I started thinking about the Jeep cutting off on me yesterday and being hard to start for the last few months. So today, I decided to give her a complete tune up. I replaced the plugs yesterday, so that much was done. I pulled the valve covers even though I couldn’t get a side cover gasket locally. The last time I adjusted the valves, I replaced the valve cover gasket with a rubber one, so I knew I could reuse it. I checked all of the valves and found that most were too tight. Most of the intakes were around .014″ and all of the exhaust were around .012″! For those of you that don’t know, the spec is .018″ intake and .016″ exhaust. I adjusted them all and cleaned the existing gaskets (the side cover gasket was cork and still in one piece on the block, so I left it in place). I put a light coat of Form a Gasket on the covers and the block (top cover). I also put a little on the PCV bell and the bolt head contact surfaces. I reassembled the rest of the parts I removed. While I was in the engine compartment, I noticed a pretty heavy drip coming from the fuel cutoff valve to rubber hose connection. I tightened the hose clamps and stopped that leak.
I fired her up (a little easier starting), and she idled quieter than before! I jumped in and took off up the driveway. I could IMMEDIATELY tell an increase in power! I got out on the highway and she ran up to 50 pretty fast – and I still had some pedal left. I drove about 5 miles down the road and came back to set the timing and carb.
I backed into the shop and shut it down. I pulled the battery cover off and opened the hood. I grabbed my spark plug adapter and installed it and hooked up the timing light on #1. I also hooked up the vacuum gauge to the tee under the carb and loosened the distributor. I fired her back up and checked the timing – it was around 10 deg BTDC and the vacuum was about 14. I adjusted the distributor until I got my highest vacuum reading of 16. The timing was showing around 5 deg BTDC at that point. I adjusted the carb, but the needle adjustment didn’t do much on the lean side – so I just adjusted it for best acceleration.
I unhooked everything and took another test drive. Power was slightly down, but the hesitation when you blip the throttle and the miss at idle are all but gone. I was able to cruise at 50 without sounding like she was going to come apart, and hit 58 a time or two during the run!
When I got back to the shop, I checked for leaks one last time – everything looked and ran good, but it was a little noisier when it warmed up.