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ADVANCING CAM SHAFT IN 220

advancing a cam by just advancing it is shade tree BS, who knows what the cam's intake centerline is GROUND at , to start off with! I have yet to meet an A/C engine builder who can tell me what the intake centerline of a A/C cam shaft is!
 
To do anything with cam properly you must first know the intake or exhaust center line. To just state your advancing a camshaft, is taking a shot in the dark. Cams' are phased or degreed in reference to degrees of crank shaft rotation. The valve timing or valve events are phased to degrees of crank shaft rotation. The cam lobes are intended to be timed with crank shaft rotation, so to just state, advance a camshaft is wrong. In order to properly advance or retard a camshaft you must know what the designed lobe center line is and to correctly degree a cam you find out what the lobe center line actually is and then you must correct it by decreeing your camshaft! It doesn’t matter what kind of motor it is a car motor, aircraft, diesel, or air pump their all based on the same principals!
 
Are you sure when he advanced it that he just didn't get it where it was suppose to be in the first place? If the previous builder had the crank and cam timing off, putting it to the proper spot really would wake up that engine. I had an O-200 once that was off one tooth and it ran fine except at high rpm it would drop off. I thought I had carburetor problems and it took me a while to find the timing problem.
 
Here is what I have seen worst case ever was a 540BBC Felber was building the cam was off 12 to 15 degrees yes 15 degrees. Think about whats possible here the key way in the crank can be off a few, the key way in the crank chain gear can be off a few, the cam gear can be off a few then finally the cam dowel or keyway itself can be off a few. As you will see these tolerances can add up quick in either direction so to say I advanced it, your just taking a shot in the dark. You advanced it from where. The cam can still be retarded after advancing it. It's best to just leave it alone unless you phase it properly otherwise your just hoping to get lucky and the motor runs better.
 
Yeah no doubt. The stacking of tollerances can put things way off. Granted...Sometimes that shot in the dark can pay off, and sometimes leavin you with junk. An over advanced cam will build a lot of cylinder pressure, ping it's brains out, and run hot. Too retarded is no sweet deal eaither. Also note that the smaller the cam is duration-wise the easier it will be to put it into detonation, and the bigger the cam is duration-wise the narrower the window is before the engine runs like a turd.

The engine Dave is talking about to my recollection was a 509BBC and it was off over 12 degrees. I've seen quite a few in my day off over 8. And the most common problem I see are people using those 3-position gear sets. They think they're advancing or retarding the cam 4 degrees, but the majority of those lower gears mover the CAM 4 degrees which equates to 8 CRANKSHAFT degrees. So if you don't find your baseline, you're doing nothing more than playing Russian Roulette. Now in defence of an aircraft engine, it's tolerancing may be quite a bit better than OEM Automotive, and the aftermarket, so if we were to presume that the cams were all phased properly from the factory, you may have a much better leg to stand on. JMO

Felber
 
woody":d3ramsvj said:
SO PRETTY MUCH YALL ADVICE IS TO LEAVE THE CAM ALONE,AND PUT 540 RODS IN THE MOTOR
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My advice is to degree the cam to at least know where it is. Then try advancing it a couple degrees and see what the results are. If good, try a little more. If not, try backin it up (retardin it) and see what happens. The main point is to know where you started from before deciding where to go and where you wound up. Cuz after all if you find a sweet combination it would be nice to know how to repeat the process on another engine right?

Felber
 
I've heard of it being done on many 220s ,never tried it on mine and not sure on the gains,from what I heard they use a offset key .I know a well known ac engine builder that did this setup in the past .
 
FELBER AND WATER THUNDER THANKS FOR YOUR ADVICE . MY BUDDY THAT DID HIS,THEY FOLLOWED THE CONTINENTAL BOOK. BUT I AM GOING TO LEAVE WELL ENOUGH ALONE AND INSTALL 0540 BIG JOURNAL ROD IN THE MOTOR. AT LEAST I KNOW THAT WILL DO THE TRICK WITH OUT TRIAL AND ERROR .
 
Just check the ring and piston travel. In some cases that longer rod will push the piston far enough up in the bore that it will go into an area that may have some interference. I guess I'm saying make sure you have a good hone all the way up to the head. I have seen a used jug have a carbon ridge in it and when you add the longer rod the piston will be shoved into this ridge! On some cases people will put a chamfer on the piston edge to clear this.
 
HEY WOODY IT ALL SOUNDS GOOD BUT THE 220 U HAVE NOW WILL DEFINITLY BE A HALF BREED OF A 220 470 540 SO U SHOULDENT HAVE NO COMPLANTS U CAN SAY U HAVE A LITTLE OF ALL

?????? QUESTION TO WT AND FEB WHAT DO U ALL THINK OF ADVACMENT IN THE TIMING ON A CADDIE 500 ME A WOODY ARE ALMOST FINISH WITH THE RIG AND I HAVENT STARTTED THE MOTOR IVE PUT SERVELR TOGEATHER AND NEVER ADVANCET THE TIMING I ALWAYS SET IT AT 0 IM USEING ALL STOCK PARTS BUT THE CAM IS A D/D AIRBOAT CAM FROM CAD COMPANY
 
I have a guy down here that drills the came gear to advance it 10 degrees. Night and day difference... Building another e520 and doing the same again!
 
i always wondered how you would degree a gpu cam.i put an H290 reground cam in my pe-90 conversion and decked it.had to cut a lot off the skirts to clearance them.they hit the inside of the case.them had to trim half moons in the cylinder skirts.didnt like the idea of the 540 rods because they have end play,and decking was way cheaper.ive been told don davis uses a certain dash series 0470 rod that is a bolt in deal.dont remember exactly,-11,-13????????seems redrilling the cam gear would be a crap shoot.regrind at D&S Cams was $125 plus shipping to Edgewater for my four cylinder.good luck.
 
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