Posted by Brian in Oregon on Wednesday, October 25, 2000 at 02:59:59:
In Reply to: BRIAN :Please reply; I'm doing a 318 conversion, posted by Mike Murray on Wednesday, October 25, 2000 at 00:20:17:
My 318 is partly dismantled for inspection.
From the water pump fan pully face (the x or + shaped piece) to the rear face of the block (what the bellhousing mates to) appears to be 30 1/2".
The width w/o exhaust manifolds is 20 1/2". Each centerdump manifold appears to add 2 1/2", so make it 5" for the pair, totalling 25 1/2" wide.
The only drawback to the NP420 is lack of synchro in 1st and 2nd. If you can live with that, then I don't see a problem with it. If you are clumsy with double clutching, then it will be that much harder to pull a trailer.
How much heavier a trailer? Keep in mind that the M37 is not exactly the world's best tow rig due to all power going through the tranfer case to get to the rear axle.
I would not use an aluminum bellhousing with an unsupported transmission. Ray and I are of the opinion that a severe landing will allow the mass of the trans to keep going, snapping the bellhousing. Stick with cast iron. Better safe than sorry.
What I say generally applies to the PW as well as the M37, though I'm fuzzy whether the early NP420's used in early PW's were even synchro'd in 3rd and 4th.
If you are going to tow a car trailer a lot or drive long distances with it, perhaps dropping in a 318/360 with an automatic with a married transfer case, and putting in a centered rear axle with 4.89 gears would work better. If I heard correctly, the hubs will interchange with the 1960's axles so you can keep the 5 bolt pattern. Then you can change the front axle to 4.89 as well.
Ray had a PW (I think a WDX) with a such a centered rear axle at his shop when I visited.
One more thing... Ray's kit moves the NP420 back only a 1/2 inch from stock. That is easily compensated for by the adjustments in the transfer case levers, the driveline slip joint and won't affect the trans floor cover plate much.