDC, no wonder it won't start. Fix your current dist, or buy a new one. Travis..
70 GTX project, orig 440-4, 4 spd, track pack, FC7, stripper/street racer special.
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Re: normal distributor advance
[Re: warpspeed]
#477939
09/25/09 07:27 AM
09/25/09 07:27 AM
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Joined: Jul 2007
Posts: 531 Virginia
JimG
mopar
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mopar
Joined: Jul 2007
Posts: 531
Virginia
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Quote:
Now one other thing, the MP distributor has a vaccum advance in its pod. I tried to back it off ccw as Prof. Erhenburg says to do. It didn't change a thing. I backed it off three full turns without a change. Not sure that is normal.
What the allen screw does is change the amount of vacuum required to pull in the vac adv pot - it does not change the total amount of vacuum advance. You must shorten the stroke of the arm to do that.
If you crank the screw all the way in one direction (I forget which way it works) it might take 12-14" of vacuum to fully advance the mechanism. Screw it all the way in the other direction, it might take 5" to pull it in. It might pull in at idle (a bad thing). That's why it's best to know exactly how much vacuum is required for the diaphragm to begin to move, and how much for it to be pulled all the way in. Sometimes, I'll tee in a vacuum gauge to the vacuum advance, put the gauge in the car, and ride around to make sure it's pulling in under the right circumstances.
Leave the vacuum advance alone (and disconnected) until you get the initial timing and the mechanical advance right. Do those things first, vac advance last.
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Re: normal distributor advance
[Re: warpspeed]
#477943
09/25/09 11:48 AM
09/25/09 11:48 AM
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Joined: Jan 2003
Posts: 75,088 A Banana Republic near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,088
A Banana Republic near you.
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Quote:
Yep, yep, yep. You have hit the nail on the head. I am afraid I will run into the same problem with another "new" distributor though. I now have two distributors with the same problem. I hope I can fix what I have. Thank you.
stock mopar distributors have 30 plus degrees of advance in them so you aren't going to buy one that will just drop in .
IF you buy a NEW MP dist it has an adjustable mechnical advance , 40years too late , also in another thread on this subject a member that chimed in above sells a kit to shorten this without doing any welding to the dist .
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Re: normal distributor advance
[Re: JimG]
#477944
09/25/09 01:40 PM
09/25/09 01:40 PM
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Joined: Apr 2003
Posts: 3,968 North Riverside IL & Lowell IN
GTXKen
super gas
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super gas
Joined: Apr 2003
Posts: 3,968
North Riverside IL & Lowell IN
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Quote:
Quote:
Last question, how do you fix this? Recurve by adding metal to the slots? I belive that is what Rapid Robert is talking about.
Attached is a photo that shows the slots in the process of being modified with JB Weld (not recommended) but you can see the proceedure nevertheless. One slot has been filed to the desired length (see the chart Rapid Robert is sending) and the other slot has been shortened, but not yet filed.
Distributor recurving is one of those basic things you must do when the camshaft is changed to one with sportier valve timing.
Would anyone care to send me or post this here chart you are speaking of?
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Re: normal distributor advance
[Re: RapidRobert]
#477954
10/12/09 01:52 PM
10/12/09 01:52 PM
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Joined: Jun 2009
Posts: 101 South Carolina
warpspeed
OP
member
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OP
member
Joined: Jun 2009
Posts: 101
South Carolina
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Finally, guys and gals, I only have one thing to say about my electrical system problems, WOW! I have finally had the time to tear one of my distributors down and "weld and grind" down the slots. This was described as 'recurving' the distributor. My first request for help came with a one sentence response; -check the ground-. Well, I can tell you sincerely- I checked the ground. Everywhere! Couldn't find anything wrong with it. But, the problem persisted. The new MSD Street fire unit I purchased wouldn't work, but everything continued to check out. The timing was showing 52 mechanical at 3,000 RPM. I worked at everything I could remember to FIX the problem(s). Finally rapid robert instructed me to "recurve" the distributor. Well, I am here to tell you that it helped, but, I was still off. Finally, I removed the MSD, it would only work part of the time anyway. You could tell that it wasn't sending fire along the system. I still can't get the MSD to work at the moment, so the Chrysler ECU stays on for a while. I also removed the adjustable rockers, ouch! I finally had to start over again with the basic engine, still without sucess. Then, by accident, I touched the ground cable terminal at the battery after an episode when trying to start the engine. OUCH! That sucker was hot! The brain starts working and I think "bingo", so I decided to swap the ground cable from my 70 TA. Hold up there horsey, the car fired right up! I adjusted the timing and took it for a ride. WHAT a difference! The ground cable was a number 2 wire with a very good clear plastic cover that showed nothing wrong with it. BUT, the wiring inside the terminal on the battery was not very well connected. I wasn't able to see the problem because it was under the metal of the terminal connector. There was no corrosion or anything else to indicate a problem. But, resistance must have been up and the amperage was not be able to get through, I guess. Once, the ground wire was replaced, everything started to come into its own (the MSD still won't work). The timing was down (before the recurving) to 45 (from 52) at 3000+. Once recurving, the timing is now at 35 @ 3000. (This a 440) This car has never run this well. The engine doesn't sound like it is missing. It is responsive like my small blocks. Running down the street, I can touch the accelerator and there is an immediate response. Gee, can you say "beautiful"? Thank you Rapid Robert and the rest of you for your information, encouragement, and etc. Its is great to have a 'HOT' running car. All I can add to this is that if all the wiring and components are properly working and connected, these old systems are easier to diagnose and fix. AND CHECK THE GROUND.
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