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Problem found
https://slantsix.org/forum/viewtopic.php?t=60275		 Page 1 of 2
Author:  Mechanized [ Thu Oct 06, 2016 8:41 pm ]
Post subject:  Problem found
So I recieved that NOS distributor which makes the truck alot more streetable. To keep the ping away I ended up running right at 8 degrees. The reason I avoided the 8 degrees was that the engine idled so rough in gear. After new head work I should have checked for blow by. Well warm it has a very steady stream of blowby. So now I find myself trying to determine the best course of action. The sad thing is other than a few dings the truck is fairly rust free.

Any one know of a good source of quality rebuild parts?

I have been reading that you can remove .1 from the head surface. On a 86 head is that feasible? Bigger valves? What do I need to know?

Goal would be a few more ft lbs of torque.

Cheap air oil seperator for the time being?
Author:  Joshie225 [ Fri Oct 07, 2016 9:40 am ]
Post subject: 
You need to investigate and correct the source of the poor cylinder sealing before trying to get more power. If you don't you're likely to destroy more parts as oil is almost certainly going into the combustion chamber lowering the effective knock rating of the fuel. You can easily end up with detonation which breaks rings and pistons. I've torn down two 225s with every top ring broken from persistent knocking.
Author:  SlantSixDan [ Fri Oct 07, 2016 11:23 am ]
Post subject: 
Josh is right.

Also, yeah, you can find a variety of figures thrown around Mill 0.100" off the head, mill 0.090" off the head, mill 0.060" off the head, etc. Fact is, there's no "cookbook" figure like this that applies safely and effectively to just any/every Slant-6 engine. If you intend to shave the head and/or block, you really need to measure the combustion chamber volume and the piston deck height so you know what you're starting with.
Author:  Mechanized [ Fri Oct 07, 2016 3:32 pm ]
Post subject: 
Thanks for the info. The spark advance computer is likely the cause which is gone now. I have no detonation or spark knock now. The cylinder walls looked good when I had the head off. It isn't my daily driver. I get about 2.5 hours a week to play with it. Week to week I forget where I was lol. I have not owned it that long.
Author:  Mechanized [ Fri Oct 07, 2016 3:33 pm ]
Post subject: 
I am talking more power on total rebuild. I am not ordering parts yet. Anyone have engine parts brands I should stay away from. Should I swap back to a head from an earlier year? Should I build on the current hydraulic head?
Author:  Jase [ Fri Oct 07, 2016 7:49 pm ]
Post subject: 
Quote:
Thanks for the info. The spark advance computer is likely the cause which is gone now. I have no detonation or spark knock now. The cylinder walls looked good when I had the head off. It isn't my daily driver. I get about 2.5 hours a week to play with it. Week to week I forget where I was lol. I have not owned it that long.
If you have not owned it long... there may be some deferred maintenance related work needed before deciding to invest the time, energy and several hundred's of dollars on a rebuild..

How much blow-by are you talking about? Has the truck been sitting a lot and potentially have stuck rings? Have you done a compression test? How about a leak down test? Yes all of which will cost you time and effort, and a little $$, but you will be in a better position to know what your options are. As for a rebuild where you are looking for a more torque, stock style parts should do fine.
Author:  Mechanized [ Sat Oct 08, 2016 11:04 am ]
Post subject: 
I could get manometer numbers. I plan on doing a compression test tomorrow along with a leak down tesr. I found the burnt valve via a leak down test. The bores were so clean I didn't think much about a new head causing blow by. I will report more tomorrow with pics and maybe a video.
Author:  Mechanized [ Sun Oct 09, 2016 4:39 pm ]
Post subject: 
Compression numbers are all right at 120 except number 2 which is at 138.
Author:  Mechanized [ Wed Oct 12, 2016 11:01 am ]
Post subject:  Update problem solved.
So I ran the leak down numbers and nothing, absolutely nothing stood out. I pulled the rocker cover and removed the rocker rail. I did leak down at various stages of piston depth in the cylinder and found my gauge to always be well within the green with 80lbs of supply air. This took a bit of setting it up to prevent the engine from rolling over. It proved to be very tedious. I was also fighting huge amounts of ping. Blow by was pretty nasty as well. I taped my vacuum gauge to the windshield and went for a drive. Bouncing needle all over the place. Fast forward next morning I start it and the truck goes to high idle. When I came back outside there was huge amounts of soot on my siding. Thought nothing of it because I was tired. I put some hours in after my second job on this. I kicked it down and put it into gear to move it. Well I back up foot on with the brake applied, load on the engine, timing at 3 dbtdc due to ping it is idling as smooth as glass. Pull the pcv off and the blow by was minimal. I point the mirror at the pipe and rev it. Chunks come flying.
Author:  Jase [ Wed Oct 12, 2016 4:30 pm ]
Post subject: 
Do I understand that you have rebuilt the head?

