Yes I'm going to do the plenum gasket as soon as the parts are in. Is there really anything I can do for #7 or #8 cylinders with the lower compression? Or is it really anything to worry about? I also did the magnet test on the plenum pan and it's not aluminum.

 

I really don't think you have anything to worry about. I had a misfire on my #8 cylinder because of a blown plenum. It covered and soaked my spark plug in oil. Get some new spark plugs and give your beast a tune up while you do the plenum. Replace the cap and rotor while you are in there because it's super easy after you take the intake off.

 

10-4. Already have the new wires/cap/rotor sitting here. I was planning on waiting until I did the plenum lol. I went ahead and put the new plugs in today. Probably a mistake but the ones I pulled out looked so pathetic I had to go ahead and put them in. What else should I do while doing the plenum? Water pump? It apparantly already has a 180* stat in it but I will likely replace it also. Need to replace 2 freeze plugs also. Might as well do that while it's apart.

 

Actually, your numbers look REALLY good.... Most auto manufacturers allow for as much as 25% difference from high to low on compression, and 100 PSI as a minimum value.... So, you are doing really well.

Do the plenum, the tuneup, replace the front O2 sensor, and if you are feeling really froggy, hollow out the cat... (if you can get away with that where you are, if not, get a magnaflow hi-flow cat, WITH the Y-pipe. You WILL notice the difference.)

If you have the scratch, also do your water pump, and timing set while you have the intake out of the way. It's only a few more bolts, about half of which, need to come off to do the pump anyway. It is never going to be any more convenient than while you are doing the plenum.

I did my plenum, and a week later, I developed a coolant leak at the timing cover..... so, I got to do part of the job twice. I was absolutely AMAZED at what a difference doing the timing set made. That was the ONLY change, aside from the water pump.... and the engine ran a HELL of a lot better.

 

Water pumps are pretty cheap for these trucks too. I think mine was around $40. I replaced mine when I did my plenum just for kicks and giggles since I had to remove the ac unit, alternator, and accessory bracket.

Another thing to check is your valve cover bolts. Some of mine were hand tight and noticed I had a few leaks.

 

Thanks HeyYou that makes me feel a little better about the compression . I always heard no more than 10% and couldn't really find much info anywhere on it. I had the cat taken off a few weeks ago when they ran the duals. Eventually after she's 100% mechanically I'll get some of the cheap e-bay headers for it and have bigger pipe ran from the headers. I'll go ahead and do the water pump and timing set since I'll be that far into it. I'd hate to have to tear it all apart to do it again!

 

Yeah, demonstrate some supreme intelligence, and learn from SOMEONE ELSES mistake.

Works for me.