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1952-1968 M37 Small Block V8 Conversion

 

 

 

 

 

  This item is no longer being manufactured. I am trying to find as may pieces and upload drawings of the various components to help others in their conversion efforts.

 

(Tranny adaptor plate G-Code)

F15
G00 X 6.500 Y 3.150

G01 X 6.500 Y 0.750
G02 X 6.500 Y 0.750 J 2.40 I 0.000

G00 X 0.000 Y 0.000

G01 X 0.000 Y 4.000
G01 X 0.625 Y 4.000
G03 X 1.000 Y 4.375 J 0.375 I 0.000
G01 X 1.000 Y 7.000
G02 X 1.500 Y 7.500 J 0.000 I 0.500
G01 X 3.800 Y 7.500
G02 X 4.300 Y 7.000 J -0.500 I 0.000
G01 X 4.300 Y 6.500
G03 X 4.675 Y 6.125 I 0.375 J 0.000
G01 X 8.425 Y 6.125
G03 X 8.800 Y 6.500 J 0.375 I 0.000
G01 X 8.800 Y 7.000
G02 X 9.300 Y 7.500 I 0.500 J 0.000
G01 X 11.500 Y 7.500
G02 X 12.000 Y 7.000 J -0.500 I 0.000
G01 X 12.000 Y 4.500
G03 X 12.500 Y 4.000 J 0.000 I 0.500
G01 X 13.000 Y 4.000
G01 X 13.000 Y 0.000
G01 X 0.000 Y 0.000

M02

 

       

The following jpegs are outlines of the various pieces of metal that I used to make the M37 V8 conversion set. Above each piece is the CNC plasma torch program that is used to cut the piece out of sheet metal. If you will go to www.flashcutcnc.com you will find a program on their website that you can download for free that will display and run these programs. If you know someone who has one of these torches you can have them cut the pieces out of steel plate for you.

 

M37clutch1 (1/4" steel plate)

F25
G92 X 0.000 Y 0.000
G00 X 0.000 Y -0.250
G01 X 0.000 Y 4.800
G01 X 0.900 Y 4.800
G01 X 1.350 Y 3.700
G01 X 1.500 Y 3.000
G01 X 1.600 Y 0.000
G01 X 0.000 Y 0.000
M02

    

 

 

M37clutch2 (1/4" steel plate)

F22
G92 X 0.000 Y 0.000
G00 X 1.750 Y 2.250
G01 X 1.750 Y 1.500
G02 X 1.750 Y 1.500 J 0.750 I 0.000
G00 X 0.000 Y 0.000

G01 X 0.000 Y 4.000
G02 X 1.000 Y 5.000 J 0.000 I 1.000
G01 X 3.500 Y 5.000
G02 X 4.000 Y 4.500 J -0.500 I 0.000
G01 X 4.000 Y 0.500
G02 X 3.500 Y 0.000 J 0.000 I -0.500
G01 X 1.000 Y 0.000
G02 X 0.000 Y 1.000 J 1.000 I 0.000
M02

 

 

M37frntmnt1 (1/4" steel plate)

F60
M00
G90
G92 X 0.000 Y 0.000
G00 X 0.0000 Y 0.0013
G01 X 2.7000 Y 0.0013
G01 X 2.7000 Y 3.5013
G01 X 0.9500 Y 7.4013
G03 X 0.0000 Y 7.8513 I-0.9169 J-0.7079
G01 X 0.0081 Y 0.0000
G00 X 0.0000 Y 0.0000
M02

 

 

 

M37frntmnt2 (3/8" plate steel)

F22
G92 X 0.000 Y 0.000

M03
G01 X 0.000 Y 7.000
G01 X 2.700 Y 7.000
G01 X 2.700 Y 0.000
G01 X 1.600 Y 0.000
G01 X 0.000 Y 1.700
M05
M02

 

 

M37frntmnt3 (3/8" plate steel)

