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5.7 TBI "slightly stinky exhaust" and not as good MPG

Drivers side valve train looks the same, no noticeable difference on #3 which is only at 120 psi.

Scan tool showing no codes. Idling at 1000 rpm after 1/2 butt valve adjustment yesterday.

About to readjust all valves.
 
After valve adjustment:

#1 - Went from 195 to 215
#3 - Went from 120 to 135
#5 - Went from 190 to 200
#7 - Went from 190 to 210
#2 - Went from 200 to 210
#4 - Went from 190 to 210
#6 - Went from 60 to 60
#8 - Went from 190 to 200

All valves were 3/4 turn tight after noise, now 1/2 turn tight after noise. Only other change, oil was quart low, added a quart of ATF to see if it would free anything up.

I then added one tablespoon of oil to each cylinder, rechecked compression: All cylinders went up 30-35 psi.

I am thinking the bottom end might be OK, maybe burnt valves on #3 and #6???
 
Going to pick up my buddies nitrogen tank/regulator set up he uses for his shocks. I don't have a compressor here big enough to get me 200psi, too much of a PIA to reassemble everything to drive it to a big compressor. Figure the nitrogen tank will work fine.:shrug:
 
I know on a engine (even a healthy one) that their is a little leak past the rings that the oil will help seal. On a healthy engine what is the normal increase psi would you expect to see?
 
mysunnshine said:
I use shop air all the time.
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Yes, you have a very nice "shop", me, not so much :thumbsup:

jammer1 said:
I know on a engine (even a healthy one) that their is a little leak past the rings that the oil will help seal. On a healthy engine what is the normal increase psi would you expect to see?
Click to expand...

Not sure:shrug: My "good" cylinders and bad cylinder went up 30psi. If my engine was new maybe it would have 220-240 psi compression, so maybe around 10-15% increase :shrug:
 
#3, which was around 120psi, whistles out the intake at TDC, most probably an intake valve.

#6, which was around 60psi, fills the crank case with air at TDC, most probably rings.

Looks like long block time :eek:
 
That sucks, having to redo the valve seats would have been nicer.:banghead:
 
mysunnshine said:
Time for the LS transplant.
Click to expand...

With a 4L60E, Atlas, 1-tons, 4-linked front and rear with air shocks, full cage..................:smokin::wave:


jammer1 said:
That sucks, having to redo the valve seats would have been nicer.:banghead:
Click to expand...

Yep, valve seats would have been super:banghead:



Oh well, the engine always was a crap shoot. I had no idea on miles or compression, never checked it out, I was surprised it ran as well as it did for a little while, on about 7-1/4 cylinders:rotfl:


I am about 99% sure I am just going to swap in a new GM long block, 5.7 TBI engine. That will be the most economical, time and $$$, way to get this thing back up and running. All the rest of the powertrain has been rebuilt/new, might as well not leave the engine out of the mix:twocents:

My reasons for sticking with the TBI 5.7:

1) I have a freshly rebuilt 700R4. If I had a 4L60E, I would consider a newer/more powerful GM engine. But, I don't want to use/have to reconfigure all that TV cable stuff again. Sure it could be done, but I think my 700R4 will last longer with sub 300HP going through it:twocents:

2) I can get a complete GM long block, oil pan to valve covers, for around $1,700 delivered. Time wise, just swap on my intake and exhaust, stab it in, done.

3) My throttle body, injectors, and all of the sensors for the TBI system are brand new. New wiring harness, too.

4) In the past 3,000 miles, I have installed the following new parts on this engine: starter, water pump, ps pump, all heater/radiator hoses, idler tension bearing, AC delete pulley assembly, distributor.

5) I already have motor mounts welded in place for this engine, and I will be able to reuse all of my exhaust.

6) With a "not healthy" TBI 350, the power was good. I am sure a healthy one will feel even stronger. When this motor was running good, 16-17 mpg on the highway was normal.

7) Even though my axles are "modified" (Warn Full Float in the rear/Detroit Locker/welded tubes) (chromo 44 shafts in the front/Tru-Trac/internal mount hubs), they are still an AMC 20/Dana 30. I don't want to be playing with fire. If you know me, I drive my vehicles hard. I don't abuse them, but if I have 300+ HP, I will use it:twocents:

That's the way I am leaning now, just swap in another TBI 5.7 long block and call it a day:shrug:
 
As much as I would love to see you do an LS swap, the TBI motor sounds more reasonable.
 
mssldn said:
As much as I would love to see you do an LS swap, the TBI motor sounds more reasonable.
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Me too:drool:

LS would be sweet, but I am pretty sure I will be sticking with my "lowly" TBI:ZZZ:
 
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