V-8 Conversion for the POWER WAGON by Chris Godfrey


So, you have been thinking about a V-8 conversion for your under POWERed WAGON.  Well here are a few of the pros and cons of the process.

 

1. STOP, how much time, money and expertise at fabrication do you have?

2. DON'T bother with it then, spend your money on the flathead. It is probably cheaper and you will retain more of you hair and sanity. Of course you may already be insane or you would have forsaken old iron in the beginning.

3. OKAY, you are reading this article right now, so that answers the sanity question. We will now proceed to detail the problems and materials associated with the installation of the small block Chevrolet into a pre '61 Power Wagon.

 

The small Chevy block is of a perfect size for the PW, the length and width of the engine preclude the necessity of butchering the firewall or frame. The following narrative deals with the installation of a 350 into a 1954 C1PW but should be generally applicable to the use of other small V-8's into the old beast of burden.

 

Materials used:

 

A. Chevy 350

B. Short water pump (to '70) a long pump from a mid '70's rig wont give radiator clearance on a pre '61 PW

C. Alternator bracket from late 60's Chevy P/U (left side mounting)

D. Hump back exhaust manifolds that go over the top of the spark plugs (50's to early 70's) These are necessary for steering box clearance.

E. 4 feet of 1/2 X 2" flat steel for motor mounts to use existing frame pads

F. GM SM 420 transmission ('48-'66?) (An NV 4500 would be nice if you $$$$$!)

G. U-joint and Female Yoke having 1 3/8" x 16 spline (one ton Chevy or GMC) This matches the splines on the PW intermediate shaft.

H. Clutch and brake pedals from early '60's Ford P/U w/hydraulic clutch

I. Master cylinder for clutch and brake from same or you could use others if you want to hassle with push rod lengths. I used both cylinders from a '68 Dodge P/U along with the proportioning valve. Adjustable push rods are necessary, as the Ford pieces are too short for proper functioning with these cylinders.

J. If you didn't want a PTO, then it is probably possible to use the original pedals and fabricate a clutch linkage. I used an old Arrow Gear PTO for the Chevy transmission.

K. 3/8" steel plate and 3/4" steel rod to make a bracket for the transfer case levers

L. The parking brake lever won't fit in the original location with the existing linkage rod. A cable linkage might be fabricated that would work.

M. Radiator hoses

N. 15" flex fan or an electric fan or both preferably

O. GM alternator with "one wire" self energizing conversion

P. HEI distributor (GM's greatest invention) or point type (HEI has about 3/4" clearance when motor is properly mounted)

Q. Electrical tape and assorted wires and connectors to extend the existing wiring harness unless you are doing a complete rewire.

R. The battery box must be relocated to the firewall on the right side.

S. The horn can be mounted using an existing inner fender bolt on the right side

T. Transfer case mounts or other suitable rubber for motor mounts

U. Suitable slave cylinder for clutch (I used the one from the 68 Dodge P/U and fabricated brackets to mount it to the Chevy engine on the left side). A 1960-2 Chevy P/U has a hydraulic clutch with the slave cylinder and release fork on the right side if you can find one. It also has a dual bore combination clutch/brake master cylinder but I am not sure if the Ford pedals will work with it. I opted for a dual brake master cylinder so I did not further explore this option.

V. Accelerator pedal from '64 to '71 Dodge P/U. this fits through the hole where the old starter pedal was using one of the existing holes.

W. Appropriate linkage rod for the carburetor used. I shortened the one from the '68 Slant Six to use on the 350.

X. 3/16 and 1/4" steel lines as necessary to plumb in your selected master cylinders.

Y. Chevy starter appropriate to your bell housing. I used the old 3 bolt cast iron type.

Z. New exhaust system, preferably duals to alleviate the need for a crossover pipe which would have limited clearance between the axle and oil pan. I had 2 1/4 pipe run from the manifolds back to 30" glasspacks mounted inside the frame and 2" tailpipes exiting just ahead of the rear fenders. This maintains an unobtrusive appearance if you don't see both sides of the truck to notice both pipes. The long glasspacks are fairly quiet together with the cast iron manifolds. It might be possible to find headers that would work but I prefer the cast iron manifolds for durability.

 

There you have it, a fairly complete list of what is required to accomplish the conversion. I am reasonably sure that I probably forgot something but I am not sure what it is right now.

 

Several other details need to be mentioned at this point, principally, proper location of the engine. The small block Chevy has spark plugs that stick straight out the side. This poses a clearance problem at the #7 plug (left rear) and steering gear box. I raised the engine up as high as I could without modifying the cab floor and canted the engine to the right just enough to get clearance for the plug. Even so, you can't get a spark plug socket on it, but you can use a boxed end wrench from the bottom.

 

The location front to rear is governed by the transmission tower and distributor. Basically, the engine is in the right place when the transmission tower touches or almost touches the cab floor where the hump bolts down. The hump has to be cut out forward of the existing tower hole and the new gearstick has to be bent rearward.

 

The rear mounts are 1/2 x 2" flat steel bent to go from the bell housing mounting pads over to the existing frame mounts on the PW. I used transfer case mounting biscuits as isolators at both front and rear mounts. The front mounts could be made from 3" heavy flanged angle iron with the flanges notched in the necessary places. I used 3/8 steel bolted to the front pads on the Chevy block with pads extending forward over the holes where the flathead was formerly mounted.

 

I will leave the small details of this fabrication to the individual as someone else can probably figure a better way to do it than I did.

 

How does it run?

 

With an estimated 300 gross horsepower, it is a definite improvement over the anemic 230. Third gear starts are the norm and shifts to high at 7-10 MPH on level ground are no problem. Fuel consumption with the 5.83's is horrendous at any appreciable speed above 35 MPH. The SM 420 transmission has a 7.05 granny gear which is lower than the NP crash box making low range virtually unnecessary for any purpose unless you are overwhelmed by a desire to break an axle. I have new 4.89's, which I will get around to installing someday. Meanwhile, I have to take the dog for a ride to make up for the month Ol' Red was down for the conversion. (See previously submitted photos of dog with three Power Wagons).


March 12, 2010