Rough Idle / Intake Backfire / Stalling

Hello,

First 3 weeks of ownership jeep ran fine. Then started having very rough idle and intake backfire when reving. When engine warmed up would run better but still bad. Replaced plugs, rotor, redid timing ran better but still poor especially when cold.

Had factory ignition system. So I pulled the factory ignition system and replaced with HEI system and new plugs.. http://picasaweb.google.com/BrentHostetler/CJ5CarterYFCarbAndRelated/photo#5142042332045233314
Old plugs (less then week old) 1st and 6th cylinder plug lean but inner plugs badly fouled. Started right up immediately better No rough idle. It has been about a week and temperature has droped ( colder now ) and its idleing real rough when cold after 15 minutes runs real good. If try to take off to early may missfire through intake.

So after looking around I believe I have a Carter YF single barrel carb. I thought I had the dreaded Carter BBD so I bought a motorcraft 2100 ( cant install yet cause now need new intake) http://picasaweb.google.com/BrentHostetler/CJ5CarterYFCarbAndRelated/photo#5142042585448303874

The installed carbs choke is not working. Looks like when PO installed headers he removed some heat pipe that activates choke ??? http://picasaweb.google.com/BrentHostetler/CJ5CarterYFCarbAndRelated/photo#5142042856031243650
Looks like he removed a lot of the emmission stuff and bypassed EGR. Looking in FSM looks like maybee the vacuum advance for distributor is wrong too. He had on port that is high up by air filter on passenger side of carb I dont seem to feel any vacuum on this port at idle or high rpm. At base of carb there are two ports on passenger side it looks like the front one should be for distributor advance from looking at FSM but changing doesnt help. I dont think the vacuum advance is working.

On drivers side of the block there are two plugs looks like part of vacuum system that have been bypassed. http://picasaweb.google.com/BrentHostetler/CJ5CarterYFCarbAndRelated/photo#5142042770131897682
http://picasaweb.google.com/BrentHostetler/CJ5CarterYFCarbAndRelated/photo#5142042791606734178
There has been so much changed from factory vacuum system kind of at a loss of whats been done right/wrong and what could be causing problems.

Ultimately I will be putting the motorcraft 2100 on once I get a new intake ( trying to find one of the newer aluminum intakes with the heater maybee that will help ). Untill then I need to get this running better. First will be to install a manual choke, but all the other changes kind of have me at a loss what to do.

Any suggestions?

Thanks... Brent

 

You can use an adapter for the 2100 onto a 1v stock. A huge improvement. A 2v would be even better.
http://picasaweb.google.com/irmosc/74JeepCJ502/photo#4994250133627535378

Yes you have lost your heat tube with the headers.

One method may be a newer 81 i think aluminum intake that is 2v with a electric heater.

It's tough to get the fuel vaporized when it's cold.

 

Did you read this thread?
http://www.earlycj5.com/forums/showthread.php?t=49985

Hard to comment on the specifics of the smog stuff without the year, displacement and whether it's a 49-states or CA model. There are places to put that in the header by your post count, and your sig. Look under "UserCP" (control panel).

Normally the distributor advance runs from ported (distributor) vacuum when warmed up and manifold vacuum when cold.

The two devices in the side of the block are called CTOs (coolant temperature override) by Jeep. They go into the coolant passages. The one with three taps controls the distributor vacuum, and the one with two controls the EGR. They are pictured in the factory service manual (FSM) for your year.

 

Which adapter did you use? Only one I have found that looks like it might fit is this one: http://store.summitracing.com/partd...839063+4294848589+4294841212+115&autoview=sku
Thats almost half the price of a used 2v manifold!

Thanks.

Brent

 

I added my specifics to my user profile. Not sure if it is 49 state or CA model though. Im in california but dont know where jeep originated from. My year is smog exempt so that is helpful. I read the linked to post, I think I am going to opt for the manual choke.

So If I understand, I need to feed two vacuum sources to the three tap CTOs and the from the CTO to the distributor. Is this what the manual is calling the "spark CTO"??

If so, then from outside to inside is Port 1, port D, port 2. The FSM doesnt state which line goes to which, but below 160 degrees 1 and D are open. Above 160 degress D and 2 are open. So from your description I would need manifold vacuum to port 1, ported vacuum to 2 and distributor to D. Correct? Unfortunately I dont see FSM diagram with those names!! And I am noob on this stuff. Carb has an EGR Spark port to the front and EGR port posterior to it. I would guess the Spark port is ported pressure and EGR is manifold pressure.. :?

As far as my PCV since there is no Charcoal Canister and EGR is disconnected should it be hooked up to the Carbs Pressure vent? The port right next to the fuel line towards the passenger side. Do I need the EGR hooked up? Smog wise doesnt matter, I just want it to run good.

Thanks for all the help!

Brent

 

Do you need to pass inspection? South Carolina did away with inspections a few years ago so almost anything goes. I removed the CTO ports and put in stops but I do run the EGR.

