Did I finally figure out what's wrong with my Stroker??

[Billygoat]

I have been working on my stroker project for almost 6 years now. It's in a completely rebuilt CJ7, and everything is new down to the last bolt. My main dilemma: the exhaust manifold and catalytic converter glow orange after driving or offroading, and the power is not what it should be (The Jeep has 4.56 gears, 35" tires, and won't go faster than 60-65 on flat ground unless I cruise at 3500-4000 rpm)...also the idle could be smoother and the engine pops/backfires out the exhaust occasionally when engine braking. The system is a 1994 OBDI with Hesco ECU, adjustable fuel pressure regulator, rebuilt Ford Taurus 24lb injectors, dished pistons and decked block ~9.2 CR 4.6L with a Crane Cam (it's an old project), plate and fin type oil cooler, flowkooler water pump, dual electric fans, and wideband O2 and AFR gauge. The cam was Crane's "truck" cam, and they said was the largest that would work with the factory ecu. The AFR is reading lean, and I am trying to tweak it with an adjustable MAP sensor voltage thingy that I made via Dino's instructions.
My hypothesis:
1) The cam is too aggressive, and I should retard it 4 degrees with my Cloyes double roller timing set
2) The exhaust is too restrictive. I moved during the project, and decided to have a shop do the last few installations on the Jeep while I moved so I could drive it to my new home instead of paying to have it towed. BIG MISTAKE. The shop I took it to must have had dollar signs in their eyes when I told them over the phone what it was, and they took me to the cleaners. Not an honest shop at all. They gave it back to me with a non-functional temp gauge and told me not to worry about the temp on a NEW engine. I later realized that this was because the engine was overheating, and when I relocated the temp sending unit to the thermostat housing the temp gauge went back to normal. They also didn't understand why I wanted to change the oil in my NEW engine before 3,000 miles (they wanted me to destroy my new engine so I would pay them to install a new new one?). Well enough ranting--this shop had yet another shop install custom exhaust, and just the other day a light bulb turned on in my head and I went and measured the tailpipe...it is 2" ID! Will 2" ID exhaust cause overheating problems? Or is my problem most likely just related to an AFR and camshaft timing issue?

I have been trying to get this engine to run right for almost two years now with only slight improvements. I put 1,500 miles on it because I got impatient, and I melted the driver side motor mount AND the hydraulic clutch line (I later switched to braided SS). If anyone has any advice then please, please chime in. I can't keep dumping money into this thing. I know there are piggyback solutions for the AFR, but if retarding the camshaft would be an equally effective solution I would rather do that. Also I need to know if I should call up this shop and try (probably unsuccessfully) to make them redo the exhaust (They knew the engine was a 4.6L stroker and deserved better than a 4-banger exhaust). They also insisted on installing a Hesco non-smog legal air filter that I got dinged for by the referee and had to replace....GRRRRR!

[Billygoat]

When I say the AFR is lean, I mean slightly lean, as in 14.8-15:1 at idle...

[CobraMarty]

Maybe a clogged cat converter. 2" ID is small. I would change it all out from the header back.

[gradon]

2.5" from header to tail is the way to go.

[gonridnu]

The things that stuck out in my mind are the glowing headers and exhaust and the melted engine mount. If you are seeing the glow outside in the daylight it is lean if inside in a dark shop maybe not. The decel pop could also be "lean pop". You could have incorrect ignition timing as well. it's easy to check with a dial back gun. The heat required to melt a motor mount indicates it is the exhaust system and not the engine cooling system that is producing that kind of temperature.

I honestly don't think a smallish exhaust is going to do this. A clogged converter maybe. If the exhaust size is restrictive it will run fine at lower RPM's and in upper rpm's it will start to fall off as the engine begins to pump more air than the exhaust can handle.

The heat makes me think it is a lean condition and if it is lean at idle what is it doing under load?

[Cheromaniac]

A glowing header is usually caused by either a lean condition or over-retarded ignition timing. I have a feeling that you might need to index your distributor so check that out and see.

[tequila mike]

If your cam is such that your exhaust valves are open at the wrong time (Late in the cycle), it might explain your problems.
Could be cam duration maybe and or timming?
Sounds like your cat is cooked and likely melted inside.
I dont think a smaller exhaust would cause it to over heat, just slower to get up to speed.
Afr wont tell you much at idle.
You could pull the valve cover and determine when the exhaust valve is closing, compair it to TDC timming mark.
You should be able to figure out where it should be close to.

