Posted by Charlie on Monday, November 20, 2000 at 23:03:13:
In Reply to: engine swap for M37 posted by Mike Rohr on Monday, November 20, 2000 at 12:17:36:
Comments like "Dodger"'s are best left unanswered, there's a term in accounting: "GIGO"
First of all, if Ray Suiter makes a part or a kit, it's high quality and a good value. Remember that length is in short supply, and you might want to install a Ranger overdrive (ratio = 0.73:1 in OD) in front of the transmission. A SM420 is only 10.5" long (Ranger = 7") and 3rd = 1.70. A SM465 ('68 and later) is 12.0" and 3rd = 1.57. So the split in OD os better with the 420 (1.24) than the 465 (1.146). But if you're sure you don't want an OD, then the 465 is stronger, easier to find and 3rd is closer to 4th than a 420. The gigantic jump from 2nd to 3rd (111% in the 420, 127% in the 465) isn't a problem with a 350 V8, it would be a big problem for a 4 cyl diesel. I have an 86% jump from 2-3 and 3-4 in my Hercules/Clark M37, and acceleration is slow; but 4-5 is only 25% and once it gets up to ~45 mph acceleration is great. These are the pros and cons of a SM420 vs. SM465.
You could of course consider a 6.5 diesel, the late versions are 290 ft-lb nat. aspirated and 385-430 ft-lb turbo. The stock NV4500 would be best for this; 5.83s might be kept with a NV4500 and 38-40" tires (maybe with a 350 also, the 4500 works for it also and 5th = 0.73 or 0.74, depending on before or after late '94). A properly geared 6.5 in a M37 would be quick and get 18-20 mpg on the highway and 13-14 mpg "around town".
Advance Adapters make many conversion kits for GM small blocks and it'd be worthwhile to look at their catalog which is readable online. Possibly some parts from some or another kit would be useful.
The NP420 would theoretically be adaptable to a GM bellhousing. The input shaft should be shortened 0.50-1.00" (it's 7.5" vs. GM's 6.5"). The pilot diameter for GM = 0.590", the Dodge is 0.750". A disk with the 1.00" 10 spline hub would be needed. Pre 68 GMs have a input shaft bearing retainer OD of 4.686", 5.125" after that. Dodge is usually 4.75". This is critical for properly locating the gearbox. The hole could be milled out 0.064" if it's an early bh. If it's late, then a ring exactly 0.1875" thick and about 0.375-0.50" wide would be needed. Measure everything, don't take my word. It might be nice to make the ring 0.001" too small and then have to warm it up to about 250 F. to slip it on; then it'll really stay put.
After the gearbox is properly "located" a machinist can drill 4 new mounting holes.
Cabell Garbee has, I believe, an Advance Adapters Ranger overdrive set up for GM in front and NP420 in the back. I think he'll sell it for a reasonable price if he still has it. The Ranger even with 5.83s and stock 9.00-16 NDs will drop 60 mph rpms to 2520. 38.5-38.7" 11.00R16 Michelins or Boggers (38.5X11.00-16) will drop it down to 2300 at 60.
Food for thought.
Charlie