Will a post war crankshaft work in a 1943 engine block

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
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cab lizard
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Will a post war crankshaft work in a 1943 engine block

Post by cab lizard » Thu May 10, 2018 6:18 am

I would like to know if I can use a post war crankshaft in a 1943 engine block with timing chain set up are the end of the crankshaft the same


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Re: Will a post war crankshaft work in a 1943 engine block

Post by Joe Gopan » Thu May 10, 2018 6:31 am

The late crankshafts have no provision for oiling the lower sprocket. Some believe that the return oil from the oil Filter thru the timing cover is sufficient. I have no data on how that works.
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Re: Will a post war crankshaft work in a 1943 engine block

Post by cab lizard » Thu May 10, 2018 8:24 am

Thank you for your information on that for me Ben

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Re: Will a post war crankshaft work in a 1943 engine block

Post by OldPappy » Thu May 10, 2018 8:59 am

The return oil from the filter squirts a constant stream of oil into the timing cover while the chain and sprockets are in motion. I am thinking this should spray / splash plenty of oil onto everything inside the cover.

There are plenty of folks on here who know a lot more than I do about these Jeeps, so there can easily be something I am unaware of.

I am pretty sure I used a late crank in an early engine on a build I did back in the 80s. I recall having three engines as cores, and only one was a CJ engine.
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Re: Will a post war crankshaft work in a 1943 engine block

Post by cab lizard » Thu May 10, 2018 10:08 am

Thankyou old pappy for the that information that will help me out a lot on my rebuild of my engine

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Re: Will a post war crankshaft work in a 1943 engine block

Post by Lew Ladwig » Sat May 12, 2018 10:28 am

Yes! An early civilian crank works great. Just check to be sure the crank has an oil port to feet oil to the timing gear. Late civilian cranks that hole was phased out. The engine will run smoother and have more low end torque. Watch where the counter weight swings mid engine so it clears the oil galley plug. You can use a flush plug. There are some detailed threads on g503.com explaining this.
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Re: Will a post war crankshaft work in a 1943 engine block

Post by Rod Rushton » Sat May 19, 2018 7:57 am

Sorry to disagree with one who has considerable knowledge and experience - far more extensive than I will ever have, but here is my take on the subject:-
I am just rebuilding my motor, which is stamped GPW 77006 and dated on the crankcase skirt 10-2-42
To my surprise when I opened it up it was fitted with a post war CJ crank but still retained the chain drive cam. On the nose of this there is a groove which coincides with a pair of holes in the crankshaft timing chain gear/sprocket. According to my GPW TM and post-war CJ Manual the side view of the motor clearly shows drilling for the oilway from No1 crank pin via the No1 main journal. I checked this and sure enough there is a feed The manual also warned about the balance weights striking the oilway plug.
The cork seal in the nose of the crank between the gear or should I say chain-wheel and the oil slinger prevents leakage - so the chain is pressure fed. However, with the later CJ fitted with gearwheel cam drive take oil from the gallery though a jet which squirts oil between the gears - I believe this jet was later restricted in size possibly to assist in retaining pressure to the bearings.
Some time ago I read in "The All American Wonder" the author advocated sealing off the oil filter to increase pressure on the front main bearing - which I did. However, a friend of mine told me he had done this on his MB motor and the timing chain wore out in short order. I still don't understand why, but am happy now my chain is pressure fed - but I will still retain the oil filter and restrict the feed to this as a belt and braces move.
The crank chain-wheel I have just replaced was "F" stamped and dated 10-44. It is drilled between the teeth to allow the egress of oil to the chain, so it would appear the WW2 ones were pressure fed also
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