F22
G92 X 0.000 Y 0.000

M03
G01 X 0.000 Y 4.400
G01 X 2.700 Y 4.400
G01 X 2.700 Y 0.000
G01 X 1.600 Y 0.000
G01 X 0.000 Y 1.700
M02

 

M37frntmnt4 (3/8" steel plate)

F22
G92 X 0.000 Y 0.000
G00 X 0.000 Y -0.250
M03
G01 X 0.000 Y 8.900
G02 X 2.750 Y 9.160 I 1.390 J 0.000
G01 X 4.700 Y 3.200
G01 X 4.700 Y 0.000
G01 X 0.000 Y 0.000
M05
M02

 

 

M37frntmnt5 (3/8" steel plate)

F22
G92 X 0.000 Y 0.000
G00 X 0.000 Y -0.250

G01 X 0.000 Y 7.900
G02 X 2.100 Y 7.580 I 1.200 J 0.800
G01 X 2.100 Y 0.000
G01 X 0.000 Y 0.000

M02

 

 

M37lftrearmnt (3/8" steel plate)

F22
G90

G92 X 0.000 Y 0.000

M03
G01 X 0.000 Y 5.750
G02 X 0.500 Y 6.250 J 0.000 I 0.500
G01 X 2.300 Y 6.250
G02 X 2.800 Y 5.750 J -0.500 I 0.000
G01 X 2.500 Y 2.250
G01 X 2.500 Y 0.500
G02 X 2.000 Y 0.000 J 0.000 I -0.500
G01 X 0.500 Y 0.000
G02 X 0.000 Y 0.500 J 0.500 I 0.000
M05
M02

 

 

Kit for installation of V8 with later original M37 gearbox contains the following:

2 ea. Front engine mounts.

2 ea. Rear engine mounts.

1 ea. Throttle assembly.

4 ea. Rubber vibration isolators.

1 ea. Upper radiator hose and clamps.

1 ea. Lower radiator hose and clamps.

1 ea. Transmission adapter plate

1 ea. Pilot bushing.

1 ea. Clutch disc.

2 ea. Clutch fork pivot bearing assemblies.

1 ea. Throwout bearing guide tube extension.

1 ea. Hardware set for installation of these parts.

 

On your end you will need to buy the following:

1- Hayden 17" 6 blade flex fan, part number 3567

1- 318 or 360 engine with mechanical clutch type bellhousing.

1- 318 or 360 V8 flywheel and pressure plate, (the flywheels are not interchangeable).

1- 1961-1968 318 clutch pressure plate (if you are using the original gearbox).   


Kit for installation of V8 with later NP435 gearbox contains the following:

 2 ea. Front engine mounts.

2 ea. Rear engine mounts.

1 ea. Throttle assembly.

4 ea. Rubber vibration isolators.

1 ea. Upper radiator hose and clamps.

1 ea. Lower radiator hose and clamps.

2 ea. Clutch fork pivot bearing assemblies.

1 ea. Hardware set for installation of these parts.       

 

On your end you will need to buy the following:

1- Hayden 17" 6 blade flex fan, part number 3567

1- 318 or 360 engine with mechanical clutch type bellhousing.

1- 318 or 360 V8 flywheel and pressure plate, (the flywheels are not interchangeable).

1- 1961-1968 318 clutch pressure plate and disc if your tranny input is a 1" 10 spline or

    1969-1979 318 clutch pressure plate and disc if your tranny input is a 1" 23 spline.       

      These parts will allow you to bolt your new engine into an M37 using the original engine mount points. Your best bet for an economical installation is to find a good low mileage truck that has been totaled and buy the engine, flywheel and bellhousing along with any accessories including the power steering pump, hoses and brackets. If the donor truck is a 1972-1978 Dodge 4X4 with a reverse rotation saganaw steering gearbox, (when you turn the input CW the output should turn CCW) get that too and you will be ready to install your power steering as well. Or you can use one of our kits to install a Ford F150-250 PS steering box which costs less. Try to find a engine that has 4 bolt front mount flanges as they are stronger than the 3 bolt ones used on some of the engines.