That the truck pings often?

That the vacuum gage bounces while driving?

That it had lots of blow by, but after a leak down test, it showed normal amounts of blow by? and chunks of something came out of the PVC hose when racing the engine? or was it oil?

What do the spark plugs look like?
Author:  Mechanized [ Wed Oct 12, 2016 4:37 pm ]
Post subject: 
When I got it, it had a dead miss. Pulled the 5th plug wire no change. Leaked down the 5th cylinder. Air through the exhaust verified by actuating the egr valve. Rebuilt head. Lots of blow by. Bouncing needle while driving. Chunks of melted cat out the tail pipe on warm up this morning including the sooty powder on my siding :( truck idled fairly normal and smooth. I removed the plug on the exhaust manifold and the rpm was so high that I couldn't adjust it down. i will sleep tonight but i should get around to removing the cat by saturday or sunday.
Author:  Mechanized [ Wed Oct 12, 2016 5:07 pm ]
Post subject: 
Head before rebuild

Image
Author:  Jase [ Thu Oct 13, 2016 3:16 pm ]
Post subject: 
Quote:
When I got it, it had a dead miss. Pulled the 5th plug wire no change. Leaked down the 5th cylinder. Air through the exhaust verified by actuating the egr valve. Rebuilt head. Lots of blow by. Bouncing needle while driving. Chunks of melted cat out the tail pipe on warm up this morning including the sooty powder on my siding :( truck idled fairly normal and smooth. I removed the plug on the exhaust manifold and the rpm was so high that I couldn't adjust it down. i will sleep tonight but i should get around to removing the cat by saturday or sunday.
What is the vacuum like at idle?

how about the plugs? Soot out the exhaust is usually rich air/fuel I believe..
Author:  Mechanized [ Thu Oct 13, 2016 6:53 pm ]
Post subject: 
I bought it and did the head right away. At that time I put the suggested NGK UR4's plugs in.

I did the HEI swap right along with the head or shortly after. I couldn't get it to stop pinging. I went so low as 3* btdc. The only change was extreme drivability change. I pulled the plugs at that time and noticed they were hot (white/ashy). I noted that ping came the most about 5 minutes after full warmup.

I changed the PLUGS to Ngk UR6's because they are two stages colder. I was thinking this would provide some decent ping avoidance. It did not.

So I filled with 93 octane after running it out of fuel essentially. This helped get me some pedal without ping. I had been playing with EGR and rigging up the charcoal can. I unhooked the charcoal can from only the pcv port on the carb for fear of it running the engine lean for some reason. I gave the EGR full ported vacuum for some ping protection. I gained no ground.

All the while in neutral the vacuum gauge is bobbling softly between 16 and 18. In gear under load the gauge was bouncing ten divisions. I pulled the pcv and opened the oil cap after driving and found the tons of blow by vapor rolling out.

Then the morning with soot on the siding from the tail pipe.

I cut the cat off tonight and the there is only one very small portion of cat that I can put a 1000 lumen flashlight to and see through. Yes I know it is a honey comb or at least should be. The front portion of the comb is melted. I have not had the time to put a pipe back in place. My neighbor has a new baby so I am waiting to start it until the pipe is in place.
Author:  Mechanized [ Sun Oct 16, 2016 8:59 am ]
Post subject: 
Cat removed and pipe in. No detonation sounds. No ping. I am currently at 6 degrees BTDC. I will be moving it up again once I get normal fuel back into it. I am at 93 octane no corn at this point. Vacuum is at 20 inches when warm with a slightly buzzing needle. Meaning it has a very vast vibration. The needle is not moving even 1/16th of an inch but it is not solid and firm. I may need to check it against a known good running vehicle and see what it reveals. I think I may have left it on the intake manifold too long.
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