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"Head clearance at .009" (but taking a plug out every other run)"

Believe it or not, when I got the MAC21 head clearance down to .006" and the FAT21 pipe below 7 1/2" it stopped taking out plugs every couple runs. :)
 
Rick,

What Don says is right on the money. It doesn't make sense, at first, until you look at it like this: If you have too much head space, you have to lean down on it too much to get it to come alive, because of no torque. When it does come alive, it is set way too lean and smokes the plug. If you get the head clearance down to, oh, I don't know...... Let's say....... Just to pick a number.......... Somewhere around .006" or so......... :rolleyes: You get alot more torque and it will launch better and climb the pipe much easier on a richer mixture. Your plugs last alot longer and you go faster to boot.

I know sometimes it tough following the advice you've asked for, but sometimes you've just gotta trust someone. Do what you've got to do to get the head space down to .006" and see what happens. It's real easy: If you don't like what you get, you can always add shims.

Thanks. Brad.

Titan Racing Components

BlackJack Hydros
 
Rick,
What Don says is right on the money. It doesn't make sense, at first, until you look at it like this: If you have too much head space, you have to lean down on it too much to get it to come alive, because of no torque. When it does come alive, it is set way too lean and smokes the plug. If you get the head clearance down to, oh, I don't know...... Let's say....... Just to pick a number.......... Somewhere around .006" or so......... :rolleyes: You get alot more torque and it will launch better and climb the pipe much easier on a richer mixture. Your plugs last alot longer and you go faster to boot.

I know sometimes it tough following the advice you've asked for, but sometimes you've just gotta trust someone. Do what you've got to do to get the head space down to .006" and see what happens. It's real easy: If you don't like what you get, you can always add shims.

Thanks. Brad.

Titan Racing Components

BlackJack Hydros
Even being an old dog I am as well learning that proper head clearance is crucial to avoiding detonation . The elimination of "useless " space out toward the edge of the combustion chamber , actually reduces the likelyhood of uncontrolled combustion (detonation )in our engines . For years I have been running motors as they come from the manufacturer figuring they had it all worked out ......but it's not that simple some times .

On the subject of launch ...sometimes the smaller motors will have to be richer to "climb " out of the hole and get on top at partial throttle rather than wide open . a lot of things at play with the smaller motors , learning every day !!!!
 
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Well, I'm here to report everyones suggestions about head space, pipe length and set up must be working

Came home with a 1st place trophy for the weekend at the Melbourne race, in some very adverse conditions.

Even "Too Fast Foley" said it looks like we have it well on it's way.

I am looking forward to this new (to me) class, had fun with it this weekend

Just wish I could justify the 4 hour trip to the other side of the state for a 1 day race, so I could run with Marty, and Rod Hendrick's.

Again, thanks folks
 
Well, I'm here to report everyones suggestions about head space, pipe length and set up must be workingCame home with a 1st place trophy for the weekend at the Melbourne race, in some very adverse conditions.

Even "Too Fast Foley" said it looks like we have it well on it's way.

I am looking forward to this new (to me) class, had fun with it this weekend

Just wish I could justify the 4 hour trip to the other side of the state for a 1 day race, so I could run with Marty, and Rod Hendrick's.

Again, thanks folks
Rick, congrats on your win. Could you share your race setup? Thank You, Richard D
 
Well, I'm here to report everyones suggestions about head space, pipe length and set up must be workingCame home with a 1st place trophy for the weekend at the Melbourne race, in some very adverse conditions.

Even "Too Fast Foley" said it looks like we have it well on it's way.

I am looking forward to this new (to me) class, had fun with it this weekend

Just wish I could justify the 4 hour trip to the other side of the state for a 1 day race, so I could run with Marty, and Rod Hendrick's.

Again, thanks folks
Rick:

I also wish that you could come to this reace. We have a GREAT pond and I would like to race with you in your new class.
 
"Head clearance at .009" (but taking a plug out every other run)"
Believe it or not, when I got the MAC21 head clearance down to .006" and the FAT21 pipe below 7 1/2" it stopped taking out plugs every couple runs. :)

Don is EXACTLY correct about closer head clearance stopping plug burning.

The reason is simple. When you have the squish band where it belongs (.006") the engine makes maximum HP. That makes it much easier for the engine to do the work. It doesn't have to work nearly as hard to pull the big prop. Same thing with nitro. When you have a lot 65-70% the engine makes maximum HP and the engine does not have to work nearly as hard. The needle can be much richer which makes the engine run cooler (the fuel mixture is the main coolant for the engine).

Actually the engine will last longer since it is not having to work nearly as hard. Bearings last longer because of richer fuel mixture, etc etc.
 
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