Jerry Wyss
Well-Known Member
- Joined
- May 3, 2004
- Messages
- 3,139
Nitrolizer, If the engine is already broken-in running full water then you'll have to live
with that unless you re-size the sleeve or slightly increase the piston crown area
diamiter by several methods.
Those methods have been presented here over the last couple years, I use the small
copper pipe tubing cutters (very small) in the upper oil groove or between the oil
groove and the top of the piston.
I'm a plumber, so I have cut tons of copper pipe over 28 years and after cutting
copper pipe(with a wheel cutter) you will have a "flare" on the seperated ends you
just cut. This flare will oftentimes will have to be sanded down so the pipe will go into
the fitting.
Well, in the pistons case you obviously don't cut all the way in-two, just enough to
make a line in the aluminum which will also create a small flare on each side of the
cut line. The oil groove is the "next best" place to do this but usually it's too far down
from the piston crown, so it's less effective there.
Two words of caution, The right tubing cutter's and it don't take much to flare it
allot, making the fit VERY tight.
With that accomplished, then you can pull the water off and run it rich to break it in
all over again. With a nickle sleeve the break-in will take several tanks of fuel.
On my O.S.30VG-P-X truck engine (on a Thunder Tiger lower)I ran at least 12 tanks
of fuel at a needle setting that initially allowed the boat to go only 20 mph.
As the engine broke-in it went faster and faster with the same needle setting but
it took many,many boring runs. The O.S.30VG is aircooled with the stock head
cut-down to three fins and reduced in diamiter from stock.
On the other side, I have broken-in 2 heavily modified Thunder Tiger .21O/B
engines with the water totally off from the beginning with the stock water
head cap in place. As I found out I can get away with this in the winter months
around here with unbelievable perfomance gains. The key is to run it very rich,
so rich that the boat just putt's around the course for several laps. At some
point you will hear the engine start to rev-up a little in the corners, and then
all of a sudden it will take-off with a velocity that's staggering!
I haven't got it worked out totally for consistant heat racing starts, but for
a "WOW" factor in practice, It's quite Thrilling.
Where you live, this might be something you might want to explore, but some more
words of caution, if your too lean, like the boat takes off right from launch, just
turn around and bring it back in and richen it up.
I have got close to lean a couple times where it took off after a couple laps but
would soon lay down at the ends of the straight 2 or 3 laps later,, bring it in quick.
On those two occasions the MC59 silver finish plug body turned "blue" from the heat,
now thats got to be well over 600 degrees F to do that,,with no noticable damage
to the engine. The engine continued to run strong for 3 months of testing and well
into the racing season. But like I said above, the summer months required a change
to an aircooled head to get a little more cooling.
JW
with that unless you re-size the sleeve or slightly increase the piston crown area
diamiter by several methods.
Those methods have been presented here over the last couple years, I use the small
copper pipe tubing cutters (very small) in the upper oil groove or between the oil
groove and the top of the piston.
I'm a plumber, so I have cut tons of copper pipe over 28 years and after cutting
copper pipe(with a wheel cutter) you will have a "flare" on the seperated ends you
just cut. This flare will oftentimes will have to be sanded down so the pipe will go into
the fitting.
Well, in the pistons case you obviously don't cut all the way in-two, just enough to
make a line in the aluminum which will also create a small flare on each side of the
cut line. The oil groove is the "next best" place to do this but usually it's too far down
from the piston crown, so it's less effective there.
Two words of caution, The right tubing cutter's and it don't take much to flare it
allot, making the fit VERY tight.
With that accomplished, then you can pull the water off and run it rich to break it in
all over again. With a nickle sleeve the break-in will take several tanks of fuel.
On my O.S.30VG-P-X truck engine (on a Thunder Tiger lower)I ran at least 12 tanks
of fuel at a needle setting that initially allowed the boat to go only 20 mph.
As the engine broke-in it went faster and faster with the same needle setting but
it took many,many boring runs. The O.S.30VG is aircooled with the stock head
cut-down to three fins and reduced in diamiter from stock.
On the other side, I have broken-in 2 heavily modified Thunder Tiger .21O/B
engines with the water totally off from the beginning with the stock water
head cap in place. As I found out I can get away with this in the winter months
around here with unbelievable perfomance gains. The key is to run it very rich,
so rich that the boat just putt's around the course for several laps. At some
point you will hear the engine start to rev-up a little in the corners, and then
all of a sudden it will take-off with a velocity that's staggering!
I haven't got it worked out totally for consistant heat racing starts, but for
a "WOW" factor in practice, It's quite Thrilling.
Where you live, this might be something you might want to explore, but some more
words of caution, if your too lean, like the boat takes off right from launch, just
turn around and bring it back in and richen it up.
I have got close to lean a couple times where it took off after a couple laps but
would soon lay down at the ends of the straight 2 or 3 laps later,, bring it in quick.
On those two occasions the MC59 silver finish plug body turned "blue" from the heat,
now thats got to be well over 600 degrees F to do that,,with no noticable damage
to the engine. The engine continued to run strong for 3 months of testing and well
into the racing season. But like I said above, the summer months required a change
to an aircooled head to get a little more cooling.
JW
Last edited by a moderator:
On the exit I got a piece of fuel tube and opened 3 tiny holes about 1mm away from each other and plugged the hole with a round stick.... You can then slide the stick to have 1, 2 or the 3 holes uncovered for more or less water flow. The holes I made spinning the tip of a exacto knife on the fuel tube... they are very small... can't even see thru them...
