Ignition, Plugs and Timing

[custom76]

Just replaced carb with another Performer mounted on Edelbrock manifold. Engine has a miss we can’t seem to chase out, so I’m going to start with a new set of plugs and I’m questioning the ignition module connected to the MSD set up.

All was by PO, fixed incorrect vacuum hose hookups, replaced bad vacuum pod on distributor and timing advances from base of 13 degrees to 33 degrees now.




Sent from my iPad using Tapatalk

[Curly]

That Wells box is the voltage regulator for the alternator.

[will e]

Since it was installed by a PO let's check a basic thing.

Confirm if the new coil is an 'internal' or 'external' resistance coil. If it is an 'internal' resistor coil then confirm the voltage on the coil positive side with the ignition turned 'on'. The jeep doesn't have to be running. If it is lower than 11 volts, then there is a resistor wire in the circuit. An internal resistor coil wants 'all 12 volts'. The simple fix is to add a relay using the current coil wires as the trigger.

[custom76]

That Wells box is the voltage regulator for the alternator.

Electrical is obviously not my strong suit. Then this component seems to be functioning fine. Thanks

[custom76]

Since it was installed by a PO let's check a basic thing.

Confirm if the new coil is an 'internal' or 'external' resistance coil. If it is an 'internal' resistor coil then confirm the voltage on the coil positive side with the ignition turned 'on'. The jeep doesn't have to be running. If it is lower than 11 volts, then there is a resistor wire in the circuit. An internal resistor coil wants 'all 12 volts'. The simple fix is to add a relay using the current coil wires as the trigger.

The coil is not new, the MSD Blaster is also from the PO’s setup. My brother in law is helping me through this and likely knows just what you mean. I have learned a great deal from Mac over the years. I’ll be back in touch if he has any questions. Thanks

[babywag]

Which MSD distributor does it have?
8519 or 8523(internal ignition module)?

Coil wire looks sketchy, spray all wires/cap with a spray bottle filled with water @ night in dark while engine is running.
If you have any bad wires you'll see & hear them arcing.

[custom76]

Which MSD distributor does it have?
8519 or 8523(internal ignition module)?

Coil wire looks sketchy, spray all wires/cap with a spray bottle filled with water @ night in dark while engine is running.
If you have any bad wires you'll see & hear them arcing.

I am unsure, how do I tell the MSD model?
Thanks for the test tip!

[custom76]

Which MSD distributor does it have?
8519 or 8523(internal ignition module)?

Coil wire looks sketchy, spray all wires/cap with a spray bottle filled with water @ night in dark while engine is running.
If you have any bad wires you'll see & hear them arcing.

This is my model.
MSD 8523 Distributor Pro-Billet Ready-to-Run Magnetic Trigger AMC

When we ( meaning me and my electronically smarter brother in law Mac) get one aspect of engine performing well it puts something else out of whack, I.e., got it idling and mostly starting well (occasional lag), but doesn’t take gas on acceleration as well as it should and we’re setting on 22 degree advance right now which is a lot higher than specs say to do but much lower it falls apart, changed out carb to new Edelbrock 600 and new vacuum advance pod installed, vacuum ported to LH side, timed vacuum on upper plate I think.

Update, today it lugged, backfired thru carb and didn’t start. Mac thinks I might need to go to a stock distributor.

Truck has not been run on road since these were done, strictly garage tuned for now until I get hood back on and few other things finished before I can.

Thx

[babywag]

verify plug wires are correct firing order
check cam gear and distributor gear. have to remove distributor to check them.
if stripped/chewed teeth you'll never get it to run right.

many times aftermarket distributor gears eat up old cam gears.

[letank]

When you get it running.... you said edelbrock 600cfm, is it a 1406? Make sure that it is plumbed as per specs, the PCV valve layout is different than our stock 2150

If there are no vacuum leaks tested with your favorite spray around the carb base, be sure that you do not read false positive by the spray being sucked into the air filter , not too sure of your air filter set up.

What vacuum manifold reading do you get, above 15" and somewhat steady? Using the strobe light on every spark wire, is it lighting consistantly?

Then time for compression check...

[custom76]

When you get it running.... you said edelbrock 600cfm, is it a 1406? Make sure that it is plumbed as per specs, the PCV valve layout is different than our stock 2150

If there are no vacuum leaks tested with your favorite spray around the carb base, be sure that you do not read false positive by the spray being sucked into the air filter , not too sure of your air filter set up.

What vacuum manifold reading do you get, above 15" and somewhat steady? Using the strobe light on every spark wire, is it lighting consistantly?

Then time for compression check...

