Position of distributor cap to no. 1 plug 258

**EngChase** · 03-09-2010, 08:03 PM

Help me out on this, look at this picture specifically the distributor cap and wires. I have seen other engine compartments on here and the number one plug wire is located more toward the passenger side of the compartment and the vacuum advance is typically pointed toward the front of the jeep. On my jeep the number one is connected to the post closest to the engine (driver's side of distributor) and the vacuum advance is pointed toward the right front tire. The plug wires match up to the firing order in the FSM, but they are not oriented on the distributor cap and the cap seems out of position. The jeep runs pretty good, other than a rich condition and getting about 10 mpg. Should I try to find TDC and realign the distributor, or is this even an issue? Thanks for your help.

Fatman · 03-09-2010, 08:08 PM

It's all in how the distributor BODY is set.

Felonious_monk · 03-09-2010, 08:16 PM

Quote:

Originally Posted by engchase

Help me out on this, look at this picture specifically the distributor cap and wires. I have seen other engine compartments on here and the number one plug wire is located more toward the passenger side of the compartment and the vacuum advance is typically pointed toward the front of the jeep. On my jeep the number one is connected to the post closest to the engine (driver's side of distributor) and the vacuum advance is pointed toward the right front tire. The plug wires match up to the firing order in the FSM, but they are not oriented on the distributor cap and the cap seems out of position. The jeep runs pretty good, other than a rich condition and getting about 10 mpg. Should I try to find TDC and realign the distributor, or is this even an issue? Thanks for your help.

It doesn't matter what way the distributor is pointed. You could take it out and reposition it, but why? It has absolutely no effect on the way your Jeep runs.

**swatson454** · 03-09-2010, 08:19 PM

As long as the firing order is correct and you have plenty of room to adjust the timing, it's totally up to you. I do have a question though. Does the number six spark plug have a tendency to run lean or oil-foul?

If so, you may want to give some consideration to moving that PCV inlet somewhere close to the plenum, if you have a port there anyways.

Your engine compartment reminds me of all the california smog wiring crap I need to remove from mine. I can't even see the firewall, lol. Yours looks clean and neat.

Shawn

Racing Carburetors

**EngChase** · 03-09-2010, 08:29 PM

I've had this jeep since last July. The PO had the engine rebuilt and this is "how it was" when I got it. I'm glad you asked about the PCV. The number 6 is the only one that doesn't run rich. I had a feeling that the PCV connection may be affecting the no. 6. I'll connect it to the port next to the power brake connection and see if that makes a difference.

**Mike Romain** · 03-10-2010, 05:19 AM

Your distributor is just 'clocked' differently than stock. When it is installed into the engine, the rotor can point any direction. As long as the wires match up to where the rotor is pointing, this clocking doesn't matter 'too' much but...

In the stock position, only two spark plug wires physically cross each other close enough to maybe cross fire or misfire. Yours has a whole bunch of the wires crossed which makes for a higher likely hood of a misfire. In a perfect system, no high voltage wires should cross.

deadeye · 03-10-2010, 07:17 AM

Quote:

Originally Posted by swatson454

I do have a question though. Does the number six spark plug have a tendency to run lean or oil-foul?

If so, you may want to give some consideration to moving that PCV inlet somewhere close to the plenum, if you have a port there anyways.
Shawn

Shawn, could you go into a little more detail please.

This is something I have never hear till now.

sorry don't mean to hijack but I would like to know more and the poster did say #6 was the only one that didn't run rich.

AlbuqHenry86cj7 · 03-10-2010, 07:30 AM

Quote:

Originally Posted by deadeye

Shawn, could you go into a little more detail please.

This is something I have never hear till now.

sorry don't mean to hijack but I would like to know more and the poster did say #6 was the only one that didn't run rich.

Mine is set up just like in the picture.... See the pcv valve in the front of the valve cover? That vac line goes into the intake manifold very close to number six.. so chances are that number six is getting the most of the "air" that is coming from the crank case.... in this "air" there is no fuel which will make number six run lean. Also in this "air" is possibly oil mist and all the stuff that is not suppposed to go into the atmosphere (sp.?) and burning this might foul the plug.

I dont have another port available except for my brake booster and one little one at the base of the carb. I have only been driving the jeep for a few days so chance yet to see how the plugs look....

**Mike Romain** · 03-10-2010, 08:24 AM

Quote:

Originally Posted by AlbuqHenry86cj7

Mine is set up just like in the picture.... See the pcv valve in the front of the valve cover? That vac line goes into the intake manifold very close to number six.. so chances are that number six is getting the most of the "air" that is coming from the crank case.... in this "air" there is no fuel which will make number six run lean. Also in this "air" is possibly oil mist and all the stuff that is not suppposed to go into the atmosphere (sp.?) and burning this might foul the plug.

I dont have another port available except for my brake booster and one little one at the base of the carb. I have only been driving the jeep for a few days so chance yet to see how the plugs look....

That is the proper way a 258 should be plumbed with that air filter. Maybe the photo was just deceiving?

EDIT: photo 'was' deceiving, the PCV is going to the back of the manifold into #6 as mentioned, not the base of the carb where it is supposed to go...

I have insane blowby right now from one dead cylinder to the point of popping the PCV valve right out and my # 6 plug looks the same as all the rest. (Mine goes to the carb base though)

**swatson454** · 03-10-2010, 08:40 AM

Quote:

Originally Posted by Mike Romain

That is the proper way a 258 should be plumbed with that air filter. Maybe the photo was just deceiving?

I have insane blowby right now from one dead cylinder to the point of popping the PCV valve right out and my # 6 plug looks the same as all the rest.

Could be deceiving my eyeballs but #6 does appear to be taking in every bit of blowby. As Mike mentioned, the blowby doesn't have any measurable amount of fuel in it. As if that isn't bad enough to draw in straight air, the oil vapor will reduce the octane rating of what ever fuel is allowed in.

I bet if you put your fingers on the valve while it's running, it pulses like crazy too. I wonder if that will cause a premature failure of the valve.

But if that's the way they did it on that year and you don't have any other option, what can ya do? Ya know?

Shawn

**swatson454** · 03-10-2010, 08:56 AM

I bet you could switch it with the brake booster's vacuum source. Maybe?

Holley carb tuning

**Mike Romain** · 03-10-2010, 09:09 AM

Quote:

Originally Posted by swatson454

I bet you could switch it with the brake booster's vacuum source. Maybe?

I would, a T fitting off the booster line would be fine for it.

Your eyes were right, mine were wrong, the PCV line should go to the base of the carb and it should be picking up the gas tank vent line (canister purge). gas tanks don't like to have no vent, they vaporlock starving the engine for fuel.

**EngChase** · 03-10-2010, 04:42 PM

I'm going to switch mine to the brake booster line and see if that helps. I also have smaller jets coming for the MC2100 this week. I am running 48's at 2200' of elevation. Thanks for help guys.