using a v-belt 3.9 in a serp belt truck

Drillbit

Drillbit

Well-known member
Oct 12, 2005
5,943
1
Glasgow Ky
I sold a customer a 3.9 out of a 90 RRC with V belts. He is trying to install it in a 95 Disco with serp belts. I told him he would need to use his old front cover and a spacer. He was cool with that. I had that backwards, you have to use a spacer to put a serp belt engine in a v-belt truck. When he tried to put the front cover on the crank is 1-2 inches short and doesn't have a key way. Is there a work around for this? Is he (and by extension me) just screwed?
 
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robertf

Well-known member
Jan 22, 2006
4,788
360
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I don't know if it will work. Obviously the keyway slot will need to be lengthened and the key replaced with the correct type.

Is he using the 3.9 balancer, or a 4.0/4.6? 3.9 is bolt together and has timing marks, 4.0 is one piece no timing marks. The bore depth is deeper on the 3.9 for a shorter crankshaft.
 
WILL.TILLERY

WILL.TILLERY

2
Apr 20, 2004
6,928
226
Floyd, Virginia
We have done several vbelt to serpentine belt conversions here. Somewhere during the Vbelt lifespan there was indeed a change in the keyway on the crankshaft. I am pretty sure it was 93.... on a 93/94 the swap is straight forward... Before that date not so straight forward.
 
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robertf

Well-known member
Jan 22, 2006
4,788
360
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from How to Power Tune Rover V8 Engines
On these engines the crankshaft nose (sometimes referred to as the 'snout') was the same length as on all previous engines, but the key/keyway was longer. An early 3.5, 3.9 or 4.2-litre engine's crankshaft key was long enough to drive the new crank driven oil pump, but was not sufficiently long to also engage an 'interim' engine's crankshaft damper keyway
Click to expand...
 
4Runner

4Runner

Well-known member
May 24, 2007
663
111
Boise Idaho
That was my experience during the conversion on a 4.2. I just needed to have the keyway lengthened and am using a longer key.
 
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