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correct procedures for tunning or the ten mistakes we make learning curve bbc natual asperation
 

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correct procedures for tunning or the ten mistakes we make learning curve bbc natual asperation
The best thing you can do is put it on a dyno

The data on the dyno can spot trouble spots in power curve

And establish base line performance levels

Once tuned and jetted correctly,@ those Air temp,baro, relative humidity.

There are jetting formulas to correct for air changes you will experience during the season or altitude you boat at.
 

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Can you elaborate on the formula Steve. Mine was alittle fat on the dyno(done in February) and is alittle lean out on the river in the summer time.
Thanks
 

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Can you elaborate on the formula Steve. Mine was alittle fat on the dyno(done in February) and is alittle lean out on the river in the summer time.
Thanks
Sure I can
I bought a autographed book, from forum member -Inquisitive Gearhead
He wrote the book On the Dyno packed full of information,Tuning tips on weather conditions, i.e. baro pressure, wet and dry bulb temps, and putting it together to get a correct fuel factor going in to the motor with a given oxygen content of air
He has done much of the hard work on Psychometric charts and conversions tables. This is the key to understanding correction factors CF on the Dyno

I would give him a PM
Its a excellent resource book
Big Steve
 

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Absolutely no reason that you couldnt use an O2 sensor setup with datalogging capabilities and just tune it on the lake in the exact enviroment that it will be operated in. They are very inexpensive today and can be setup with a warning light that will tell you if you are getting lean anywhere in the run. An LM2 with these capabilities is under $300 on E-Bay . It also can datalog 5 more channels if you choose to watch boost, oil pressure, intake pressure,rpms,fuel pressure, nozzle pressure, ect. But you have to purchase the transducers just like with any other datalogger.JMO.
 

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Can you elaborate on the formula Steve. Mine was alittle fat on the dyno(done in February) and is alittle lean out on the river in the summer time.
Thanks
If your engine was lean at the river in the summertime..... it was not rich on the dyno in the winter....... unless you dynoed on top of a mountain and ran the engine in the boat in a low valley..... ..
 

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If your engine was lean at the river in the summertime..... it was not rich on the dyno in the winter....... unless you dynoed on top of a mountain and ran the engine in the boat in a low valley..... ..[/QUOTE

True enough!!!
 

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Plugs look alittle on the lean side After a pass Gear And of course my dyno session was junk :cool:

Gonna start fresh come springtime and get her dialed in
 

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Plugs look alittle on the lean side After a pass Gear And of course my dyno session was junk :cool:

Gonna start fresh come springtime and get her dialed in
The constant load of a jet on the lake likes fuel;) Don't be timid about adding more while watching your tach, plugs, gps and time slips. It will show you what it wants:)

Gear
 

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The constant load of a jet on the lake likes fuel;) Don't be timid about adding more while watching your tach, plugs, gps and time slips. It will show you what it wants:)

Gear
Yeah, and if you dont pay attention, it'll show you what it dont want. :)grn
 

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The constant load of a jet on the lake likes fuel;) Don't be timid about adding more while watching your tach, plugs, gps and time slips. It will show you what it wants:)

Gear


No time slips but i can do everything else .. I had these carbs on a 468 and then put them on the 540 and took it to the dyno .. Dyno man said I was alittle on the fat side, witch I like, but we never pulled a plug to have a look :knockout:.. I always liked to see alittle black on the back of the boat at the end of the day and noticed when I would go out it was clean so I pulled a few plugs after a pass and noticed they looked alittle lean .. I'm gonna go up a few jet sizes until i get the plugs looking better :happy:


FWIW
BBC 540 runnin on 93
2 QF 750s
Primary jets 72
Secondary jets 84
Power Valve 4.5

Boat runs great at mid RPM range and at WOT.. I'd just like to get a little fatter tune on it :dunno:
 

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what ignition system?