      If you have a winch on your truck your best bet for a transmission is the original M37 one using our adapter kit. If you don't have or want a winch then just about anything will work that was intended for the 318/360 engines. NP420's and NP435's from 1961-1970's can be used. If you are using a 435 make sure that it is an early short output model and not one that has the rear engine mount attached to it. If you use the NP435 (my personal favorite) we have an adapter plate that bolts to the side of it and allows you to attach your original transfer case and Ebrake levers with it.

Preparation

 

      Read the chapter in your trucks technical manual on power plant removal, the following is only a basic outline of the procedure.

1. Remove your hood, fenders, fender liners and radiator with it's shell.

2. Next disconnect all the plumbing and electrical to the engine (don't forget the ground strap at the right rear of the engine).

3. Disconnect the intermediate shaft from the output flange of the transmission.

4. Attach a hoist to the lifting eye on top of the engine and lift the engine and gearbox out as a single unit.

5. If you are going to use the original transmission with our adapter kit you will need to remove and save the following parts: Transmission, throwout bearing assembly and its return spring and anchor bolt and the clutch fork assembly and linkage.

6. Thoroughly clean and inspect everything. This is a good time to replace all of your brake and fuel lines if you haven't done so already.

7. Find the exhaust manifold template and lay it on the left upper frame with the inside edge even with the inside edge of the frame top. Place the forward end against the rivet head as shown below and mark the area to be cut out. This is to allow room for the left exhaust outlet.

8. Next you will have to remove some metal from the left rear engine frame mount. You can use the template provided as a guide.

 

Installation of M37 transmission

1. There are two dowel pins located at the lower rear of the engine to bellhousing mating surface. If you will tap these in about half way you will be able to install the flywheel, clutch disc and pressure plate before installing the bellhousing. After everything is together use a drift and hammer to tap them back to their original locations.

2. Install the flywheel.

3. Some of the original clutch forks may be bent out of alignment. If you are having problems installing it in your bellhousing so that it turns freely you should check its runout. To check and straighten yours you will need to chuck the long shaft end into a lathe and make sure that the other end doesnÕt wobble when the lathe chuck is turned. If it does tap the outer end with a hammer until it runs true within 1/16".

 

4. Cut 3/8" off the end of the short bearing end (as shown below) so that it will clear the inside of the V8 bell housing.

 

5. Install the 9/16" OD X 3/8" ID "keysert" into the lower right hole inside the bellhousing as shown below. This is done by applying permanent loc-tite to the threads and screwing it into the hole until it is flush with or slightly below the top of the hole.

 

6. Install the right pivot fitting using the 9/16"NC X 1" and 3/8"NC X 1" bolt and split-loc washers provided.

 

7. Next insert the clutch fork into the inner bearing and install the outer bearing on the other end as shown below.

8. Move the outer bearing plate around until the clutch fork ends are centered in the 5-1/8" transmission hole and the vertical measurements from the surface the bellhousing is sitting on to each fork end are the same. Also check to make sure that the center lines of the 3/4" I.D. bearings to the bottom flange of the bellhousing are the same and that the fork shaft moves freely.

     Now check to make sure that the outer bearing plate is flush against the side of the bellhousing. You may have to loosen the inner bearing bolts and move it around a little to achieve this. When everything is perfect, transfer the location of the 4 plate holes to the bellhousing andÊdrill them out with a number 7 drill and tap them 1/4"NC.

     If after you tighten all of the bolts the clutch fork does not rotate freely use the shims provided to change the angle of the outer bearing plate so that the inner end of the clutch shaft is lined up with the inner bearing.

