Matt's Combat Commando overhaul by GrandPaul

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Crank & cam in place, case halves nipped up-

Matt's Combat Commando overhaul by GrandPaul


Megacycle even includes special cam lube-

Matt's Combat Commando overhaul by GrandPaul


Breather in place-

Matt's Combat Commando overhaul by GrandPaul
 
Oil pump lapped in, cleaned up & installed with new gasket-

Matt's Combat Commando overhaul by GrandPaul


Cam drive bits installed and loctited in place. Hint: always install the oil pump drive worm gear LAST of all!

Matt's Combat Commando overhaul by GrandPaul


That's it, bottom end is done.
 
grandpaul said:
Rods installed, very nice smooth rotational action-

Matt's Combat Commando overhaul by GrandPaul


JB Weld in the forward sump pickup location-

Matt's Combat Commando overhaul by GrandPaul


New crank seal and some more JB Weld in the previous mechanic's holes drilled to tap out the original bearing race. All you need is an oven at 250 for 15 minutes and they drop right out, so why drill the cases?

Matt's Combat Commando overhaul by GrandPaul
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Just an observation GP
Why are there extra holes drilled at the top of oil pickup hole on the timing side crankcase? :shock: I can see you putting JB weld at the forward hole but you have basically made a straw with a hole in it, which will only suck oil into the oil pump when the level reaches the top most hole. You did the cut away mod on the other crankcase side for the bottom hole to get access to the original oil pickup. We had a good tech talk with dynodave at the rally and his mod addresses the problems with the INOA tech digest mod by drilling a hole on the drive side crankcase at the oil pickup hole location (same size as on the timing side) and then using very small drill with a number of bored holes calculated for the same area to allow oil to seep in but leave any big bits from getting picked up and jamming the oil pump. Especially he made a primitive but effective screen for the Combat series crankcases. Also I like the reed valve mod on the timing side and you blanked off the original oil breather location but wouldn’t you drill some extra 3/8th holes through the timing side to allow the downward piston pulse to flow more to the timing chest. Just curious
CNN
 
CanukNortonNut said:
Why are there extra holes drilled at the top of oil pickup hole on the timing side crankcase? :shock: I can see you putting JB weld at the forward hole but you have basically made a straw with a hole in it, which will only suck oil into the oil pump when the level reaches the top most hole. You did the cut away mod on the other crankcase side for the bottom hole to get access to the original oil pickup. We had a good tech talk with dynodave at the rally and his mod addresses the problems with the INOA tech digest mod by drilling a hole on the drive side crankcase at the oil pickup hole location (same size as on the timing side) and then using very small drill with a number of bored holes calculated for the same area to allow oil to seep in but leave any big bits from getting picked up and jamming the oil pump.
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Half a dozen of one, six of another. Or, more than one way to skin a cat?

The sump only needs to fill to about 1/4" deep for the pump to start drawing off, even less under accelleration with pooling effect. The total area of the holes drilled is slightly greater than the main pump inlet channel diameter.

The old breather riser tube (up the backside between the case halves to the timing side hole at the rear under the old magneto location) will serve more than adequately to draw off initial crankcase pressure, then the crankcase becomes a low pressure environment. It's an overall simple solution as-is.
 
Ya really got to spin up a Combat in anger to appreciate the air friction loses to pump pulses through tiny factory vent holes compared to opening them up &/or adding more which also lowers the peaks of pressure pulses as more volume to dilute them. Its fairly subtle until you keep a Combat on cam before and after freer breathing. This has about nothing to do with mere pumping down to below atomsphere except less density some what less friction but the velocity of passage through too tiny holes. I had open 3/4 hose w/o any baffle on magneto take off that stay while glove dry no matter how long I over rev'd past Peel. I have sense the lower ventilation speed did not carry oil mist into TS to matter a whitworth. Peel's pCV was rather close to oil take and still worked a treat, if just oil weep the main issue to bother breather system. The remarks PCV works better near the crank case than farther way leaves me wondering how that is known or if just wishfull thinking.

