Qunicy Loopers FC64 FG52 FC62

[Frank Volker]

Frank,

You could try taking a very coarse file and light running over the surface to remove the bumps. Next, you could put some coarse grit (220?) wet/dry sandpaper on a very flat plate and use a light rotary motion (holding head flat). Next, look at the head and check for flatness. Do the same on the bolt side. Do this for both heads. When things are flat, either scrape or hand sand a small radius on the edge that I've pointed out in the attached photo. The total arc of the radius is something around 90 degrees. It isn't critical, but try to make them all equal. The purpose of the radius is to provide a smooth transition of surfaces (maintain Coanda attachment) for the incoming scavenging fuel charge.

I'm not sure what causes the pitting. It could be some interaction with the painted gasket or simply deterioration of silicon or magnesium in the casting alloy. It goes without saying that if you can, you should test the heads and block for water leaks before assembling.

Frank

[fbref5269]

frank,

what you are saying then is machining may not be needed just clean up with the file and wet/dry? will always be at the bottom of the combustion chamber? i'll get the file and try it tomorrow.

learning something new every day. thanks frank.

frank

[RogerH]

Frank,
The heads on FD67 were in very good condition. I don't have any of the pitting you have. Would attach a picture but they are bolted to the block for media blasting and I don't have them back yet. The radius makes sense - great information. BTY, I ordered the GB-1112 bearings this evening.
Roger

[Gene East]

Frank N. and Roger

Listen to what Frank Volker tells you. He was a very inportant part of the Looper development program.
Frank holds an engineering degree from the University of Missouri. He wrote his thesis on 2 cycle engine exhaust systems. He used to talk to me about first harmonics and second harmonics and I had no idea what he was taking about. He designed pipes and I just welded what he designed .
Frank spent endless hours in the Dyno room at Quincy Welding.
I know for a fact that he wore out one dyno,perhaps two.
Few people have his credentials

Frank V.
Are you coming to DePue???

[Frank Volker]

frank,

what you are saying then is machining may not be needed just clean up with the file and wet/dry?

Yes. I'd try that before laying out cubic $ for machining.

will always be at the bottom of the combustion chamber? i'll get the file and try it tomorrow.

learning something new every day. thanks frank.

frank

The radius side is always the side toward the exhaust port. So, that would be the BOTTOM of #1 and #3, and the TOP of #2 and #4. It appears from your photos that #2 was sufficiently hammered to almost completely remove the radius. In the 3/4 photo, I can see a radius on #3, but almost no radius on #4, which shows little damage; maybe caused by insufficient head/piston clearance. The radius on #1 looks pretty much intact and could probably be used as a dimensional guideline for the other 3.

Almost always, the damage begins with a pin becoming loose and then exiting the ring land. Next, the ring spins in the groove until it hooks on the exhaust port. It almost appears in the photos that the pistons were making head contact. This could lead to the pin-escape and general breakage problem. I don't recall the exact dimension, but I think the deck clearance should be flush to about -.002 down when assembled. Also, there should be no protrusion of head gasket into the cylinder.

Frank V.

[fbref5269]

frank v,

looking close at the heads i see number 2 cyl took a nasty beating. that was the toughest piston to get out and had the dirt in it. i will be trying to smooth out the bumps this weekend. and i will tell you of my progress. your input is priceless. i was talking to roger the other day and saying how furtunate we are to have the crew from quincy following our progress.

more to follow. thanks frank for all your help.

frank

[F-12]

Thinking back I seem to remember a type of Epoxy that my Dad used one time in an emergency that withstood high temps and pressure. We had a ring problem with the Nitro A motor and broke it during trsting. Dad pulled it down at the trailer, smoothed it off as best he could and filled the deep spots with this 2 part goodie. We won 2 reats of A and I don't think Dad ever took the engine apart again. It ran until I changed over to DOH (2 or 3 seasons). Don't remember what it was but it might be worth looking into...........

[fbref5269]

charlie,

that might have been devon. as a matter of fact there is some used on the crankcase in cyl #1. that stuff will fix about anything.

frank

[F-12]

That is a good possibility. I know it was tough and I know Dad used it to build an A 'stock' horsefly merc to stuff crankcase and pad the cylinder head. That one was for when he knew someone was running a non stock motor. It was as fast as a B motor and as soon as we smoked the field, Dad would put it in the trailer and say "As long as there are guys breaking the rules, you'll see alot of that motor. If you play nice, we'll leave it in the trailer." Go Dad............

[Skoontz]

is what we used on Mc91B and 101B's in go carts. They used to design the engine to mount any way, upside down, left side, right side etc...And, what you would do is plug the ports using devon. So assume the cylinder was a square, and the side that had intake would be opened, then you would plug the side to the right...Then the side opposite intake would be exhaust, and you would plug the side to the right of the exhaust....Decide the cart handled better with the engine moved or twisted, just pull the epoxied plugs and shove em in the holes that you need to plug all over again.....