Read about everybody?s milage and I?m getting a bit below your average. I get 14 mpg, part town part highway (driving economically). The worst is that my engine feels really tired...It won?t rev out in the high gears and feels really low on both effect and torque. Especially in forth and fifth gear, it won?t go faster than 70 mph<img src="/forums/images/graemlins/sleeping.gif" alt="" /> in fourth and less in fifth...won?t rev above 3000 rpm in fourth...Other that that it runs great:) I rebuilt the whole engine last summer and I've only put maybe 3000 miles on it. The truck has 5 spd manual, stock rear axle and sits on BFG A/T 31" (31" tires on 15" rims should equal the same roll diameter as stock tires on 16", right?).
I just changed the O2 sensor and fixed an exhaust leakage near that sensor as well. Feels like the combustion is a little better now with no leakage and new O2 sensor, but still no speed. New plugs, air filter and timing @ 12 dgrs with shorted connectors. Thankful for any thoughts <img src="/forums/images/graemlins/cheers.gif" alt="" />

the timing should be at 12* without shorting, or 5* with shorting.

I?ll change that tomorrow...used to be 5 dgrs but set it back a bit today to maybe get some more power. But I don't think that?s the problem...I took a couple of short drives with different timings today and no notable differences.

Set the timing @ 5* with connectors shorted, no difference between that and 12*...
I also made a compression test;
135-140 psi on all cylinders except 4th where I got 120 psi. It?s a bit harder to get a good reading on 4th due to lack of space but I re-did it a couple of times w/ same result. I put some oil on the piston but no increase...
Valves timed according to specifications last summer.

readjust the valves.
another thing, do you have a catalytic converter? It may be plugged up. Look and see if there is a good exhaust stream coming out of the pipe when the engine revs up.
DAnny

I'll take a look at the valves next weekend...
And the cat seems to be OK...nice flow coming out of the exhaust...but I've been thinking of fitting a pipe instead of the cat to see if there?s any difference. And just have the cat in when I do the emissions test.

Just put a new cat in, also took a ride w/o the cat and still no increase in power <img src="/forums/images/graemlins/confused.gif" alt="" /> Maybe a little bit better throttle respons. The old cat had 20k / 15 years on it so it didn?t hurt to get a new anyway...must be the bad compression in the 4th cylinder...will check up on that later this week.

I wonder why the compression is so low considering you just rebuilt it recently?

one can only speculate in that:) Could be that one of the valves aren?t seated properly in the head due to not enough grinding...gonna check and see if the clearance has changed, which I doubt... <img src="/forums/images/graemlins/confused.gif" alt="" />

I understand that you have lower compression in the 4'th cylinder, but I was referring to the overall low compression in all the cylinders. To my understanding these cylinders produce around 170 psi new, and even after ALOT of use they still seem to hold very well at 150 or better. That hasn't been my experience (because I don't personally have that much experiece) but that of others based upon all the reading and research on this forum and others.

I should add that my lone pickup with a 22re ('94 with 143,000 miles) still had 150-165 psi in all cylinders before my recent top-end rebuild. #4 was at 150, and all the others were 160 or better.