How to assemble a 701 motor

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I couldn’t find a full thread on a motor build up so… as I recently built a motor for someone, I decided to create a build thread to assist anyone else who decides to build/rebuild their own motor.

The motor that I built here was a 701-62T cases with a 61X cylinder. It had the intake manifold and carbs already on it. Also, the exhaust manifold was already bolted to the cylinder. Not a big deal, but if it weren’t on there then it would have been a bit easier.

First of all, you want to make sure that all of the parts are accounted for! Nothing worse than getting into it and finding out that you are missing bolts. I lay everything out by the section I am working on.

Below is a list of the bolt sizes and the torques specs for each bolt. Notice that there are two specs for each. Torque each bolt to the first spec the first time through, and then come back and torque to the next spec as a final pass.

BOLT: SOCKET SIZE: 1st torque Final torque (ft-lb)
Case Bolts 12mm 11 20
Bed Plate 14mm 17 34
Cylinder 14mm 17 29
Head 12mm 11 26
Flywheel 17mm -- 51

Once you have all of the parts and they are clean and ready to go:

1. Begin by flipping the TOP half of the cases over so the pins are showing. (The bearings of the crankshaft will fit into them when it is installed in the cases) It is best to use blocks of wood or something similar to elevate the case half to allow for the rod to hang through.
***The crank seals must be installed a certain way. (see pics)

(I test fit everything before I final assemble it)

2. Install seals onto the crankshaft and lay it in the cases. Be Sure to apply a thin layer of grease to the seals where they slide onto the crank. Make sure that ALL of the bearings line up with the pins in the cases. Use your hand to try to turn each bearing to make sure it is secure. Now that the crank is half way in, I like to put oil in each bearing before sealing up the cases. Just pour some R50 down between each bearing.

3. Apply a thin layer of 1211 to the surface of the case halves to seal them when tightened down. Line up the BOTTOM half of the case BEFORE pushing it down flush. Double check to see that the oil seals are lined up with the right groove in the case half. Once they are lined up, press the cases together. There are 8 bolts that hold the cases together and another 7 that hold the mounting plates on. (The tightening order is listed on the bottom half of the case)

Once everything is tight, you can flip the bottom end over and begin assembly on the top portion of the motor. This is also a good time to apply some oil to the bottom rod bearings while they are accessible

 

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pics...

 

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This motor had a fresh bore and all new pistons and rings. Before installing anything, I push each ring down into the cylinder apx. 1-2 inches (using the piston) to check the ring gap. Use a set of feeler gauges to measure the clearance of the gap. Normal clearance should be around .022 (ish)

***You can also check clearance by inserting a feeler gauge on the side of the piston and pushing it into the cylinder. This is an quick way to do it, but I suggest doing it the other way instead.

4. For each piston, insert ONE ring clip into one side. This will allow you to push the piston pin in without having it push out the opposite side.
***The ARROW on the top of the piston ALWAYS points to the exhaust. Make sure you pay attention to this when installing the pistons onto the rods.

5. Dip each rod end bearing in oil before sliding into the end of the rod. Make sure it is well lubricated. I used R50 for this build. Slide the bearing into the top of the rod and place the piston over the end of the rod. Line up the pin and then push it all the way in until it stops at the clip on the other side. Now install the extra clip. (repeat for other side)
***Cover the crankshaft with a towel or something just incase the clip from the piston falls as you are trying to put it on. You don’t want to have to chase it down inside the cases…. NOT fun!

 

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6. Install stator onto the end of the crank. Be sure to line up the timing marks. There are two Philips head screws that hold the stator to the cases. Slide the rubber piece with the wires into the top of the case. There are grooves that it fits in. Once this is done, you can install the bendix gear.

7. The bendix I was working with had some surface rust on it so I had to sand it off. Make sure you use waterproof grease on BOTH ends of the bendix. I gave it a little extra to keep it lubricated. There is a small washer that goes on the backside where the bendix slides into the cases. Once the bendix is in, you can move on to the flywheel.

8. Rotate the crank so that the key hole is on top. Insert the flywheel key and then line up the groove for the flywheel and press it on. You will feel it automatically pull itself on due to the magnets on the stator. The flywheel bolt should have a small bit of oil on it before you thread it in. DO NOT USE THREAD LOCK. This about the ONLY bolt on the motor that you don’t use thread lock on.
Use a crow bar to hold the coupler while you tighten the flywheel bolt. This will keep the motor from rotating as you tighten it down.

 

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9. The front flywheel cover for this motor is from COLD FUSION. It’s a great billet replacement part that uses an o-ring instead of a gasket to seal it. Because it is an o-ring, I didn’t have to use any 1211 here. If you are using a stock cover with a gasket, apply a thin layer of 1211 to each side. There are 7 – 10mm bolts that hold the cover on. I don’t torque them, I just hand tighten them.

10. On to the top end. Insert rings into grooves of each piston. The small writing on the ring faces UP. They will only sit one way so you will know if you put them on wrong. There are small pins that the meet up with when compressed. (see pics)

12. Install the base gasket DRY! No need for 1211 or any kind of sealer on this gasket.
It helps to have a friend assist with installing the cylinder. It is possible to do it yourself, but if you have the help- use it. ☺ Use your fingers to compress both rings on the piston equally. Check to make sure they line up with the small pin and then begin to slide the cylinder down over the piston. The skirts of the cylinder make it a fairly easy process. (repeat this step for the other piston)

13. Once both pistons are in the cylinder and you have checked to make sure the rings have not been pinched, the cylinder will slide easily down onto the cases. Make sure both dowels in the cases align with the cylinder, and then install the 6 bolts.

 

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14. Now that the cylinder is on, rotate the crank to make sure it spins smoothly and the pistons are installed correctly.
***I like to apply a very thin coat of R50 to the cylinder walls. Some people run it dry, others put a lot of oil, so I split the difference.

15. Finally, when installing the cylinder head, make sure the domes are clean and not knicked. The OEM head gasket has a sticky coating on both sides of it, but I still applied a thin layer of 1211 to each side just because that’s how I do it. It makes for a better seal. Test fit the gasket to make sure the holes for cooling line up with those in the cylinder. Some head gaskets will have “UP” stamped on them to make it easier. This particular one did not.

Torque all the head bolts down in the numbered order that appears on the top of the stock head. If it is an aftermarket head, same rule applies – start in the center and work in a circular direction – out ward.

Not as in depth as a manual would be, but I think the pictures are well worth it. Good luck on your build. Hope this helps out a bit.

 

[Matt_E]

Moved to Tech FAQ and stickied. :biggthumpup:

Very nice job.