9. Use long fiber wheel bearing grease to lube the fork pivot bearings then secure the plate to the bellhousing using the four 1/4"NC X 1" bolts and washers provided. The installation should look like the photo above. A 1/8" hole has been provided in each bearing for future lubrication (yearly should do) although you will have to remove the bottom flywheel cover to access them. Use a #2 needle point lube fitting.

10. Install the transmission adapter plate to the bellhousing using the four 7/16"NC X 1-1/2" flat head machine screws. Make sure that the mating surfaces are clean and lightly primered to prevent rust. Use loc-tite on the bolt threads.

 

11. Below is a picture of the position of the clutch components without the bellhousing and flywheel so that you can see their relationship to each other.

 

12. First install the pilot bushing in the crankshaft recess as shown below using a 3 LB. Hammer and a block of aluminum to protect the bronze bushing. The chamfered end goes toward the flywheel. Make sure that the recess is clean so that the bushing can seat itself properly.

13. Next install the throwout bearing guide tube extension as shown below. This extends the guide tube to the length of the one used with the 318 bellhousing. If you don't have access to a press you can carefully tap it into place using a hammer and an aluminum drift. Slide the throwout bearing up and down the tube to make sure it doesn't hang up at the seam line. If it does use a fine file to dress the transition between the two tubes (this should be less than .005").

 

            

 

14. Now install the clutch disc with the long hub side aft towards the transmission. An extension has been welded into the clutch disc hub so that it can engage the shorter splines on the M37 input shaft.      Use a clutch disc centering tool or an old input shaft to center the clutch disc before tightening the pressure plate. Place the pressure plate over it and fasten it down with its bolts tightening them in a star pattern, 3 turns each at a time.

 

15. Now drill a 5/16" hole in the top of the bellhousing as shown below and tap it 3/8"NC. Then install the throwout bearing return spring and bolt.

16. Next slip the bellhousing over the flywheel assembly and bolt it to the engine block. Don't forget the 2 7/16"NC bolts on the bottom inside of the block flange. Then insert the throwout bearing assembly from the bottom of the bellhousing and hook the spring to the hole in the top finger of the throwout bearing.

17. Now slide the transmission input shaft into the rear opening of the bellhousing, through the throwout bearing and clutch disc and into the pilot bearing. This procedure is aided by putting the transmission in gear and turning the tail shaft until the input shaft splines line up with the disc splines. You will probably have to remove the outer clutch fork bearing plate so that you can reach your hand in to guide the throwout bearing into place.

18. Attach the transmission to the adapter plate with the four 9/16"NC X 1-1/4" bolts and split-loc washers. You may have to grind a small amount off the end of the bolts to keep them from bottoming out against the adapter plate.

19. Check the underside of the transmission to make sure that the shaft cover of your transmission isn't bottoming out on the bellhousing. You should be able to insert a .002" feeler gauge between them, if not remove the gearbox and grind a few thousands off the face of the cap to gain clearance.

20. Fasten the right rear mount to the ear provided on the right side of the transmission adapter plate and left rear mount to the bellhousing using four 9/16"NC X 1-1/2" bolts and split-loc washers. Install the clutch bellcrank on the clutch shaft with it's woodruff key and bolt. Your engine should look like the photo below.

 

21. You will have to cut the PTO shift lever half way through 1/2" up from the pivot point and bend it outward until the edges of the cut touch each other. Weld the cut, then make another cut on the inside of the lever 1/2" below the lower shift handle bolt hole. Bend the lever inward until the edges of the cut touch and weld. This moves the lever 1/2" to the left so that it comes out in the correct place in the tunnel cover. Note: if you try to bend the lever without cutting it first you will break its pivot bracket. Another way would be to remove the lever and place it in a vise, heat it and bend it. See photo below

 

 

Installation into the truck

1. Attach the front mounts as shown below using four 7/16"NF X 1-1/2" or 1-3/4" long bolts split-locs and nuts. Tighten the nuts just enough that you can still move the mounts up and down.

