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water pump pulley diameter

stevemiller333

stevemiller333

Contributing Member
I currently have a sherwood G5 with a 6.5" pulley on my 340.

I just came across a great deal and bought it.

Its a new sherwood G50 pump that I bought for 100 shipped on ebay.

The G50 has a 7.5" pulley.

Should I be worried about swapping out the pulleys? I now the g50 was used on 340's as well. What would be the difference if I did not swap the pulleys.
 
Pete is correct! The G50 pump with the 7.5" pulley will rotate less than the G5 pump with the 6.5" diameter pulley.
How much ????? You'd need to the do the math!

Circumference of the larger pulley would be 23.56"
Circumference of the smaller pulley would be 20.42"
In one crankshaft revolution, the larger pulley is lacking approx 3" of rotation at the circumference.
Or......... in approx 7 + crankshaft revolutions, the pump will have rotated one less revolution.

Ads suggest:
Raw Water Pump replaces Chrysler # 3619212, just like SHEG7B except with a 7 1/2" diameter pulley. Inlet: 1-1/4", Outlet: 1-1/4". Chrysler Marine Model LM318X and LM340X (3619212) Engine Model: LM318X and LM340X Engine Part Number: 3619212 Pump Availability: Obsolete Sherwood Replacement Pump: N/A Impeller Kit: 10615K Minor Repair Kit: 23976 Major Repair Kit: 23977 Inlet Port: 1-1/4" Outlet Port: 1-1/4"

 
you may hit a snag with the pulley swap,they are very flimsy and need to have the exact remover setup...if it gets bent she'll wobble and wear out the bearing
 
I'd leave it the heck alone and just keep an eye on the temp gage until you know the answer.

It's been my experience that the raw water pumps pump far more water than needed.

jeff
 
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