Backfires when transmission put in gear

GEKKO77CJ5

MEMBER
1977 JEEP CJ5
4.2L
6 CYL
4WD
MANUAL
9,999 MILES

Recently got this vehicle on trade, when I got it it seemed to run fine, granted a bit sluggish in my opinion but otherwise I had no complaints on the first outing. Decided to do a bit of a time up, new plugs, wires, fresh blood and filter and what I thought to be a upgrade to a hei distributor. Also replaced the water pump thermostat and put a nee timing chain and gears in. Hasn't been right since.
Got it to run beautifully at idle without a load set at 9° advanced. But as soon as you put it into gear the backfiring begins. I'm at a loss and developing a pretty serious bald spot due to all the head scratching. Any and all assistance and suggestions are greatly appreciated.

6 Replies

CJ MEDEVAC

MECHANIC
11,005 POSTS

Do you have a vacuum gauge?

Dwell/Tach meter?

Timing light?

Did you fully understand how to install your distributor correctly, or did you sort of wing it?

Unless you are baja racing and such, the HEI was more of a bragging thing than an improvement.

My newer one is a 1977 also, the best ignition improvement I did was to rid it of the Prestolite system and upgrade to Motorcraft, which arrived in the 1979 CJ.

Have you looked for vacuum leaks or loose or cracked hoses?

Answers? Any more preliminary information?

The Medic

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Monday, March 25th, 2019 AT 7:13 PM

GEKKO77CJ5

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4 POSTS

A timing light I've got the rest I'm lacking. As to vacuum leaks I'm sure theres probably tons I haven't found yet. There's wires and vacuum lines running all over under the lid and I hadn't had the time to track them all yet. As to actually know what I'm doing, I usually know just enough to get me into trouble.

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Monday, March 25th, 2019 AT 7:18 PM

GEKKO77CJ5

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A few pictures I thought I'd snag to attempt to show what it's got going on under there. My apologies for the horrid lighting. I'll try to get more tomorrow when the suns up if needed.

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Monday, March 25th, 2019 AT 7:34 PM

CJ MEDEVAC

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See you tomorrow.

I like that color too, I do kind of keep it out of sight.

The Medic

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Monday, March 25th, 2019 AT 7:54 PM

GEKKO77CJ5

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Nice! Really digging the air horn setup been trying to talk the wife into a set. I appreciate the feedback thus far, thanks for your time and goodnight.

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Monday, March 25th, 2019 AT 7:57 PM

CJ MEDEVAC

MECHANIC
11,005 POSTS

Up and at it!

I showed my girlfriend (now wife of 12 years) the horn system online. I said I would get it one day. It was on the verge of $500.00.

Presto! A week later she presented to me!

(I'm just that sweet of a guy!)

After installing it and testing it out, I deemed it almost perfect!

We went to the mall. As we sat in my awesome Jeep, she asked why did I want it.

I told her with that horn, I could be "in charge" of any traffic situation. I could also "control" people too.

About that time we looked up and saw this mid-20s woman walking from right to left towards the mall.

I actuated my new train horn and held it for about fifteen seconds as the woman was perfectly centered in front of the Jeep.

It was almost horror flick material. The woman remained in a three foot square and danced about as if she was being electrocuted the whole fifteen seconds!

(Girlfriend/now wife was close to being startled the same way)

When I turned loose she crumpled to the ground, then on her knees she "ran/ half crawled" about ten feet until she finally got to her feet and ran to the mall!

I told my girlfriend/now wife, "now that's just one example why I had to have the horn".

The Medic

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