Slant Six Forum
https://www.slantsix.org/forum/

Buster - Long Rod, Light Pistons, Light Crank Alm. Block SL6
https://www.slantsix.org/forum/viewtopic.php?t=29183		 Page 11 of 13
Author:  Doc [ Mon Oct 12, 2009 11:51 am ]
Post subject: 
Yes, I have also purchased a set of the narrow K1 rods.
From talking with Tom at K1, I got the last set... he is starting another batch.
DD
Author:  Dart270 [ Mon Oct 12, 2009 2:08 pm ]
Post subject: 
Good to know they are selling these. I still need to get my narrow K1's to the shop to get a bearing clearance on my crank and then that short block is ready to go together.

Lou
Author:  Doc [ Mon Oct 12, 2009 3:39 pm ]
Post subject: 
Quote:
...Seeing that Buster has tight side play on the con rods, no oil spurt holes, tight crank end play and tighter cam to cam bearing (block) fit... this engine should not need a lot of extra low RPM oil volume...
The oil pan came-off last night and I feel that the thinking above is what killed this engine.

#1 rod bearing had obviously over-heated to the point where the slender, 12 point rod cap nuts failed, then all h#!! broke loose inside the engine.

So what does this have to do with con rod side clearance and spurt holes... reduced oil flow over the bearing surface at higher RPMs.

My notes show that the rod bearing oil clearances were all set at .0014 - .0016 I know this for sure because I actullay sent the crank back to the shop and opened these clearances up to that number.
Con rods # 1 & #6 were both tight on side clearance... both of those rods had .002 to .003 of side play.
Guess what, con rod bearing #6 was also overheated and ready to fail, #1 just happened first.
Side clearance on 2 thru 5 were in the .004 to 007 range.
I still need to open-up those rods and look at the bearings but if my thinking is correct, I will see more bearing "distress" on the bearings in the location(s) that have less side clearance.

So my current thinking is that the factory spurt hole and recomended .007 to .014 of con rod to crank journal side play, allows a pathway for an "engineered" amount of oil flow. Reduce the amount of oil volume at the bearing and the bearing overheats and fails.
DD
Author:  Joshie225 [ Mon Oct 12, 2009 4:38 pm ]
Post subject: 
Wow, what a bummer. This sounds like a lubricant cooling failure rather than oil starvation. Interesting mode of failure, but it still stinks.
Author:  Dolmetsch [ Tue Oct 13, 2009 2:37 pm ]
Post subject: 
I would aim to the high side for side clearance . Also i would like more bearing clearance too. At least .002"
Does the engine have full groove mains? (or a grooved crank. )

Don
Author:  Doc [ Fri Nov 06, 2009 10:17 am ]
Post subject: 
The lower main bearing inserts were "partially grooved", I would say there is 240 degrees of pressurized oil feed.

I worry more about the oil flow into the crank bearings on all Aluminum SL6 engines seeing that the oil flows into the main bolt bosses and has to flow up and around the main bolt shank, before entering the bearings.
(I have to think that the Chrysler engineers got the flow path's volume "right")

Anyway... I pulled the Buster engine and took the pan off... what a mess.
You know you have trouble when you see this:

Image

And this...

Image

Long story short, this block is now junk. :cry: :evil:

Image

If it was just a "big hole in the side" I could weld that closed but somehow... a big chunk was also knocked-out of the bottom of cylinder #2. :shock:

If you look closely at this photo, you will see a long crack, running up the front side of the engine... the whole left front corner of this block is ready to fall-off.
DD

Image
Author:  SlantSixDan [ Fri Nov 06, 2009 11:55 am ]
Post subject: 
*moment of silence* :cry:
Author:  Dart270 [ Fri Nov 06, 2009 12:37 pm ]
Post subject: 
Drat.

I hope to try this w/ the K1 rods at some point. I found a machine shop that doesn't blink when I ask about custom machining as would be needed here. My first cast crank motor is about to come out of that shop, so we'll see how that runs first.

Lou
Author:  Polara1974 [ Fri Nov 06, 2009 12:58 pm ]
Post subject: 
Too bad ... really a pitty ... one aluminum block long gone, and Doc didn't even had the chance to enjoy it a little ...

R.I.P. Buster ....
Author:  hantayo13 [ Fri Nov 06, 2009 1:18 pm ]
Post subject: 
if you not breaking parts ...you arent trying hard enough


keep on roddin'
Author:  Shaker223 [ Fri Nov 06, 2009 2:44 pm ]
Post subject: 
did it let go without warning?
Author:  Doc [ Fri Nov 06, 2009 2:52 pm ]
Post subject: 
This failure happened fast.
I saw the engine temp gauge move from a steady 185 up to 200 degrees so I slowed the car from 70 MPH to 55 and pulled to the right lane. Then I thought I heard something... and boom, the engine blows-up.
DD
Author:  robert west [ Sat Nov 07, 2009 5:19 am ]
Post subject: 
sorry to here what happened.you know what you were doing is traditional hotrodding at it's best.building hot rods is all about taking a idea run with it and seeing how it all turns out
Author:  Doctor Dodge [ Sat Nov 07, 2009 8:47 am ]
Post subject: 
Thanks for the support and feedback...

I need to "regroup" on the Light Rotating Assembly (LRA) concept and do another one... one that will stay together long enough to get some real performance data.

If I salvage the good parts from Buster, get a couple of replacement pistons and rework the crank, I can have another "go" at the LRA idea. Next time around, I think I will do the build in a cast iron block. :idea: :roll:
DD
Author:  terrylittlejohn [ Sat Nov 07, 2009 3:06 pm ]
Post subject: 
so doug what `s the weak point ? did the rod bolt or cap fail or was it the bearing form lack of oiling. :cry:
Page 11 of 13 All times are UTC-07:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/