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post #1 of (permalink) Old 12-30-2002, 06:50 PM
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Intake woes! Leak or lean carb.?

My '80 CJ-7 304 engine is acting up again. The headers turn "glowing orange" 5-10 minutes after start up.This problem has occurred several times since my rebuild. Rebuild was 2 years ago, but mileage is less than 800 miles. At rebuild I went with an Edelbrock Performer intake, Edelbrock Performer Carb (500 cfm), and Competition Cam. The cam is not radical. Just one step up from stock. This engine has passed the sniffer test one year, and blown the needle through the roof the next. Just finished another intake gasket replacement. Still glowing orange!
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post #2 of (permalink) Old 12-30-2002, 06:57 PM
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Re: Intake woes! Leak or lean carb.?

what did the numbers look like if you still have the prior year's pass sheet and the recent failure?
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post #3 of (permalink) Old 12-30-2002, 07:32 PM
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Re: Intake woes! Leak or lean carb.?

The Jeep paassed in'99 with HC (ppm) 0126, CO%o.87, and CO2 %14.3. It failed in '00 w/ HC(ppm) 230, CO% 7.76, and CO2 %9.9. I think this was due to old gas and cold engine condition. I changed fluids,ran two tanks of fuel thruogh it and leaned out the carb a touch. It passed with HC9ppm of 027, CO% 0.00, CO2% 14.3. The Jeep was running fine with no "glowing exhaust" before I started A "frame off". Now it is acting up again. I have in-frame headers and dual exhaust w/dual cats and flowmasters.
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post #4 of (permalink) Old 12-30-2002, 10:27 PM
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Re: Intake woes! Leak or lean carb.?

glowing headers are a good thing. Follow this link and click on the dyno test one(3rd down i think).......

Lingenfelter

[img]images/graemlins/burnout.gif[/img]

seriously though, those numbers match up with the prior ones for the most part. what did you change in the frame off? what kind of headers are you running? long or short tube? tube diameter? whats your temp gauge reading when it does this?

[img]images/graemlins/givemebeer.gif[/img]
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post #5 of (permalink) Old 12-31-2002, 05:16 AM
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Re: Intake woes! Leak or lean carb.?

Thanks for the response Gragehead! My frame off was for boby work and paint. The idea was to do drivetrain first then body. I just can't get the engine right. The only thing that happened to the engine during this "rest" period was that the frame and engine sat out in the sun during July in Wilmington,NC. The headers are Hedman in-frame with the TLC coating. Don't waste your money on the coated headers by the way! They rust too! I'll check on diameter, but they're just the normal headers in a box most people sell. I had the same headers with old stock manifold/carb. combo with no problems.(I can't believe I'm saying this, but I'm thinking of going back stock.) Last night the cats started to glow. First time I've seen that. I shut it down immediately. Cats are on cause I live in Raleigh. My carb tuning was to get it running the best and as clean as I could get it. The temp. gauge never gets hot (stock gauge). I usually shut everything down immediately. Engine was bored over.030. The engine rebuild was local and not as smooth as I'd hoped. Will consider other alternatives next time. But when she runs she runs like a scolded dog!
post #6 of (permalink) Old 12-31-2002, 07:19 AM
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Re: Intake woes! Leak or lean carb.?

The exhaust glowing obviously is excess fuel burning in the
headder and cat. Lean misfire can cause that, or too much
fuel.

Sounds too rich - but those numbers aren't showing it, possibly
because the cat's doing a great job burning off the excess.
The sniffer test is behind the cat, so the engine can be
really dirty and the cat can compensate for it.
Kinda like running behind the horse with a shovel.

I'd bet if you disabled the cat you'd see it's really rich.
If it was too lean, the heat is developed in the engine, not
the exhaust, so your temp gauge should show it more, and
you'd notice poor performance too.
If it was one cylinder misfiring causing excess fuel in the
exhaust, you'd be complaining of the misfire as well.

Follow procedures for rich condition.
And - try the Mexican tune-up - could be a spider or bug
took up residence in the carb - air bleed or emulsion tubes.
Rev to 2500-3000, choke the carb off completely with your
hand until it dies. Restart, do it again.
The high vacuum created by choking it like that can suck
that spider out and any other trash or water that may have
collected.
It's not a cure-all, but sometimes it works, fast, cheap,
and it's a good trail fix.

Let us know how it turns out.
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post #7 of (permalink) Old 01-12-2003, 04:41 PM
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Re: Intake woes! Leak or lean carb.?

Update on my Jeep. It's been a long battle that has tested patience and my mechanical ego. My 304 was glowing orange at the headers! I checked manifold vacuem leaks, installed new carb. gaskets, new metering rods and even checked the bridged rocker arms for correct torque on the bolts. Disconnected the dual exhaust(2 cats and flowmasters) yesterday. No orange glow!! Obviously a restricted exhaust. Removed exhaust system today. Not easy! I cut the pipe in front of the cat. It looked fine! I could see the honeycomb screen. No appearance of meltdown. I did find a terrible welding/fitting job at the reducer behind the header! Instead of butting the reducer and exhaust pipe together and welding, they jammed the pipe up into the reducer. This creates a less than ideal flow. Since my header problem showed up almost immediatly after the engine rebuild and new exhaust I am wandering if this can be the problem? Does anyone think so? I'll still check the cats and maybe "modify". Anyone try the Pacesetter exhaust kit sold in 4WD Hardware? I know it is actually for a CJ-5.
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