        Below is a photo of the left front mount partially installed on a 360 engine. Notice that the mount ears go behind the block ears on this side. Also notice the .340" spacer plate that is installed on the inside of aft ear, this is used on the 360 engine installation only. If your engine has 3 bolt mounts like the one pictured here, install the fourth bolt through the mount ear and spacer plate. If you are installing a 318 V8 you will not need the spacers. If you have the choice get an engine that has four hole mounts instead of three hole as they are stronger.

            

 

        Below is a photo of the right side mount. Notice that the ears go to the front of the block ears and once again if you are installing a 360 there is a .280" spacer that goes between the rear mount ear and the rear block ear.

            

 

2. Align the front mounts so that they are level with the engine and on the same plain with each other. This is easily done by placing a straight edge across the tops of the mounts and moving both of them until they both lie flat against the straight edge, and the straight edge is parallel with the fuel pump as shown below.

 

3. Find the right and left rear bolt and rubber mount assemblies and run the special round nuts about half way on and off to make sure the treads do not catch. It's easier to do this with them off the truck than installed in the mounts. Below is a photo of the 4 mounts. The two on the left are the front mount rubbers and bolts. The upper right one is for the right rear. The lower right one is for the left rear. The special step nuts on the rear mounts fit into the 1-1/8" rear mount holes.

4. Make a chain sling and attach it to the four corners of the engine block (there are four 3/8"NC holes in front of and behind each head). The lift point should be about 3" behind the carburetor with the gearbox attached. Lift the engine unit enough to clear the front of the frame, the rear should be a couple of inches lower than the front. Move the engine into place lowering it as necessary until the engine mounts line up with the frame mounts. Place the 1" thick rubber disc under the right mount and the 5/8" thick one under the left one and set the engine down until the rear engine mounts just rest on them.

                

5. Remove the lower 9/16" bolt that attaches the left engine mount to the bellhousing and insert the 5/8"NF X 3" bolt that holds it to the frame. Install the nut and run it up finger tight. Next reinstall the lower 9/16" bolt you removed and tighten both it and the upper one securely. Then tighten the 5/8" bolt making sure the boss on top of it's nut fits up into the 1-1/8" hole in the frame mount. This will lock the rear left corner of the engine into place.

6. Now do the same with the right rear mount. This will be easier if you firstÊloosen the two 9/16" bolts that fasten the engine mount to the transmission adapter Once the 5/8" bolt and it's rubber discs areÊproperly tightened you can retighten the 9/16" bolts. The engine should now be locked into it's final position.

 

 

7. Next install the 1-7/16" rubber discs between the frame and engine mounts and lower the engine. Install the 1/2" bolts from the bottom, place the 1/2" thick rubber pads and 1/2" plate washers on top of the mounts and install the lock nuts. You should now level the frame of the truck by laying a spirit level across the frame sides just in front of the engine. Once the frame is level you can lay the level across the rocker covers to make sure the engine is level to the frame sideways. In the fore and aft direction the front of the engine should be slightly higher than the rear. You can adjust the mounts to bring the engine level if it is off. Obviously the frame must be level before leveling the engine. When you are finished the mounting surface for the carburetor should be level both fore and aft and sideways.

            

 

8. Your clutch linkage will need to be lengthened about 1/2" The easiest way to do this is to cut it in half and run a 3/8"NC die down each half. You can then run jam nuts on and connect the two halves with the threaded barrel nut provided in the kit. This will allow you to fine tune your clutch adjustment.

9. Now install the linkage using the original clevis pins and adjust the clutch pedal for 1/2"-3/4" free play. Make sure that the stop block is still in place bolted to the floor panel to act as a stop. This determines the rearward position of the pedal and keeps the linkage from going over center. You may have to increase the thickness of the stop to get both the position of the pedal and the free play correct.

