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Autopsy findings
http://slantsix.org/forum/viewtopic.php?f=30&t=64498
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Author:  MadScientistMatt [ Wed Feb 12, 2020 10:46 am ]
Post subject:  Autopsy findings

The 225 has developed rod knock on a dyno pull after making around 120 hp to the wheels on 5 psi of boost. So I've pulled the motor, and following Doctor Dodge's book, I've started a teardown. First find... this may be a sign I should be looking for another block to build instead of keeping the bragging rights that it's the original engine.

Attachments:
File comment: Looks like a crack under the casting numbers.
ominous.jpg
ominous.jpg [ 51.86 KiB | Viewed 1343 times ]

Author:  Reed [ Wed Feb 12, 2020 12:14 pm ]
Post subject:  Re: Autopsy findings

Was this after a rebuild or did you turbo the original unrebuilt 1966 motor? 120 hp and 5 ounds of boost seems like a low threshold for a rod knock to develop on a rebuilt motor.

Author:  MadScientistMatt [ Wed Feb 12, 2020 12:28 pm ]
Post subject:  Re: Autopsy findings

Turboed an unrebuilt motor with what I believe are 200,000 miles on it. The odometer's almost to 100,000 miles, and I have had several reasons to suspect it's been around at least once.

It also had a badly tuned blow through carb setup on it, with more boost, prior to the current turbo and EFI.

Author:  Reed [ Wed Feb 12, 2020 1:20 pm ]
Post subject:  Re: Autopsy findings

Ah. Lipstick on a pig, then. It was probably near death from age and the boost just blew it over the edge.

"1966 slant six, engine. A slant barely alive. Ladies and gentlemen, we can rebuild it. We have the technology. We have the capability to build the world's best turbo slant. This slant will be that slant. Better than it was before. Better, stronger, faster." 8)

Author:  hyper_pak [ Wed Feb 12, 2020 6:51 pm ]
Post subject:  Re: Autopsy findings

Crack, bad.
But I doubt that is the real problem if it's knocking.

Author:  MadScientistMatt [ Thu Feb 13, 2020 5:17 am ]
Post subject:  Re: Autopsy findings

hyper_pak wrote:
Crack, bad.
But I doubt that is the real problem if it's knocking.


Yes, I'll have more pics the further apart I get the motor. Just trying to document everything I find that's gone wrong here. There are three such cracks that I've found on the driver side of the block, which tells me I ought to be looking for a new core.

Author:  Charrlie_S [ Thu Feb 13, 2020 6:10 am ]
Post subject:  Re: Autopsy findings

MadScientistMatt wrote:
hyper_pak wrote:
Crack, bad.
But I doubt that is the real problem if it's knocking.


Yes, I'll have more pics the further apart I get the motor. Just trying to document everything I find that's gone wrong here. There are three such cracks that I've found on the driver side of the block, which tells me I ought to be looking for a new core.

Do you have a core? If not, I wouldn't be supprised if you could get one at the slant six racing Banquet, at the end of this month.

Author:  Dart270 [ Thu Feb 13, 2020 6:50 am ]
Post subject:  Re: Autopsy findings

Crack is probably not from the turbo if you only made 120 HP. That is one place they can crack, although I have never had it happen on one of my blocks.

Yes, one of us could bring a core block to the banquet in Pigeon Forge, TN on Feb 29 if you want to join us.

Lou

Author:  Charrlie_S [ Thu Feb 13, 2020 7:34 am ]
Post subject:  Re: Autopsy findings

Dart270 wrote:
Crack is probably not from the turbo if you only made 120 HP. That is one place they can crack, although I have never had it happen on one of my blocks.

Yes, one of us could bring a core block to the banquet in Pigeon Forge, TN on Feb 29 if you want to join us.

Lou


Looks to me, like it was caused by freezing.
Pigeon forge is only about 4 hrs from you.

Author:  Rob Simmons [ Thu Feb 13, 2020 8:15 am ]
Post subject:  Re: Autopsy findings

I gave Gary Bruner a buildable core he wound up not using.

I could bring another one up from KY, but need some advanced notice. I've still got stuff strewn about... :oops:

Author:  MadScientistMatt [ Thu Feb 13, 2020 10:15 am ]
Post subject:  Re: Autopsy findings

I'm definitely looking for a core. I appreciate the offers - I will need to check my schedule to see if I can make it to the event, and check my $1300 beater pickup to see if it can make it to Pigeon Forge. :)

The rod knock was very definitely the #6 rod bearing. My suspicion is that the pick-up was not letting enough oil through on the high RPM dyno pulls. The crankshaft looks like it could probably be turned undersized and saved. The rod, probably not.

Also, the cam lobes aren't looking in the best of shape.

Attachments:
cam lobes.jpg
cam lobes.jpg [ 39.7 KiB | Viewed 1236 times ]
clogged pickup.jpg
clogged pickup.jpg [ 56.94 KiB | Viewed 1236 times ]
rod journal.jpg
rod journal.jpg [ 43.32 KiB | Viewed 1236 times ]
rod out.jpg
rod out.jpg [ 43.77 KiB | Viewed 1236 times ]

Author:  Rob Simmons [ Thu Feb 13, 2020 11:31 am ]
Post subject:  Re: Autopsy findings

Yeah,... I’d say that con rod bearing is a bit hammered.... :shock:

Author:  DadTruck [ Thu Feb 13, 2020 11:55 am ]
Post subject:  Re: Autopsy findings

Quote:
the pick-up was not letting enough oil through on the high RPM dyno pulls


yes from the photo that pick up screen was blocked, for the next motor you may want to look at the
oil pump porting mods that Doc has posted here, nothing terribly crazy, but every little bit helps,,,,

the motor that I ran several slant drag race events in was the OE 68 Barracuda slant motor, the pistons, rings, bearings,
pushrods, rockers,,, were all OE parts.

took the motor completely apart, tagged and bagged everything, pistons , rings sets, bearings,,,so I could get them all back in the original location.
had the block and head and oil pick up/oil pan hot tanked, removed the end plugs and cleaned out the rocker shaft, cleaned up the rocker arms,,

used a ball brush to put a cross hatch back in the piston bores, power ported the pistons (that involves drilling small holes from the piston crown
to the top ring groove to put pressure behind the top ring groove). Bottle brushed all the passages. Re built the engine with all the: OE pistons, rings, bearings, rods,
rod bolts and head bolts, push rods, valves,,,. I put in a new timing chain, new 318 valve springs, a ported hydraulic motor oil pump, new gaskets, re ground cam and lifters, slight cut to raise
compression.
The piston bores and rods and crank journals are all out of spec for size and shape,,.

I have maybe 50 or so 6000 RPM runs down the strip.
Never an engine issue.

You can run an older motor hard, but if you want it to last, clean it out.

Author:  jcc [ Sat Feb 15, 2020 6:25 am ]
Post subject:  Re: Autopsy findings

Autopsy?

Looks more like 8x10 glossy crime scene photos.

Should be rated "R". :shock:

Author:  GregCon [ Sat Feb 15, 2020 3:05 pm ]
Post subject:  Re: Autopsy findings

I have a 225 I'll give you. Houston is very close to Georgia, so just drive over and I'll even load it for free and give you some cashews.

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