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-   -   Special 2 piece 400 Crankshaft Found Today (https://forums.maxperformanceinc.com/forums/showthread.php?t=849685)

thepontiacman 04-09-2021 03:57 PM

Special 2 piece 400 Crankshaft Found Today
 
Check out what I found in this 400. Not a good thing to find. Late 70's 400.
2 pieces now.https://uploads.tapatalk-cdn.com/202...b7c8fa085d.jpghttps://uploads.tapatalk-cdn.com/202...11688b09cb.jpg

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einstein 04-09-2021 06:22 PM

If they fracture just right, they still run. The knock is rather odd.

4zpeed 04-09-2021 06:35 PM

Quote:

Originally Posted by einstein (Post 6240991)
If they fracture just right, they still run. The knock is rather odd.

I'll bet my water pump is going south... :oogle:



Frank

PontiacJim1959 04-09-2021 06:44 PM

An 800HP shot of nitrous from a stand still will do that.

694.1 04-09-2021 09:48 PM

well, photo 1 clearly shows a hole!

PAUL K 04-09-2021 10:15 PM

I had one of these cranks in a 76 455 TA engine... It still ran just knocked a lot!

https://www.facebook.com/PaulKnippen...9523455937204/

Very rare option

Half-Inch Stud 04-10-2021 08:10 AM

Quote:

Originally Posted by 694.1 (Post 6241024)
well, photo 1 clearly shows a hole!

. Drill hole.

Made me look at CYL 1; looks like a dented lower CYL.

4dblnkldude 04-10-2021 08:14 AM

Quote:

Originally Posted by PAUL K (Post 6241026)
I had one of these cranks in a 76 455 TA engine... It still ran just knocked a lot!

https://www.facebook.com/PaulKnippen...9523455937204/

Very rare option

I've chased that knock before. I sold my neighbor a 455 for his 70 lemans, just a crank and block. He had the engine built locally by a well known guy. Thing was a runner dynoed at 520hp. Stock e heads, roller cam, etc. After 100 miles it started knocking. We had that effing trans out twice, flexplate magnafluxed, a new converter, the driveshaft balanced you name it. The car sat for two years and he finally got back on it. We pulled the engine and took it back. Yep the crank was cracked, had good oil pressure though.

Chief of the 60's 04-10-2021 08:37 AM

Quote:

Originally Posted by einstein (Post 6240991)
If they fracture just right, they still run. The knock is rather odd.

Exactly

I once bought a real nice '66 GP with an engine knock. Drove it about 20 miles home with the A/C blowing ice cubes. Took it apart, and the crank was in 2 pieces.

mrennie 04-10-2021 08:40 AM

Quote:

Originally Posted by thepontiacman (Post 6240955)

Great picture to show the "overlap" of rod and main journals. There isn't as much as you would think when viewed from this angle.

Very glad my factory 455 crank has larger mains to maintain as much overlap as possible!

flamedabone 04-10-2021 08:43 AM

This happened the last 25 miles of a 3000 mile trip. The oil pressure hovered around 20 and she knocked like hell, but she made it all the way home.

https://hosting.photobucket.com/albu...080&fit=bounds

-Abone.

thepontiacman 04-10-2021 08:47 AM

#1 main brg. Spun .When I pulled timing set off , the one side of the main brg slid out. Took rod nuts loose and there was lots of movement of the broke part of crank.
Main cap is chipped around dial pin.
Cylinders look good, so far.
Align hone/bore and replace crank/main cap and it may be good to use.
Going to put another short block in it's place to sell.



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gtohunter 04-10-2021 11:17 AM

2.8 GM V6...Drove it home. Clutch was a little squirrely though!:)


https://i.imgur.com/YgSZqVd.jpg?1

goats2quick 04-10-2021 01:03 PM

had one break just like the one in the first pic.
most people said that a bad ballancer caused it.


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