10. Reinstall your emergency brake and transfer case shift levers. Before hooking up your link rods, adjust the clevis ends 1/2" tighter (to compensate for the transmission being 1/2" further aft than the original location).

11. Hook your intermediate shaft back up to the transmission.

12. Install the throttle linkage by bolting it to the back of the engine using the 3/8"NC X 3/4" bolt and split-loc washer provided. Attach the threaded link between the carburetor and the throttle linkage using the clevis pins provided. You will have to grind the original gas pedal rod's lower end to 1/4" thick so that it will fit into the clevis on the lower end of the throttle linkage.

 

 

13.    Your tunnel cover should fit without modifications. You may have to bend your ebrake and transfer levers a small amount to the left to clear the right edge of their opening.

 

Exhaust system

       For the exhaust system your least expensive and easiest way to go is to install dual mufflers (I got mine new for $21 each same size and shape as the original). Put one under each running board and run flex pipe from them to cutoff 318 exhaust pipe stubs attached. To the manifolds. A dual system keeps you from having to deal with a crossover that interferes with both the PTO and the front drive shaft.

 

Using a front crossover

      Pictured below are the two kinds of exhaust crossovers. The left one is a forward cross over that goes around the front of the oil pan. This is the one to use as it requires less modification than the rear cross over pictured on the right.

               

             Below is a photo showing the area where the PTO shaft hits the exhaust crossover.

                  

 

Ê      Below is a photo of the front of the crossover where it goes around the oil pan. A 2Ó section needs to be cut out of the pipe as indicated by the duct tape that is wrapped around it. The two ends of the pipe can then be brought together and spot welded while the crossover is installed on the truck. After this is done the pipe can be removed and welded all the way around then reinstalled.

       Also notice how close the exhaust comes to the fuel line. It would probably be best to move the fuel line upward so that it is above the exhaust pipe. Although the possibility of starting a fire is remote, getting the fuel too hot inside the line can cause vapor locking during hot weather.

               

 

Below are some photos of the rest of the exhaust system. Off the shelf 90 degree elbows and flex pipe where used so that no special fabrication was required.

               

               

 

 

Hooking up the winch

      There is not enough room between the 318 bellhousing and the original PTO shaft to use the original u-joint. You will have to use the chain coupler supplied with the kit. It is installed the same way as the original u-joint using the original shaft keys.

       Below is a photo of the coupler installed on the PTO output with the pto shaft ready to be slid into the other end of the coupler. Make sure that both sprockets do not engage the same shaft otherwise the coupling will not be able to articulate to compensate for shaft misalignment. It is not necessary to align the keyways in the coupler since it doesnÕt need to be in phase with the u-joint at the other end of the shaft. Also notice that the shaft has been flipped around so that the splined end is at the winch.

       Since the sprockets are a tight fit onto the shafts the easiest way to install the coupler is to remove its chain and install each sprocket on its shaft separately. After sliding the PTO shaft into place and holding the sprockets against each other, you can wrap the chain around them and reinsert the master link. You will need to remove a small amount of the bellhousing flange at the rear edge to clear the OD of the coupler.

                 

Starters

      There are two ways to go as far as starters are concerned. You can either use the original 318/360 gear reduction starter. Which costs about $50 core charge included. If you do you will have to cut out 1/2" of lip on the lower frame web to clear it. The other option is the 1990's Nippon Dinnso starter used on the cummins diesel powered dodge trucks. It is small enough to fit in the space with no modification to the frame. The down side is that it costs $150 with core charge. This is one pissed-off little starter! It weighs less than half of what the original does and cranks the engine 30% faster! Even though it costs 3 times as much I will never use anything else. The problem is that if you want to carry a spare for trips into the back woods you end up with $300 invested in high tech starters. You might want to start scrounging to see if you can find a used one cheap. The Chrysler part# is 53005984 The ND part# is 128000-7810   12V 12N15

 

 

 

 

 

 

 

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