Exhaust/cyl head temps??

[STEVE FRENCH]

Finally rig'n my Digatron to my 25MOD OMC......Had a melt-down last Spring at Franklin with my Nationals motor after going to CDI ignition......was just get'n on plane and bottom cyl aluminum fouled plug....
Talked to Carl Staron and he advised drop'n timing to .280 BTDC (was .350 w/points) and start over test'n.

first time out I was see'n 1150 on exhaust (probe in elbow about 1 1/2" from port) and 220 on head (sensor under spark plug) ....plugs were tan.

any thoughts?

19P

[brian]

Aluminium :


Melting Point: 660.37 °C or 933.52 K or 1220.666 °F)

70 degress to spare.....

[sax]

Steve.....check this link out for EGT use.

http://www.foxvalleykart.com/egt.html

[johnsonm50]

Is 0.350 at or about the same as a stock 22ci OMC at full advance w/point condenser ignition? Was the specific meltdown the fouled plug or further trouble?

[STEVE FRENCH]

Is 0.350 at or about the same as a stock 22ci OMC at full advance w/point condenser ignition? Was the specific meltdown the fouled plug or further trouble?

Way beyond stock.........kicks like a mule start'n.......
But hard to keep points set and condencers literally shake apart unless you gob/cap the wire end with silcone sealer.

Going to CDI for reliabillty/low maint only.....Just gott'a git it dialed in.

With the CDI...spark is faster/hotter? and less advance needed.....hence deflector started to flake/melt gett'n on plane and fouled plug with alum.
went back to point/condensor motors for rest of 2007.

Now 2 new pistons and little test time......back with the CDI and Digitron DT-46K.
Read'ns in first post were with a fixed expansion chamber from our 44Merc and probably a factor on temp read'ns........chamber had NO raceable low end and now back to Bayer megaphone......chamber might work on a long KILO run cause it pulled like a freight train once on-the-pipe...just took half the lake to get'er go'n....wanted to test 1X1 foot/props and hold noise down at local lake and avoid tar/feathers when back to boat ramp..........

Also gonn'a go from a .072 to a .076 jet and see if it stays clean in corners and watch EGT ....Then I guess it's play with time'n time..................

Sax, thanks for th link!

Steve.....check this link out for EGT use.

http://www.foxvalleykart.com/egt.html

19P

[johnsonm50]

Thanks, Ive been playin with a B mod OMC 22, just put a CDI on and barrel ran for a few seconds. Looks like alot of on water test time needed, too dang loud to do it here tho... neighbors =

[STEVE FRENCH]

Thanks, Ive been playin with a B mod OMC 22, just put a CDI on and barrel ran for a few seconds. Looks like alot of on water test time needed, too dang loud to do it here tho... neighbors =

How are you time'n your's?.....I used a dial indicator and marked flywheel at TDC/.250/.280 BTDC.....using crankcase split for reference.....used 1/2" drill and timing light and have sailboat rig'n-turn buckle to adjust.

LOL on BMH class....especially if ya start win'n............... ...If ya smell hot tar...RUN!

19P

[Skoontz]

Steve:

Do you find a better reading with the exhaust probe that far off the port? I've always kept ours at a bout a 30° to the top port between the first and second spacer bar. My thoughts were to get the probe as close to the internal parts making heat as possible, not to give the gas a split second to cool down....

Any thoughts?

[Mike 41P]

25omc

Here's what I've seen with mine
I had exh temp as high as 1300 with 72 jet
went larger to cool it down
ER said stay below 1200
with CD ign I time with light to about 32 deg
look around and you can find the newer CD flywheels that have degree scale
or measure off one, I just make marks for 25/30/35 on the older ones
Mike T

[STEVE FRENCH]

Here's what I've seen with mine
I had exh temp as high as 1300 with 72 jet
went larger to cool it down
ER said stay below 1200
with CD ign I time with light to about 32 deg
look around and you can find the newer CD flywheels that have degree scale
or measure off one, I just make marks for 25/30/35 on the older ones
Mike T

Mike if you git time,...put a dial indicator in yours and see what 30/32/35 degrees is compaired to .250-.300 BTDC?....mean while I'll look for a newer flywheel to do same........since I know were your motor came from,..it should be pretty well dialed in!.........would of been interest'n at Franklin last year in BMH if not for spin!

Do any of the Digatrons have the abillity to display CHT and EGT at same time?

Thanks,
19P

[Brian10s]

Digatron

Steve,
I think the 50 series will do all 3 (rpm, cht & egr).

http://www.digatronusa.com/products-boats.shtml

[johnsonm50]

How are you time'n your's?.....I used a dial indicator and marked flywheel at TDC/.280/.300 BTDC.....using crankcase split for reference.....used 1/2" drill and timing light and have sailboat rig'n-turn buckle to adjust.

LOL on BMH class....especially if ya start win'n............... ...If ya smell hot tar...RUN!

19P

To get it started in a barrel I measured/marked 30 degrees. It started instantly. [no tar so far]

[johnsonm50]

Mike if you git time,...put a dial indicator in yours and see what 30/32/35 degrees is compaired to .250-.300 BTDC?....mean while I'll look for a newer flywheel to do same........since I know were your motor came from,..it should be pretty well dialed in!.........would of been interest'n at Franklin last year in BMH if not for spin!

Do any of the Digatrons have the abillity to display CHT and EGT at same time?

Thanks,
19P

Steve, Im guessin thats an AB foot, is the skeg sometin you did?