new engine help

[ltdanyj]

New engine is in the jeep. stats are:

'72 258 6 cylinder
.060 overbore
MC2150 carb
HEI distributor
Timing set to 10*BTDC
plugs gapped to .050

The engine has a miss that is more prevalent on the rear three cylinders. Tonight, I tried dropping the gap to .040... It got a little better, but the miss is still bad enough to make me not wanna drive it. I also noticed that the exhaust is glowing after the cat... Only noticed this at night however...

I'm going to tackle this thing again tomorrow, but I'm looking for any tips or ideas you guys might have....

Dan

[Stowe63]

You are just running REALLY lean.


You are going to need a new cat for sure though.

[Stowe63]

Since I cant be there to help you out.. I hope I can do some internet research for you!! The first thing I had to remember is that I have search 1972 AMC 258... something I forgot about bro... I hope this helps!!

The 258 used in '87-'90 Wrangler YJs uses a computer controlled Carter BBD. It is very simlar to the 258 used in '82-'86 CJs, but performance suffers due to emmission controls.

AMC 258 I6
Bore x Stroke 3.75" x 3.90"
Displacement 258 (4.2L)
Compression Ratio 9.2:1
Horsepower (net) 112@3200
Torque (net) 210@2000
Main Bearings 7
Valve Configuration OHV
Fuel 2bbl Carter BBD


The 258 used in '82-'86 CJs used a computer controled Carter BBD. The computer controls mixture based on an O2 sensor and other sensors.

AMC 258 I6
Bore x Stroke 3.75" x 3.90"
Displacement 258 (4.2L)
Compression Ratio 9.2:1
Horsepower (net) 115@3200
Torque (net) 210@1800
Main Bearings 7
Valve Configuration OHV
Fuel 2bbl Carter BBD


The 258 used in '79-'81 CJs, some used a 1bbl carb and some used a 2bbl carb.

AMC 258 I6
Bore x Stroke 3.75" x 3.90"
Displacement 258 (4.2L)
Compression Ratio 8.3:1
Horsepower (net) 110@3500
Torque (net) 195@2000
Main Bearings 7
Valve Configuration OHV
Fuel 1bbl and 2bbl


The 258 used in '72-'78 CJs, J-series pickups, and Wagoneers, some used a 1bbl carb and lower compression than later 258s.

AMC 258 I6
Bore x Stroke 3.75" x 3.90"
Displacement 258 (4.2L)
Compression Ratio 8.0:1
Horsepower (net) 110@3500
Torque (net) 195@2000
Main Bearings 7
Valve Configuration OHV
Fuel 1bbl


The 258 was introduced in 1971 as the standard engine in J-series pickups and Wagoneers.

AMC 258 I6
Bore x Stroke 3.75" x 3.90"
Displacement 258 (4.2L)
Compression Ratio 8.5:1
Horsepower (gross) 150@3800
Torque (gross) 240@1800
Main Bearings 7
Valve Configuration OHV
Fuel 1bbl Carter or Holley

MODEL NUMBER BD-220, BG-220 BD-240, BG-241 BD-264, BG-265
Number of cylinders: 6..... .6....... 6
Bore (inches) 3-9/16............ 3-9/16............... 3-11/16
Displacement (cubic inches) 220.5 ...............240.3............... 264.33
Compression ratio 7.5.................. 7.5.................. 7.5
Brake horsepower (max.) 112.5 @ 3800 rpm................ 140.8 @ 3800 rpm ......................153.5 @ 3800 rpm
Brake horsepower (net) 91.9 @ 3400 rpm ..............................115.1 @ 3600 rpm.......................... 130.3 @ 3600 rpm
Torque (max) (ft.lbs.) 194.4 @ 2000 rpm .......................223.5 @ 2000 rpm .............................248.0 @ 2000 rpm
Torque (net) (ft.lbs.) 178.0 @ 1200 rpm ..................................211.0 @ 1400 -1600 rpm ......................236.0 @ 1200 rpm
Weight, bare (lbs.) 549 .................570 ............................600
Weight, with standard accessories (lbs.) 635...................... 656 ........................687
Valve tappet clearance (hot)
(intake and exhaust) (inches) .024-.026 ..................024-.026 ......................024-.026
Firing order 1-5-3-6-2-4 .....................1-5-3-6-2-4 ..............1-5-3-6-2-4
Spark plug gap (inches) .028-.033 ..................028-.033.................. .028-.033
Distribuor points gap New points (inches) .019 .............019 ..................019
Reset (inches) .016 ...............016 ..................016
Cam angle (degrees of dwell) 28°- 35° ...............28°- 35° ...........28°- 35°
Initial timing setting 4° B.T.D.C.............. 4° B.T.D.C. ..............4° B.T.D.C.
Idle speed range (RPM) 350-400 ..........350-400 3...........50-400 350-400
Maximum recommended speed (RPM) 3600,,,,,,,,, 3400 3400

The engine serial number is stamped on the block - right side, upper front corner

[H2_RECOVERY]

first thing to check is firing order. make sure you are using thw 4.2 liter not the 4.0 liter firing order. second look for vacum leaks like hoses and intake gaskets.

[CCrew]

first thing to check is firing order. make sure you are using thw 4.2 liter not the 4.0 liter firing order. second look for vacum leaks like hoses and intake gaskets.

I'll second this, have also seen it with cracked/carbon tracked/wet distributor caps.

-R

[ltdanyj]

first thing to check is firing order. make sure you are using thw 4.2 liter not the 4.0 liter firing order. second look for vacum leaks like hoses and intake gaskets.

Okay.... Do you know the firing order for the two different engines? Everywhere I look, I'm being told that the firing order is the same.... This includes Alldata....

[H2_RECOVERY]

I might be wrong. I thought that there was 2 for the 4.2 and the 4.0. what i am finding is 153624 going clockwise on the distributor

[MUDBUG]

I could check this afternoon if you want...

[Stowe63]

Everything I have read about the glowing cat is that you are running super lean and the cat is burning the extra fuel off.

As far as I know all 258's and 242's have the same firing order... nothing that I have come across makes me believe other wise.

You are sure you have all of your sensors plugged in? Im not sure what they had in '72 (I wasnt around then :wink: ). Distributor is in the correct location? (Not retared? :lol: ).

Also... In the info that I C&P above says your gap should be .028-.033

[MUDBUG]

Also... In the info that I C&P above says your gap should be .028-.033

I know that for the HEI distributor the gap is increased from the stock setting. Even my TFI gaps the plugs at .045. From what i've read for HEI it should be .045 to .050. (that comes from the CRT Performance website that sells HEI kits for 258's)

[Stowe63]

Also... In the info that I C&P above says your gap should be .028-.033

I know that for the HEI distributor the gap is increased from the stock setting. Even my TFI gaps the plugs at .045. From what i've read for HEI it should be .045 to .050. (that comes from the CRT Performance website that sells HEI kits for 258's)

See... its the fancy stuff that will get you every time! :P

[ltdanyj]

OK.... I just talked with the guy I bought the engine from. Firing order should be the same from '49 on up.... One thing he said he did by accident was install the dizzy 180 out.... Shockingly, it ran... just not well... kinda like it's running now!! LOL..... I could SWEAR that I've installed it properly, but tonight, I'm going to put in 6 new plugs, and re-install the distributor, backwards... hehe... We'll see what happens....

Dan

[MUDBUG]

It's pretty easy to get the engine at top dead center on #1 cylinder and set the distributor at #1. It might be better to just verify that it's installed correctly rather than trying it at 180 out...although I suppose it wouldn't anything...lol