Gas Mileage Tanked Bad

[Eagle]

this is what i followed when i adjusted my valves:

 

1. Disconnect the cable from the negative batter terminal.

2. if the rocker arm covers are still on the engine, refer to section 4 and remove them (section 4 just tells ya what to take off to take the covers off)

3. if the valve train components have been serviced just prior to this procedure, make sure that the components are completely reassembled.

4.rotate the crankshaft untill the nuber one piston is at top dead center (TDC) on the compression stroke. To make sure you do not mic up the TDC positions of the number one and four pistions, place your fingers on the number one rocker arms as the timing marks line up at the crankshaft pulley. If the rocker arms are not moving, the number one pistion is not at TDC. [This sentence is backwards. See below.] If they move as the timing marks line up, the number four pistion is at TDC.

5. back off the rocker arm nut untill play is felt at the pushrod, then turn it back untill all play is removed. This can be determinded by rotating the pushrod white tighting the nut. Just when drag is felt at the pushrod, all lash has been removed. Now turn the nut an additional 1 1/2 turns.

6. Adjust the number one, five, and six cylinder intake valves and the number one, two and three crankshaft valve in this position, using the method just described.

7. Rotate the crankshaft untill the number four pistion is at TDC on the compression stroke and adjust the number two, three, and four cylinder intake valves and the number four five and six cylinder exhaust valves,

8. install rocker arm covers

 

I don't know where you got these instructions, but they are wrong. The following is from the original Jeep Factory Service Manual:

 

 

 

Adjust the valves with the tappet on the base circle of the camshaft lobe in accordance with the following procedure.

 

Rotate the engine until the index on the vibration damper lines up with the 0* mark on the timing scale. The engine should also be in the No. 1 firing position. This may be determined by placing your fingers on the No. 1 rocker arms as the index on the damper approaches the 0* mark. If the valves are not moving, the engine is in the No. 1 firing position. If the valves move as the index approached the timing scale, the engine is in the No. 4 firing position and should be rotated one revolution to be at the No. 1 firing position.

 

With the engine in the No. 1 firing position, the following valves may be adjusted:

 

Exhaust - 1, 2, 3

Intake - 1, 5, 6

 

Turn out the adjusting nut until lash is felt at the push rod. Then, turn in the adjusting nut until all lash is removed. This can be determined by rotating the push rod while turning the adjusting nut. When the lash has been removed, turn the adjusting nut in 1 and 1/2 additional turns (to the center tapp0et plunger).

 

Rotate the engine one revolution until the 0* mark and the vibration damper index are again in alignment. With the engine in this position, the following valves may be adjusted:

 

Exhaust - 4, 5, 6

Intake - 2, 3, 4

 

Install rocker arm covers

 

[shelbyluvv]

Are you guys quoting the manual for a 2.8? The OP has an 86 MJ with a V6.

[yxmj]

Are you guys quoting the manual for a 2.8? The OP has an 86 MJ with a V6.

 

In his first post he says it is a 2.8 out of a 93 Sonoma

 

I am still trying to understand this part

"so i adjusted the valves again today like the haynes manual says and i lost a quarter tank of gas within 1 minute"

[gogmorgo]

 For whatever it's worth, we're talking about a pretty old gauge and sender here. Mine tends to wander around, um, a lot. 1/4 tank variation is normal unless I've been at rest for a pretty long time. While it's accurate in a vague way, and can provide a general indication of how much fuel has been used, I wouldn't trust it to measure fuel consumed in a single minute. And Redwolf's has lived a 20% longer life than mine...

[Eagle]

Are you guys quoting the manual for a 2.8? The OP has an 86 MJ with a V6.

Yes. 1986 Comanche FSM for the 2.8L V6.

 

There is no valve adjustment for the AMC engines. The rocker arm retainer nut on those is torqued down against a shoulder on the stud.