[swa240z]

I'm wondering if fuel pressure is an issue on my setup. I have some quirky tuning issues that I can't seem to resolve. Where did you get your fuel pressure regulator and how much? Thanks.

Steve

[zeus87gn]

Hey Steve,

It's that Mr. Gasket universal regulator that they've been making for years.
Got it from my local CarQuest for about $25.
They had it on the shelf.
Body is Crome (probably nickel plated brass) with brass fittings.
I didn't care for the clamps that came with it so I used the typical ones.

Patrick

[Jungle]

zeus87gn,

In reading your post It sounds like my problem exacto.

I have 87 with 4.2L w/ Holley Carb. Not sure which model CFM but the symptoms you mentioned is exact match with mine. This give me a new direction to start checking now. You mentioned that someone made the adaptor for you? Is this correct? Overall vacuum leak was the main culprit of problems?

Also in your pictures posted it appeared that you have a vacuum line going to the "ported" vacuum on the side of your carb. Is this from the distributor vacuum advance? Mine will not run properly with ported vacuum. I have to take distributor vacuum advance direct from below throttle plates.

Has your jeep been "Nuttered"?

Thanks again for Post. I just happen upon it today for first time and excited to have a new direction.

[zeus87gn]

Originally Posted by Jungle

zeus87gn,

In reading your post It sounds like my problem exacto.

I have 87 with 4.2L w/ Holley Carb. Not sure which model CFM but the symptoms you mentioned is exact match with mine. This give me a new direction to start checking now. You mentioned that someone made the adaptor for you? Is this correct? Overall vacuum leak was the main culprit of problems?

I will guess you know if it's a 2 or 4 bbl. Look on the air inlet bell (housing that is sticking up) and see if there is a 7448 stamped into it. If so, you have the same as I, the universal 350cfm. If it's something else, check it out on the Holley web site tech library.
http://www.holley.com/TechService/Library.asp

Yes, I believe the leaking universal (cheapo piece of junk) adapter plate was causing my problem of not being able to tune it correctly. I had a pro engine shop close to me custom make these adaptor plates. They were machined out of a solid block of alum. It wasn't cheap, but worth the $$ in my opinion.

Originally Posted by Jungle

Also in your pictures posted it appeared that you have a vacuum line going to the "ported" vacuum on the side of your carb. Is this from the distributor vacuum advance? Mine will not run properly with ported vacuum. I have to take distributor vacuum advance direct from below throttle plates.

Has your jeep been "Nuttered"?

Thanks again for Post. I just happen upon it today for first time and excited to have a new direction.

Correct. The ported vacuum is dedicated for the advance on the dist. Taking vacuum from below the throttle plates would be manifold vacuum. You are running your dist at full advance. You have it timed wrong. It may not hurt anything, but you aren't making full power from your motor. And probably getting some lousy gas mileage.

Yes, I have my system bypassed. It was one of the first things I did to solve a bunch of problems. If you do as well, set your timing at idle speed, not 1600RPM as some books say to. The motor should idle with no problems and no vacuum advance. Connect your ported vacuum back to the dist advance and put on your seat belt.

[Brandon_YJ]

The adapter plate that the PO used when he put my 350 on a few weeks before I picked up the Jeep seems to work out alright. I thought I had a vacuum leak but that wasn't the issue, guess I lucked out on that one.
Are you using an electric fuel pump? I didn't think a mechanical pump could put out enough pressure to require a regulator.
Is it even possible to have a 350 on your rig without nuttering? Serious question here, I just can't see how it would work out without bypassing the computer in the first place.

I'm very happy with my 350, once I jetted it down to 58 it has been awesome.

[zeus87gn]

Yep, mechanical FP here. It's not very old. Brand new unit from the 'Zoo. I guess the remans are too old to reman anymore.

I agree. I wouldn't think the engine would run right unless you did do the bypass with the Holley. Lots of reading in the YJ pages of engines that won't keep the timing in spec until after the bypass.

Do you know what type of plate he put on there?

The 58's seems to be the magic set for the 4.2l

[Brandon_YJ]

Not sure what plate he used. I have yet to rip into the engine compartment since it's running decent at the moment. Doing body/tub work now, engine later.

The only reason I don't believe the plate is leaking is because it passed the "starter fluid" test. But that still doesn't give me 100% assurance.

