More timing questions

[poser]

I have a 84 CJ7 it has the AMC 258 i6 / 4.2l and I was wondering if anyone knows if there is anyway to check the timing gear and chain. I pulled the cap and turned the crank over by hand and it moved between 10 and 12 deg before the rotor moved is this normal or to much slack thanks.

 

[Cheepjeep85]

well the slack could be the cam gear vs the distributor gear, you can pull the valve cover and do the same sort of test by watching the valves move. but the only sure way to tell is to pull the timing cover.

 

[Sasquach]

The other way is to pull the fuel pump and then you will have a direct shot of the cam, No quotes here but have read from other sources the accepted tollerance is 10 degrees although that may be a bit much.
As cheep said checking by rotor movement is not accurate due to other factors and it's a bit of work to pull the timming cover just to check, the fuel pump is easy and accurate within reason.

 

[gert]

lol 10-12 degrees of slop can make it fun to set your timing.....IMO and my 2cents worth...timing chain $30 gaskets $10 peice of mind having a new timing chain = priceless a couple of beers and a few hours of frustration and you could have a new chain on it makes for a good weekend project

 

[poser]

Thanks for the help, the problem I'm having is I'm getting a bad fuel ping under a hard load I Have the vacuum advance unplugged and the timing set at 8 deg and then at 2deg with no real change any ideas.

 

[Sasquach]

Thanks for the help But the problem I'm having is I'm getting a bad fuel ping under a hard load I Haney the vacuum advance unplugged and the timing set at 8 deg and then at 2deg with no real change any ideas.

Spark plugs could be incorrect and too hot.
Lean carburation or vacuum leak causing a lean condition.

Does it go away with premium fuel?

 

[poser]

I'm running 91 octane I just got the jeep so I don't really know what all has been done I know it has an exhaust leak at the head so it could have a manifold leak to I will check that thanks

 

[Cheepjeep85]

what kind of carb are you running? have you done the nutter bypass? does the timing float around while you are trying to set it? if you have the factory setup, the fsm says that the initial timing should be set at 9deg btdc at 1600 rpm with the vacuum advance disconnected.

you need to fill out your vehicle info in your profile, it helps us know what you have and are working on

 

[poser]

The manual I have says the timing needs to be set at 8deg btdc at an idle where did you get that info,the motor is all stock carb and all and what does a nutter bypass do thanks for the help.

 

[Cheepjeep85]

i got the information from a factory service manual here on the forums, here's the link http://www.jeep-cj.com/docs/cj7-5/cj78-factory-service-manual-31/ this is not a haynes, or chiltons manual. check the ba-engines_general one, then start reading at page 34 then look at page 39 for your timing specs. 9 deg btdc at 1600 rpm with vacuum advance disconnected and plugged, even for the cali emissions models.

the nutter bypass takes the computer out of the equation, it allows you to manually set the carb, and timing without any input from the computer or its components like the o2 sensor. but you being in cali you might have problems with emissions.