If reeds must be close to crank to work best then that implies more pressure pulse spikes as lost engine work even if keeps the oil weeps away.

Matt's Combat Commando overhaul by GrandPaul
 
Quote "The sump only needs to fill to about 1/4" deep for the pump to start drawing off, even less under accelleration with pooling effect. The total area of the holes drilled is slightly greater than the main pump inlet channel diameter."


Ok GP
Looking back at my pictures that I took of this mod. which I can now see that its not such an issue.

Never mind. Carry on. I'm enjoying this thread.
Regards,
CNN
 
Cam followers in place in the cylinder block, loctite & safety wire on the retainer screws-

Matt's Combat Commando overhaul by GrandPaul


Pistons in the bores, note the green & red painted ends of the compression ring expander visible on the right side piston, those are a bit of a fiddle to get set in place correctly! Miraculously, all 4 compression rings checked out EXACTLY at .010 end gap. New base gasket, of course-

Matt's Combat Commando overhaul by GrandPaul


That's it, mid-section done. Note how Combat high compression pistons come up proud of skimmed cylinder deck-

Matt's Combat Commando overhaul by GrandPaul
 
Cylinder flange nuts all loctited in place and properly nipped up-

Matt's Combat Commando overhaul by GrandPaul


I was about to pull my t-shirt off and cut a couple of strips to shove into the pushrod tunnels in the head, then I noticed I had the plastic bags from Megacycle that had the cam followers in them; folded in half and rolled up, they worked a treat to retain the pushrods in the head while I lowered it in place onto the cylinders-

Matt's Combat Commando overhaul by GrandPaul


That's the ticket! loctited all the head bolts and nuts in place and nipped them right up-

Matt's Combat Commando overhaul by GrandPaul


Top end done. Tranny next...
 
Sorry folks, completely forgot to get shots of the valves & springs building up, and the rocker & shaft assembly as well.

It seems every build has a different overall selection of pix, and this one missed the bare head to complete head process.
 
Paul

why on gods green earth would you put lock tight on head bolts and barrel nuts!!!!! first off you should use a lubricant so as to give a more consistent torque and as you HAVE TO RE TORQUE these fasteners several times you have negated the lock tight when you do this along with made it IMPOSSIBLE to achieve an accurate torque figure. this shows me along with the oil pick up mod you have NO idea what what you are doing!!!!!
 
Since Comstock showed that the 72 breather location is more than adequate you could have used that location instead of the timing case.
 
And I'm going to keep right on doing it that way!

Funny, the drillings were Windy's idea in the first place...
 
grandpaul said:
And I'm going to keep right on doing it that way!

Funny, the drillings were Windy's idea in the first place...
Click to expand...

just keep up with the WRONG use of lock tight and you will have warranty issues and showing just how NOT to do things. as for the sump mod that is a FAR CRY from the way I do it. I DO NOT remove the weir I DO NOT carve out the drive side case sump and I DO NOT use large holes. I do plug the front pick up hole and drill a series of .109 holes in both sides so as to act as a strainer.

Matt's Combat Commando overhaul by GrandPaul


Matt's Combat Commando overhaul by GrandPaul
 
Windy, didn't you formerly do the drillings in the lower timing side gallery and block off the upper/front opening?
 
what you see in those pictures is the way I have done it from day one!!! another thing I don't understand is this statement

"The old breather riser tube (up the backside between the case halves to the timing side hole at the rear under the old magneto location) will serve more than adequately to draw off initial crankcase pressure, then the crankcase becomes a low pressure environment. It's an overall simple solution as-is."

IF you are still using the original breather location along with the timing cover mod that is another problem you have created by removal of the weir. WHAT is the crank rotation?? which way is it forcing the oil to go?? you guessed it RIGHT UP THAT BREATHER with out the weir to help stop it.
 
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