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BROKEN RECORD

1K views 8 replies 5 participants last post by  4 Jaw Chuck 
#1 ·
DONT MEAN TO SOUND LIKE ONE BUT IM STILL TRYING TO FIND OUT WHY MY HEADERS GLOW. LETS SAY YOU BOUGHT A CRATE MOTOR AND YOU TURN IT 5000. ITS A 350 WITH A DUAL PLANE 600 VAC SEC. YOU NOTICE YOUR HEADERS GLOW OFF THE HEADS. NO HESITATION AND THE SPARKPLUGS LOOK GOOD. TIMED AT 32 DEGREES TOTAL ADVANCE. NOW THE ONLY CHANGES I MADE WAS PUTTING A SINGLE PLANE WITH A 750 DBL. PUMPER. THEY STILL GLOW AND THE PLUGS STILL LOOK OK. OK SO MAYBE #5 AND # 6 LOOK A LITTLE WHITER THAN THE REST ITS NOT A BURNT WHITE ITS MORE LIKE BRAND NEW WHITE WHICH I HEAR IS PERFECT. PAPERBAG BRN ON THE REST UNLESS I IDLE FOR A WHILE WHICH WILL SUIT THEM UP A BIT BUT NOT FOWL THEM. IM OK TO LEAVE IT JUST DONT WANT TO BE DAMAGING THE MOTOR INSIDE OR RUN MY PISTONS TO HOT. ITS ON AN AIRBOAT SO ITS EASY TO MONITOR A NIGHT. I DONT THINK ITS TO LEAN AND IF I JET DOWN ILL PICK UP HESITATION. THANKS FOR ANY ANSWERS. BERN
 
#3 ·
I USE A REDUCER INSTEAD OF A THERMOSTAT SO MY TEMP IS AROUND 130 IDLE AND 150 RUNNING SPEED. NO I HAVENT CHECKED THE INTAKE BOLTS BUT I WILL. WHAT ELSE COULD IT BE. USING CERAMIC COATED STAINLESS HEADERS, LONG TUBE, 1 3/4 DIAMETER TUBES 3 INCH COLLECTOR, THANKS BERN

[ October 14, 2002: Message edited by: BERN ]</p>
 
#6 ·
An airboat engine works under some heavy duty conditions and mostly under full load, what your seeing is normal if you have ever shut the lights out in a Dyno room before. If it bothers you fabricate thicker pipes or use cast iron manifolds, if your plugs are not eroding and the color is good then don't mess with it. Stainless valves are a recommended mod for the conditions you run that engine in. Remember cherry red is Ok but orange is valve melt temperatures. Is your prop the right size? Pitch? What rpm do you cruise at? Gearbox (if any)? Open or muffled exhaust? Give us some more info on your setup.
 
#7 ·
If you don't want to richen the intake mixture (fuel is also a coolant), I would merely monitor the plugs for a few weeks (signs of heat detonation-small deposits of aluminum-do you have aluminum pistons?). Maybe use a boroscope to view the piston tops/valves.

If you see no deposits after a week or so, I would assume what you are seeing is normal.
 
#8 ·
4-jaw- prop and gear box are perfect match for motor rpm. motor turns 5000 with a 2.12:1 gearbox ratio turning a 78" powerplus power shift which turns 2480 rpm's, right where it wants to be. sometimes open headers and some times 3-4 foot of flex pipe. i have tried jetting up and down but pick up hesitation either way. i cruise around 2800-3000 rpm's. it does glow from 2800 and up. more the higher. at two inches from the head it looks kinda orange to me. it starts on the center holes and spreads out to the corner holes. i have blueish flames coming out of straight headers about 6". will i melt my valves one day.
 
#9 ·
Nah, sounds normal. A set of those header mufflers will cork it up a bit and will add some torque at the rpm your running it now, open headers do make the tuning sensitive to atmospheric conditions and mufflers will moderate this somewhat. That must be one heck of a racket at WOT! Woo Hoo! No gator will miss hearing you! Must sound like the entire Nascar line up from Talledaga coming down the river! :D
 
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