Crankshaft L-4 Interchange

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Brad Gates
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Crankshaft L-4 Interchange

Post by Brad Gates » Wed Jun 14, 2017 11:15 am

Guys,

Rebuilding a 1952 L-4 engine and I have a Crankshaft that is cracked beyond use. It came from a gear drive cam/crank. I have a donor crank but it had a chain drive cam sprocket. It appears that there is a "groove" in the gear drive crank, possibly for oil lubrication. Will the crankshafts interchange? In other words can I use the donor chain drive crank in this application? Thanks for your help.

BRAD


Joe Gopan
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Re: Crankshaft L-4 Interchange

Post by Joe Gopan » Wed Jun 14, 2017 1:38 pm

Install it, the crankshaft gear will block the oil flow from the passage in the front of the crank shaft.. I have built several gear type engines and installed NOS GPW Crankshafts.
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Brad Gates
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Posts: 704
Joined: Sun Dec 22, 2002 6:47 pm
Location: Pennsylvania

Re: Crankshaft L-4 Interchange

Post by Brad Gates » Thu Jun 15, 2017 4:59 am

Thanks Very Much,

Studied the cranks this morning and understand what you describe. I thought the oil passage was to get additional oil on the chain, but also reasoned that the gears would need more oil than a chain. Anyway, the machine shop is moving forward again.

Thank you for the help.

BRAD

Joe Gopan
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Re: Crankshaft L-4 Interchange

Post by Joe Gopan » Thu Jun 15, 2017 5:07 am

That oil hole is for the chain sprocket. If want a little peace of mind, you can smear some Permatex #3 inside the Crankshaft Timing Gear. The fit of the gear is sufficient to restrict any loss of oil pressure. My own M-38A1 has a GPW Crank in it that was installed new 47 years and tens of thousands of miles ago.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO


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