[CobraMarty]

I would cut the down/front pipe somewhere convient and add a section of straight pipe to side exit and take it for a gentle/quiet ride. You can always try and blow thru the rest of the cut off exhaust, that would be kinda wierd though. Things are usually quite simple.

[SilverXJ]

The 2" exhaust won't cause your issues. As others have said, ignition timing, cam timing, lean or injector timing. Did you degree the cam in?

[Billygoat]

The distributor has been indexed probably ten times with no changes. I have even indexed it wrong on purpose just to see what the symptoms are, and it is indexed correctly. The cam timing is at factory settings (unless I messed it up when I put the engine together, which is unlikely but always a possibility). There is enough exhaust coming out the tailpipe to blow my hair back at idle, and the cat has about 1k miles on it. One thing I noticed is that the afr jumps around when I let off the throttle--the gauge jumps to really lean for a fraction of a second, then goes to really rich, like 12:1 before it levels back out around 14.6-15.2 at idle. The cam is comparable to the new Crane Cams H-260-2 so it really isn't all that big... http://www.cranecams.com/40-41.pdf The manifold glows orange, but I have realized that it is hard to notice unless it is in a dark garage or in the shade. Could it be an exhaust leak causing erratic afr when I let off the idle?

[SilverXJ]

An exhaust leak could cause the afr jump off throttle, but it is normal to see if go lean, then a bit rich, don't know how rich it should go though. Just because you installed the cam dot to dot doesn't mean it is ground correctly as well as the timing set could be off or you are a tooth off. Getting a tooth off is easy to do with a double roller with the smaller links.

[Billygoat]

I'm thinking I might just need to pull the timing cover and check to see if I am off a tooth...I toyed around with the idea of moving the CPS, but that only changes the ignition timing and won't help if the valve timing is off. What really throws me off is that the Jeep passed smog with no problems--I guess a lean issue or a new cat would help a lot with that though. Now to go buy a gasket set and pull the radiator...and I'm supposed to do a Rubicon run next week...

[Billygoat]

It has been a looong night, but I checked the timing chain, and the marks line up perfectly. I also managed to pull the broken piece of harmonic balancer puller out of the snout of the crankshaft with an ez-out without damaging the threads--I only had to remove the grill to get to it! I am thinking that while I have the Jeep apart I'll remove the '99 intake and install the original '94 intake manifold (the smog guys here won't pass the Jeep unless it has the original intake for that engine) and in doing so eliminate any possible manifold leaks via a new Mopar gasket. I have read that sometimes the newer intakes can actually hurt performance--I think Petersen's 4 Wheel and Offroad did a dyno test comparing the manifolds, but I may be wrong. If anyone has any advice about the manifolds feel free to chime in. Oh, and I did a compression test with a gauge I rented from an auto parts store--I got 89 psi on each cylinder. I really hope that gauge is just way, way out of calibration (the block was bored .030, the pistons are .030, the rings are .030, the cylinders were honed, the head was professionally rebuilt, I don't see how compression would be low). So the distributor is indexed, the timing chain is set perfectly at factory settings, the exhaust seems to have good flow and the engine actually pulls pretty hard in higher rpms. It hesitates when I'm poking around under the hood and pull the throttle body from idle to full throttle all at once though.

[SilverXJ]

Just because the timing chain is dot to dot doesn't mean jack.

[Cheromaniac]

I am thinking that while I have the Jeep apart I'll remove the '99 intake and install the original '94 intake manifold (the smog guys here won't pass the Jeep unless it has the original intake for that engine) and in doing so eliminate any possible manifold leaks via a new Mopar gasket. I have read that sometimes the newer intakes can actually hurt performance

No, the newer intake doesn't hurt performance. In fact the opposite is true but to a small degree. The newer intake does, however, provide a more evenly balanced airflow to the cylinders resulting in slightly better gas mileage and emissions. It therefore seems retarded that the smog Gestapo won't pass the Jeep unless it has the old inferior intake. Maybe you should tell those idiots that the newer intake is a factory part and not an aftermarket item.