Engine reassembly

Hi all,

Do you guys put your engine bottom in the frame before the barrels and the head?
Or do you assemble it then wrestle it into the frame?

Could be a dumb question......but all this is first time!

'74 MKIIA

I put it all together on the bench then slipped it in the frame, bottom end, jugs and head as a unit.

The hassle of put the head on after the fact is greater than putting it in all together.
Later on when you have a free weekend to lap the valves or some kind of head maintenance, you can experience it the other way.

You'll gain no edge by having that critical area exposed if installing with the jugs and head off.

When installing the pistons and you drop a clip down there(you know where), you have a much better chance of getting it out. You can still turn the bottom end upside down and shake it out. Do it over an old sheet or the like to help validate success (not that you'll have to).

I feel there more you can do on the bench the more success you will have at start up. Better attention to detail is attainable under the light and at a comfortable work height.

I generally assemble mine with the bottom end in the frame first - that is after putting the gearbox in place. The frame itself acts as a nice stable platform for putting the rest together and I find a complete engine quite heavy and awkward to maneuver. I cover the crankcase when assembling pistons, but pvisseriii is correct that the head is more difficult to put on with the engine in the frame. I slacken the valve adjusters all the way out and hold the push rods in the head with a couple of rags until I get everything lined up, then pull the rags out. You can do it a number of ways, it's best to find what works best for you.

Since I was assembling my motor by myself, I opted to do it piecemeal. Gearbox and cradle, bottom end, barrel, head. I don't know if the early 750's are easier to put the head on, but I didn't have any problem. Put rubber bands on the rockers to lift them all the way up. Stuff the push rods all the way up past the rockers, hold with more rubber bands, install head, let rods fall into tappets, install head very carefully making sure the rods go into the rocker sockets and tappets. Tighten head in stages as you inspect the rod/rocker situation as you turn over the crank. Takes a bit of time, but if you don't want to lug the complete motor into the frame it works and you are not beating up the paint on the frame.

Pretty much like the early Workshop manual.

Dave
69S

I thought it was easier to put the bottom end in and then the top after because I was doing the job alone. Less weight, less struggle and all.

Hi

I do all my engine rebuilds on the bench, as soon as the bottom end is together I put it on a engine stand on the bench, its a good working height, but my 850 is in a Featherbed frame so putting the engine mounts on and the gear box/primary all together on the bench and just lifting it into place in the frame is a simple job for me, thats the good thing about Featherbed frames plenty of room to pull the motor/gear box/primary out in one hit as well as putting it back in.

Ashley

I've done it several different ways, settling mostly on doing the pistons & cylinders on the bench, then installing the lump in the frame, then the head.

Thanks much gents.........

lots to go by and much more confident now!!

How can you be sure that the pushrods sit on the pappets correctly??

According to Mick on his DVD, the rods should just fall into place, although I have heard of some that didn't. You can reach in while the head is blocked up and roll the rods around and feel them go into place. It's always best to be careful while tightening the head bolts to make sure nothing is binding. I keep rotating the crank carefully to notice nothing is interfering.

Dave
69S

I've never had a pushrod fail to seat properly in over 20 head installs so far...

I use vstrips of cloth to hold them in place in the head while I fiddle it in place.

pretty much can't tell if push rods seated on lifters, only the rockers, so only way to tell is slowly nip up head while rotating crank and not getting the SNAP-CLINK breakage or jamming sound till head snugged up. Nortons are a real mans sport to recover from now and then.

Never had issues with pushrod tappet seating. Always with rockers. Just a matter of procedure. A little assemble lube on the ball and socket helps to hold them in place as you cautiously bring the head home circling and checking to verify their placement.