Head scratcher

[Road Trip]

I remember that. They made a big deal out of "bay to bay venting" I think they called it. Each of the "V Twin" bays--1 and 2, 3 and 4, 5 and 6, 7 and 8 which were separated from each other by the main cap webbing--could vent to it's neighbors more readily.

BINGO! Thanks to you sharing the specific terminology, at last I was able to find a photo showing (and thread discussing)
the long-term fix for this high rpm LS motor oil consumption issue:

You must be registered for see images attach

(credit: ls1tech bay window / crankcase breathing discussion)

As a bonus, I found the GM TSB from this era (#01-06-01-011D "Information on Engine Oil Consumption Guidelines")
and attached this .pdf file for your viewing pleasure.

Funny how engines can be even more complicated than they look at first glance. Again, thanks for sharing, for I was
starting to doubt whether I'd ever actually read about this long term fix for the fluttering ring issue that was done
by windowing the main bearing webbing of certain LS blocks.

 

[L31MaxExpress]

After 3 days of different trips and 350 miles, misfire on #3 is back. I am determined to fix the issue and I have some 7.350" pushrods on the way. I ran into a rocker to retainer clearence issue with the shorter 7.200" pushrod attempting to pre-load the LS7 lifters as much as I wanted to attempt to run them at. I am going to the longer pushrods and will be first adjusting the lifters to be preloaded within about 0.040-0.060" off the bottom of their travel. I have atleast 1 lifter ticking on most cold starts and the engine misfires at idle when it ticks, then 30-90 seconds later it goes away. I think that is contributing to fuel fouling the #3 plug. #4 was oil fouled and #3 had some fuel fouling signs before. I have found that the LS7 lifters have 0.220" of internal travel and the stock LS7s have them pre-loaded 0.120 to 0.130". I am going to run them atleast to the stock LS7 preload and attempt even more. I am not afraid of floating the valves and causing pump up in this setup with the substantial spring pressure but I have a feeling that spring pressure is collapsing the lightly pre-loaded lifters when it is shut off and sits. The lifter then has to pump back up once the engine is running which takes a bit of time with cold, thick oil.

 

[L31MaxExpress]

Finally bit the bullet and ordered a smoke machine. I am going to smoke test the intake while the valve covers are off and see what it reveals.

 

[Scooterwrench]

Finally bit the bullet and ordered a smoke machine. I am going to smoke test the intake while the valve covers are off and see what it reveals.

Think you have a hole in it? I've been giving up cigs, well, trying and got one of those electronic cig things. I call it my hooka. I got to thinking it wouldn't be too hard to turn one of these things into a smoke tester.

 

[L31MaxExpress]

Think you have a hole in it? I've been giving up cigs, well, trying and got one of those electronic cig things. I call it my hooka. I got to thinking it wouldn't be too hard to turn one of these things into a smoke tester.

It would certainly explain some other symptoms I have recently noticed. My IAC has shifted to where it has 0 counts at hot idle in Park with the a/c off. Also getting some oil on some spark plug threads. When it stopped raining I pulled #3 plug, oil the threads, carbon on the ground electrode, slapped another plug into it and the misfire subsided. There are many places that could be a potential vacuum leak under the valve covers. Intake gaskets, rocker studs, and intake valve seals to name a few. I have seen engines that smoke like an oil fired battleship that did not have as much oil on the plug threads as my #3 plug did.

I did order some Autolite 3926s. It is completely possible that the AC Delco Rapidfire 5s are just too cold of a plug. I had much hotter 41-629s in it for a year and they burned clean but I suspect those were too hot due to some knock counts that dissappeared with a colder plug. The Rapidfires are an extremely cold plug. Finding a plug that is hot enough to burn off deposits and yet cold enough to work under heavy throttle has proven to be a challenge.

 

[Scooterwrench]

Hopefully just an intake gasket leak. How will you see the smoke if it's leaking into the lifter valley? Dist. hole?

 

[Scooterwrench]

What if you just pulled the upper intake and intake rockers and pressurized the crankcase through the dist. hole. Then you could listen down the intake runners for air leaks. I wouldn't put much more than 10psi on it for fear of blowing out the front and rear seals.

 

[L31MaxExpress]

Hopefully just an intake gasket leak. How will you see the smoke if it's leaking into the lifter valley? Dist. hole?

Valve covers are coming off anyway. If the intake is leaking into the lifter valley, smoke will be obvious. I am changing to longer pushrods. Valves will be closed when I smoke the intake. A smoke tester makes ~1 psi, atleast the one I ordered does. For under $75 it comes with smoke fluid, has an onboard compressor and a ceramic heating element. It is powered off the vehicle battery as well.

I actually hope it is a rocker stud leaking myself. The sealer I put on them did not seal on the first set of head bolts either.

 

[Pinger]

Think you have a hole in it? I've been giving up cigs, well, trying and got one of those electronic cig things. I call it my hooka. I got to thinking it wouldn't be too hard to turn one of these things into a smoke tester.

For some things - eg, establishing where the other end of a duct/conduit/drilling emerges, a mouthful of cig smoke or vape vapour blown directly from the mouth can be effective. Not so much for what L31MaxExpress is doing though.
I believe here in UK smoke testers are made from a soldering iron wrapped in a rag soaked in baby oil. No idea how pressurisation is achieved.

 

[Scooterwrench]

These hooka's use vegetable glycerine as the base for the juice and it makes huge clouds of smoke(vapor). I'm thinking maybe a fan out of a computer or a fart fan to push the smoke. Use a piece of PVC pipe with the fan in one end and hang the heater coil just ahead of it in through the side of the pipe. The coil has to be fed with a constant supply of glycerine to keep the smoke rolling.