This thing is pointless

[KenB]

OK, help an old guy get up to date. I've made a few changes:
Exhaust - removed cat, increased to 1 7/8" pipe, hi-flow muffler
Carb - Replaced pre-electronic BBD with MC2100
Removed some of the emissions stuff that was no longer hooked up, and plugged ports/hoses.
After the exhaust work, I noticed a "marbles in a tin can" rattle when accelerating under load (can't hear it no-load), and suspected timing.
Set timing to 8 BTDC at 700 rpm. That reduced the rattle, but didn't eliminate it. Some time passes and I can't tinker with it for awhile, but get to do a little studying. One thing I find (that I should have remembered) is to set the dwell before the timing. Hooked up the dwell meter, and it's reading a solid, steady 48. Hmm, specs for the engine say 31-34. Okay, I need to adjust the points. Popped the distributor cap (Motorcraft) - NO POINTS!!
So now I'm confused. How do I adjust dwell - or do I need to?
Is there something else I should be looking for to eliminate the pinging? (The vacuum advance seems to working i.e. it moves if I suck on the hose, but no idea how much vacuum that is. I have read that there may be an adjustment in the vacuum advance canister, but haven't tried that yet. If it is in there, have no clue as to how much adjustment to make.)
Sorry to be so long winded, but I don't know where to go from here.

 

[DREDnot]

Ya got me with your thread title...good one.

Your pinging could be caused by no EGR.
In your vacuum hose disconnection frenzy, you may have disabled the EGR system. This is not ONLY for emissions but helps eliminate spark knock.

Make sure that it is functioning properly before possibly setting off in the wrong direction.

 

[Old Dog]

No points no dwell it controled by the module.
If there is an adjustment in the vac. advance, it would adjust with a little allan wrench. Counter clockweise usually backs the timing rate down.
Try a 3/32 and go one whole turn at a time.
You might also want to check the springs on the mech. advance, they may be getting weak or the bushings might be getting wore out.
I'd try 6* first to see if that helped.

 

[KenB]

The PO had plugged off the EGR, so I hooked it back up. Plugged the hose into the port by the left hand mixture screw. Thought the dam thing was going to croak the first time I got on the skinny pedal. Improved a bit after a few miles, but still p-poor acceleration from a standing start (better without the EGR hooked up), and still getting the rattle under load. Ran out of time today, so may try the vac advance adjustment tomorrow. Good to know I don't have to worry about dwell - thanks OldDog.

 

[IOPort51]

do you have a vacuum leak in the EGR diaphragm??

 

[KenB]

Well, IO, that does seem to be another part of the puzzle. Definitely seems to be a leak in the diaphragm. Like sucking through a straw, and no movement. Pulled it out, and the plunger is free. Wouldn't have suspected that, since it's obviously a fairly new EGR, but then, maybe that's why the PO had it plugged off. Should have a new one Saturday morning, so will wait before messing with anything else. I've learned to do one thing at a time so I don't have to remember so far back when I screw up.

 

[IOPort51]

I think the EGR is supposed to be controlled by the thermostatically controlled valve on the driver’s side of the block but it has been a while. Information on emissions stuff is hard to come by when you want it. Let me know what the new EGR looks like, the last one I replaced had little orifice washers that you matched with the size of the original hole, I don’t know if I ever got that thing just right before the little washer got stuck and I couldn’t change it again. It may be a good idea to check the exhaust manifold where the EGR connects and be sure it isn’t full of black soot.

 

[KenB]

That's something else I've been wondering about. The diagrams I've found so far show the EGR hooked up to a CTO (alphabet soup). This thing appears to have two temperature sensing devices hooked together by a spaghetti bowl of vacuum lines. Both are in the water jacket. The first one only has lines to the second one, and the second one has lines to the carb, the EGR and the canister. ???

 

[dslywalker]

I have a FSM on a 81 if you need some info from it.
Mike

 

[KenB]

Thanks, Mike, I would appreciate some info when you have a chance. I'm curious about the two sensors.



Lousy drawing, but this is the way they are hooked up:

 

[IOPort51]

the diagram is ok but you have to find out which port goes to which port when it is cold and when it is hot.

Thanks, Mike, I would appreciate some info when you have a chance. I'm curious about the two sensors.



Lousy drawing, but this is the way they are hooked up:

 

[dslywalker]

Here's the vacumn for a manual and auto trany.I believe you had a auto.This is for 49 states and not California diagrams
Good Luck let me know if you need anything else
Mike

 

[KenB]

Thanks for all the help guys. Got the new EGR this morning. The box included two packages of orifice washers!! Instructions say to select the orifice washer according to the original OEM EGR. Now this took some digging, since the one on there was not original. After a lot of searching, it seems the original was supposed to be a GM 1708395 (for a CA auto Transmission ). The selection chart says "N/R", the old didn't have one, so I left it off. Anyway, after the install and a warm-up, me and the little dog went for a ride. What a difference! No ping, and the best acceleration it's had since I got it.
Mike, I checked out the diagrams you sent, and there is a lot of difference between it and what I have plumbed. Maybe because it was originally a CA rig? One thing - on both the Auto and Manual diagrams, it shows the Vac Advance to the Distributor coming off the CTO (on the Auto it's 'modified vacuum', and on the Manual it's 'ported vacuum'). Maybe a BBD thing? The old carb on mine was a pre-electric BBD and it ran ported vac from carb to distributor. Same on the new MC2100.
Anyway, it's running great right now, so I ain't gonna fix anything else till it's broke (this week anyway).

 

[dslywalker]

I have the ones for California too.Seen you were in Tx. so sent the other.If you need them I'll post them.
Mike

 

[KenB]

Hey, Mike, I'd appreciate that. I'm slowly cleaning up the mess under the hood, and trying to keep it running at the same time. PO had disconnected/plugged off some lines and ports, and possibly rerouted others. When I bought it, it had a CA title. But, I bought it in TX, which might give some hint to it's emissions capability.
Funny/good thing today. When I first bought it, the wife's car was having some brake problems and she was afraid to drive it. So she opted to drive the Jeep on her weekly Walmart run (with sloppy steering and p-poor acceleration). She hasn't driven it for almost a year now, until today. First comment: "Wow, this things got some power now!" Second comment: "I can keep it between the ditches!" She's gonna be a 69 year old jeep girl.

 

[dslywalker]

Glad she likes it now.My wife wouldn't be without her Jeep.She's 60 and will drive it till she can't anymore.I just get to work on it.
Mike