Yes, 1406, I’ll double check all plumbing, but pretty sure it is correct. I’ll get some closeup pics to send.

I used a brake line cleaner which is pretty flammable, was out of starting fluid, to check vacuum yesterday. What spray do you use?

Air filter is bone stock.

Will check vacuum pressure when I get a gauge, do I want a PSIG gauge.

Did not test every wire with light, will do that.

Thanks and have a great Sunday!
Steve

[custom76]

verify plug wires are correct firing order
check cam gear and distributor gear. have to remove distributor to check them.
if stripped/chewed teeth you'll never get it to run right.

many times aftermarket distributor gears eat up old cam gears.

After going thru Letanks list, I’ll do this if it gets that far, could possibly be that as I was told PO freshened motor with rings and had heads done, no knowledge on much else, don’t even know if top end changes were made at same time, could have been later (or sooner).

Thanks much!
Steve

[letank]

Yes, 1406, I’ll double check all plumbing, but pretty sure it is correct. I’ll get some closeup pics to send.

I used a brake line cleaner which is pretty flammable, was out of starting fluid, to check vacuum yesterday. What spray do you use?

Brake cleaner too

Air filter is bone stock.

make sure that the air flappers are operational and not obstructed, 76 should not be an issue, but who knows which air filter casing was installed, you can always run with the top off, unless there is a sandstorm brewing

Will check vacuum pressure when I get a gauge, do I want a PSIG gauge.

Vacuum gauge units are in of Hg (mercury) the other scale can be mm of Hg, or get a hand vacuum pump, always useful to test all our vacuum operated gizmo.

Enjoy your day

[dbx11]

I had a major tuning problem before I decided to pull the engine and have another member rebuild it, It was pretty tired and the timing chain had stretched a lot causing ignition,timing issues. It would run but I always had problems I couldn’t iron out. If you can search for chain replacement symptoms it might lead you towards all of your issues.

[custom76]

I had a major tuning problem before I decided to pull the engine and have another member rebuild it, It was pretty tired and the timing chain had stretched a lot causing ignition,timing issues. It would run but I always had problems I couldn’t iron out. If you can search for chain replacement symptoms it might lead you towards all of your issues.

Thx, I’ll add it to my growing list!

[custom76]

When you get it running.... you said edelbrock 600cfm, is it a 1406? Make sure that it is plumbed as per specs, the PCV valve layout is different than our stock 2150

If there are no vacuum leaks tested with your favorite spray around the carb base, be sure that you do not read false positive by the spray being sucked into the air filter , not too sure of your air filter set up.

What vacuum manifold reading do you get, above 15" and somewhat steady? Using the strobe light on every spark wire, is it lighting consistantly?

Then time for compression check...

I’m slow but steady, truck passed carb base leak test and vacuum holds steady at 16 1/2, on to strobe test next round, u may be on your way to those seals! Your contender seems to be cam gear post, only other I can think of is if my internal mechanical advance springs are weak or need adjusting (outside my pay grade). Thanks letank.

[letank]

When you get it running.... you said edelbrock 600cfm, is it a 1406? Make sure that it is plumbed as per specs, the PCV valve layout is different than our stock 2150

If there are no vacuum leaks tested with your favorite spray around the carb base, be sure that you do not read false positive by the spray being sucked into the air filter , not too sure of your air filter set up.

What vacuum manifold reading do you get, above 15" and somewhat steady? Using the strobe light on every spark wire, is it lighting consistantly?

Then time for compression check...

I’m slow but steady, truck passed carb base leak test and vacuum holds steady at 16 1/2, on to strobe test next round, u may be on your way to those seals! Your contender seems to be cam gear post, only other I can think of is if my internal mechanical advance springs are weak or need adjusting (outside my pay grade). Thanks letank.

16 1/2 steady is good, really steady is excellent in fact, when I had a wiped 2 flatten lobes on the cam it was about the same but with a lot of flutter and big puffs or unburn oil out the tailpipe after rapid throttle acceleration.

you can try to play with the idle mixture screw and see if the vacuum goes up a little 1/8 turn at a time.

Otherwise, on my project it was running fine after the camshaft swap, but after it reached operating temp it was stalling everytime I put in gear or at a stop sign, which did not happen with the wiped out cam lobes ... so I found the carb base leak... I say perfect, but It did it again after warm up... now I was 200 miles from base... dang... so I increased the idle speed and dealt with it ... to find out that the mixture was way too lean... it fixed the stalling after warm up.... to complete the story, I decided to check the main jet -I have the OEM carb 2150-, it was jetting for high altitude with #50... installed #55, but with the dam virus, there is really no place to go. Clean up the garage

Good luck