[zeus87gn]

Spraying the fluid is a good indication for an external leak.
You may want to check the baseplate gasket.
When you get the time, pull the carb off the plate and look at the gasket. If you have the universal adaptor plate, there will be slots around the mtng bolts that hold the plate to the manifold. Look at the gasket in these areas. If the gasket appears discolered, it may be leaking internally to the carb. Internally as in not having the correct airflow and fuel metering (carbs work solely on vacuum). This is what was wrong with mine.

You say yours is running fine right now, probably best to wait until you finish your other work to investigate. These problems have driven me nuts so I went after them and let other stuff wait. Like lift kits and gearing and...

[Brandon_YJ]

I'll keep all that in mind and after the body/tub are done I'll look into it.
Right now I have my hands full.

[Jungle]

Yep, I checked the carb (2bbl by the way) and there is a 7448-1 stamped on it.

Some History here. Jeep is 1987 with a rebuilt 4.2L 258 Engine. Recent "project vehicle for me" it has the Holley Carb mentioned already on it when I bought the vehicle. Vehicle ran ok in my opinion especially at the higher speeds but never really idled well. So In my investigating and readings thru this forum I found out that with the Holley carb that the vehicle might have issue with the ECM. So I checked to see if vehicle had been "nuttered" which it had not so I preformed the Nutter By Pass my self. Timed at 8 degrees just like the instructions said. By the way the vacuum advance was hooked to manifold vacuum and not "ported", apparently by the previous owner, but I did unhook and plug this vacuum line when setting timing. The results after the nutter showed no real change in idle preformance maybe even slightly worse.

I have jacked around with the mixture screws on sides of carb only to return to previous settings which are out about 1-1/2 turns each.

Removed and checked spark plugs and did notice a black burnt area on one side of the plug on each and every cylinder.

Checked ohm's on spark plug wires. Which look good.

I have checked just about everywhere for a vacuum leak and could not find any. After reading this forum I now suspecious of the carb adaptor to the intake althought I see nor feel/hear any leaks. My adaptor plate looks like a 1" plastic or rubber type setting directly on intake manifold with an 1" aluminum plate on top of it then the carb.

Might add that with the Vacuum advance hooked to "ported" vacuum as you suggest I measure only 15-17" of vacuum off of the manifold vacuum lines.

I think that I'm getting there with everyones help in this forum.

Thanks

[zeus87gn]

Jungle,

Good for you if you have performed the bypass and it's stil running.
I shorted my box in the process and had to buy a new one.
You have the same carb as I do.

Wow, 2" of spacing b/w the manifold and carb!
You must have a short air breather to clear the hood.

8* is a good start. You may change it before you are done. Every motor is different. I'm running at 12*.

17" of vacuum is a little low. I'm running 22" if memory serves. You say the plugs looked burned black. They should be grey. My guess right off would be carbon(ed) up valves giving you low compression as you are probably running rich at 1-1/2 turns. I'm at about 3/4 the first turn.

Do you know what jets you have in the metering block?
What gas do you run?
Have you ever done a compression check?
What plugs do you run?
Do you still have the cat conv?

Something else to check is your manifold bolts. The original bolts like to work loose from age and will cause a vacuum leak. If you find them loose, tighten them to (I believe) 42lbft. If they loosen back up in a month or two of driving, replace them with new ones.

[swa240z]

Hey Patrick - I swapped out my jets for 58's as you and others have suggested. The carb setup seemed a little fat prior to the swap, but now runs VERY well. Thanks for the tip!

Steve

[zeus87gn]

Hey Steve,

Glad it's running well.
The 58's seem to be the ticket for this setup!


Patrick

[zeus87gn]

Well, thanks to Jungle I have found a picture of the old adaptor plate I couldn't get to work.
Just for the record, here is that piece of junk - Mr. Gasket #1937:
http://www.partsamerica.com/ProductDetail.aspx?MfrCode=MRG&MfrPartNumber=1937& CategoryCode=3575Y

There are some other plates on that web site that look like they might work, but I wouldn't know for sure.

[china-clipper]

Thought I'd resurrect this thread if anybody else is using a Holley 350 out there; tons of info....excellent thread. I may try and make my own adapter; my dad has a Bridgeport milling machine. Gonna check my jets and see what's in the carb now.