My adapter came with the carb. go here. This is the guy on ebay that builds the 2100 kits for jeep swaps. He has sold thousands of these and has all the parts and adapters. I think I paid $12 to add the adapter to my order. He is a wiz at these carbs.

My adapter as I remember was slightly different. I have a new intake coming to open things up a bit, but plan to still use the 2100. Best $$ for performance next to the HEI upgrade.

 

No I dont have to pass any inspection. No smog period.

Yeah, the previous owner of my jeep bypassed everything: EGR, both CTOs, removed ev canister. Now just trying to figure what I need and dont need to make it run the best.

Why did you keep your EGR? Whats the benefit?

Yeah I bought a motorcraft 2100 from that guy, but didnt realize I had a 1v intake! I guess I will shoot him an email, maybee he has an adapter on the cheap.

Which intake are you going for? Im debating between going for the clifford or just the 82+ 258 aluminum stock intake with the heater.

Thanks!

Brent

 

I don't know how to tell the difference between CA and 49-states except to compare the smog equipment to the list in the FSM. Your local inspection site will have that information somehow, but since it's a '75 you won't have the opportunity to find out.

Fine. That's what I have on my pickup, and it's ok. The automatic choke is convenient, but I plan to go to EFI eventually, so I didn't put a lot of effort into making the choke work. There's a HELP kit for the manual choke conversion that will work - you may have to make one or two brackets though.

Yes and Yes.

Yep, on the nosey.

The FSM will cover each system, one at a time. There's a table indicating which systems are used with your model and drivetrain.

Both vacuum sources are always at atmospheric pressure or lower (vacuum), caused by the pumping action of the pistons drawing in the air-fuel mixture. The EGR uses ported vacuum. The EGR CTO cuts out the EGR at below operating temp, for better cold-start drivability. The EGR also cuts out at idle, since the ported vacuum goes to zero at idle.

Not sure about which port is which on the carburetor. Ported vacuum can only come from the carburetor, but manifold vacuum can come from either the manifold fitting or the carburetor. Manifold vacuum will be strong at idle, ported vacuum will be weak (zero). The throttle plate blocks off the ported vacuum opening in the carb at idle.

I'm not sure where the bowl vent goes, but I'd guess it goes to somewhere on the air cleaner, or a low vacuum tap on the air horn of the carb. You can vent it to the atmosphere, but a source of filtered air would be best (hence the connection to the air cleaner).

The passage for the EGR exhaust gas is entirely contained within the manifolds. All the EGR valve needs is a vacuum signal. Bolt it on, connect the vacuum hose, and you have a functioning EGR.

Re whether to put the EGR back or not, it's up to you. The EGR valve mixes exhaust gas with the air-fuel charge to dilute it and reduce combustion chamber temperatures while still running a very lean mix. This reduces NOx emissions at the same time it reduces HC. Removing it will make the charge burn hotter. I'd suggest you look at your plugs after a longish highway drive - that will give you an idea of how hot the combustion is.

Glad I could help!

 

I have a Offy 4v coming and a boneyard pull 2v from 80 something, I have the exhaust manifold too as I was told you need both.

I'm going to try the Offy with the 4v as it's 50/50 on the performance from what people say. If it's too much, I'll put the 2v on. I don't want to step up to a 4v carb as I dont think the performance increase is much.

 

You need both, unless you have headers. The newer manifolds connect with an EGR pipe rather than the 4-bolt flange of the older manifolds. You can put the '77-80 2V iron manifold from a 258 FSJ on the old iron exhaust though - AFAIK the 1V and 2V early-type exhaust manifolds are the same.

The 4V will allow smaller primaries and large secondaries, which will add some performance and possibly better economy, if you can keep from using the secondaries. There are a few 4V carbs that might be suitable - Quadrajet, Motorcraft 4100, Holley 470CFM TA. The Quadrajet is a great carburetor, but can be complicated to set up well.

Pretty sure the Offy manifold will only work with the old-style exhaust or headers. You may have to trim it to clear the headers... with trimming it might work with the new-style exhaust.

 

Could I not just put the 2100 on the Offy with and adapter or is that pointless in gains over a 2V stock from the 80's?

 

Sure, if you can get the Offy and 4V-2V adapter for less than the later 2V manifold. There'll be something of a big plenum under the carb - don't really know what that will do. I expect the added volume in the manifold won't matter, since the 4V runs fine on just its primaries anyway.

From what I've read, the 2V aluminum manifold works well on these engines, and there's not much reason to go with an expensive aftermarket manifold unless you want a 4V.

 

I agree, so I'll use the Offy first as part of my experiment. I need a new gasket for the manifold to block so I have to pull it anyway.

 

The 304s had different engine colors between CA and everyone else. Blue was everyone else, I think red were CA. Did other engine models do this too?

 

Hmm. My '73 CJ-5, bought in Fullerton CA, was AMC blue metallic. The '72s may have been red - I don't remember specifically, but I don't recall any red AMC engines. The Buicks 350s were red IIRC.