Didn't have time to price any longblocks this week so will pick up next week. I know i said i wouldn't do any further trouble shooting, but, i did have a buddy of mine loan me his CO2 leak detector to determine if i had leak across the head gaskets; these tests were negative.

I also used a fiberscope to look inside each cylinder. As it was getting dark, i didn't have time to rotate the engine to get a full view of the cylinder and/or valve operation; also, this scope is a dinosaur and doesn't have the articulation necessary to get a thorough view of everything. To be short, i didn't see anything that jumped out at me, in the way of burnt valves, melted pistons or excessive cylinder wear; combustion appears uniform across each cylinder. Also, very little carbon deposits seen on pistons. Don't know if the seafoam treatment i performed last week cleaned them up, or, if any was ever present to begin with; this would go for the valve faces too.

Gonna put plugs back in and however meaningless it may seem, run to parts house and put a can of restore in. Worst case, i'll be out of $10. James

 

I just revisited your #8 post, related to the compression tests.

Those wet/dry test done are showing some very close readings. I just can't believe that you need to sink that kind of money and labor into a Longblock. That of course would resolve any wear issues, and basically give you a complete rebuild.

Again, I'm going to stick my neck out a little here, and say that what you really need is (only) a Valve Job.

 

You never want to tow anything in overdrive especially something that's 5000lbs...

 

SW, since i took those compression readings last week, I was of the same opinion as you (valve job). However, I'm afraid with 152K miles on the short bock, combined with the new found compression from new/rebuilt heads, those rings may be short-lived. As much as i want to save some money and go with heads only, i'm a little hesitant as i believe i will be back under the hood sooner than i'd like. I guess i could order heads initially and tear the engine down to the block; at that point, I could inspect/mic the cylinders and use feeler gauge to check gap/tightness to determine if longblock is the route.

84, I agree that on steep grades/inclines towing out of OD will be necessary. However, on flat roads (with 4L80 tranny), I would think my setup should be capable of towing in OD. I know there is wind drag to consider, but, this isn't much weight. Hell, maybe driving that Cummins for the past 10 years has spoiled me and I am expecting too much from this sbc. I appreciate your opinions and welcome all recommendations, keep em coming! To be continued....

 

I agree, based on what i have read/studied and what little i know of this Chevy tranny.

 

I applaud you for considering a "Turn Key" job.
Do it once, right, and it's over with.

I certainly agree with heavier Tows opting for 3rd may be better.
However, given either Transmission and the Load, IF one finds that there no excessive downshifting, then I see no reason not to take advantage of the lower RPM, and possible increase in MPG. Several factors involved in that decision, and I don't want to be the one that says you "must" use 3rd only.

One thing suggests the selection of OD...
The way that GM has a tendency to "control" what you do, IF using OD when Towing was really harmful, they'd find a way to lock it out.

BTW:
The 4L60E with (Electronic) Tow Mode, permits the use of OD when in Tow Mode.
It is, considering the Shift Point Retasking, limited to higher speeds (aprox 50+ MPH)

 

Alright, after driving approximately 70 miles with a treatment of Restore in the crankcase, i rechecked the compression last night. The strange thing is, it seems i lost quite abit compression in #1,3 and 5 cylinders. I'm thinking it was gauge related, as this tester was new, and, these were the first three cylinders i tested back on July 19th. Regardless, looking at these numbers, the compression across the engine is fairly uniform, and, would indicate the treatment really hasn't affected (improved) the compression numbers from my initial testing.

Cylinder #1 125-130psi (dry) 135-140psi (wet)
#3 125+- (dry) 130-135psi (wet)
#5 115+- (dry) 120-125psi (wet)
#7 110-115psi (dry) 120-125psi (wet)
#2 105psi (dry) 125psi (wet)
#4 105-110psi (dry) 125-130psi (wet)
#6 105-110psi (dry) 125-130psi (wet)
#8 110+- (dry) 125-130psi (wet)

Would this not be further evidence the valves are likely the culprit? Regardless, if/when i have the time this weekend, will try out my new cylinder leakage tester narrow it down; will post back when i learn more. thanks

 

Those readings look pretty normal to me...
I see nothing below 100#, and...
wet increases are reasonably consistent.

So yes, valves.

 

10-4. If weather and my work schedule permit, hope to measure cylinder leak down this week to confirm. Also, if i can get my hands on a psi gauge, and, a schraeder valve exists somewhere on the fuel supply, will check the fuel pressure too; the shop i took this truck to said pressures were good but not sure if i believe this 100%. Also, will be pulling the pan on the tranny at some point and replace filter; will need to purchase a Chilton/Haynes to see if there are any band adjustments i can perform while in there. To be continued....

Forgot to mention this earlier. I pulled all four oxygen sensors late saturday. I didn't test the wiring or anything and basically just cleaned them (emery cloth and solvent) and reinstalled. I realized one of the sensors was different from the other three; this would be the one upstream of the cat on the driverside. The shield surrounding the element had small perforations in it; the other three had slits, resembling louvers. I didn't think of taking a photo of it until after i had it re-installed, but, took a photo of the other three; it is attached below. Also, i replaced the TPS. Of course, these efforts did not improve anything. thanks

 

Really doubt if the o2 differences are relevant. Just different Mfg.

Looking forward to seeing the results of the Leak Downs.