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bluegrass107 07-04-2007 03:04 PM

Timing chain Questions
I've got a 90 yj w/ I6 258 manual- and I was having problems starting. I noticed that I wasn't getting spark or fuel and began looking at the timing chain. When I opened up the cover the camshaft sprocket was completely loose cause the bolt had come off. With that loose everything is out of position. So now my unknowns are... do I set the crank on the intake rotation or the exhaust rotation? Do I need to set the cam at 1 oclock like my book says or is there a phase issue there too? I searched the threads but no data any help would be appreciated.

Scotty355 07-04-2007 07:14 PM

If the sprockets came off while the engine was running you may have more issues like bent valves. I would try putting everything in time and try starting it, you might luck out and not have any further damage..

Usually the crank is set so that #1 cylinder piston is at top dead center and align the marks on the camshaft and crank sprockets.

I never worked on a 258 but that is usually the standard on most american pushrod engines.

bluegrass107 07-05-2007 09:12 AM

Thanks for the reply and thats all good but my crank has turned so I don't know where in its revolution it is, and thats a problem. I know that I can feel for air flow with my no. 1 spark plug out. What I don't know is should the crank be on the intake or exhaust phase of the revolution. Any info would be good--THX

Scotty355 07-05-2007 12:29 PM

The camshaft is what determines if it is intake or exhaust, if you put the timing mark on the balancer at 0. the #1 piston will be at TDC and then your timingchain marks will line up or be 180 out, if 180 out turn the motor 1 revolution and they should now line up, when marks on sprockets are lined up now set the distributor rotor pointing at #1 spark plug wire as the book says.
I am at work now and can't look up any diagrams but when I get home I'll try to find something for ya.

bluegrass107 07-05-2007 01:30 PM

Your timing is great cause I've just pulled everything back apart so I'm at that point. Thanks Bro

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