I WAS running a pump gas 9.3 comp. n/a 540 w/2 850s and a msd ignition. i was told reading the plugs when running the msd, that you look at the threads of the plug not the electrode. The msd has such an efficiant fire that it will burn the carbon off the electrode. I was told that w/msd that around 3-4 threads from the end of the plug should have a little color change (slight carbon). My header pipes were a very light chocolate color at the end of the collectors, some days it would be white to light gray (like race fuel) depending on air temp and quality.
 

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Can you elaborate on the formula Steve. Mine was alittle fat on the dyno(done in February) and is alittle lean out on the river in the summer time.
Thanks
how fat is fat on the dyno? what were the a/f numbers at WOT and do you have them for each cylinder or just from a collector?

And how are you determining that its lean in the summertime?

If it truly is lean, it could be due to the exhaust and/or fuel system in your boat, if you didn't tuen the engine with those exact parts on the dyno.
 

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No time slips but i can do everything else .. I had these carbs on a 468 and then put them on the 540 and took it to the dyno .. Dyno man said I was alittle on the fat side, witch I like, but we never pulled a plug to have a look :knockout:.. I always liked to see alittle black on the back of the boat at the end of the day and noticed when I would go out it was clean so I pulled a few plugs after a pass and noticed they looked alittle lean .. I'm gonna go up a few jet sizes until i get the plugs looking better :happy:


FWIW
BBC 540 runnin on 93
2 QF 750s
Primary jets 72
Secondary jets 84
Power Valve 4.5

Boat runs great at mid RPM range and at WOT.. I'd just like to get a little fatter tune on it :dunno:


black on the tansom is not necessarily and indicator that the engine is running fat at WOT. that's likely from idling or part throttle operation. And unless you are making a pass with brand new plugs and shutting the engine off immediately after and pull the plugs to look at them, you are not getting a proper plug reading. lots of guys mistake a sooty looking plug as the engine running fat when it really isn't because they've been driving all over the lake before pulling the plug to check it.
 

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I WAS running a pump gas 9.3 comp. n/a 540 w/2 850s and a msd ignition. i was told reading the plugs when running the msd, that you look at the threads of the plug not the electrode. The msd has such an efficiant fire that it will burn the carbon off the electrode. I was told that w/msd that around 3-4 threads from the end of the plug should have a little color change (slight carbon). My header pipes were a very light chocolate color at the end of the collectors, some days it would be white to light gray (like race fuel) depending on air temp and quality.
that's not exactly true. Any good ignition system will cook the coating off the ground strap. A NGK is easier to read than others like Autolite. What you want is the coating cooked off from the end of the strap until right at the bend or just before it. If the coating cooks off past the bend and on down to the plug threads then the ignition is likely too far advanced.

And unless you have a plug magnifier and can look down at the bottom of the porcelin at the fuel ring, its really difficult to tell whether the engine is running fat or lean. You can't tell by looking at the top of the porcelin.
 

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that's not exactly true. Any good ignition system will cook the coating off the ground strap. A NGK is easier to read than others like Autolite. What you want is the coating cooked off from the end of the strap until right at the bend or just before it. If the coating cooks off past the bend and on down to the plug threads then the ignition is likely too far advanced.

And unless you have a plug magnifier and can look down at the bottom of the porcelin at the fuel ring, its really difficult to tell whether the engine is running fat or lean. You can't tell by looking at the top of the porcelin.
Finn is dead on. The type of ignition is a minor player. Plugs from mags look a little different, but for tuning purposes, pretty much the same.
The side strap(electrode) is an inticator of your timing, the thread count discolorization will help indicate the plugs heat range, and the color ring at the base of the ceramic,(refered to as porcelin) is the only way to read the AF. All this is based on a WOT, full RPM, with a quick shut off.

Hands down the best way to read the color ring is to cut the plug, but a plug magnification scope will suffice.
This is what you looking for.




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that's not exactly true. Any good ignition system will cook the coating off the ground strap. A NGK is easier to read than others like Autolite. What you want is the coating cooked off from the end of the strap until right at the bend or just before it. If the coating cooks off past the bend and on down to the plug threads then the ignition is likely too far advanced.

And unless you have a plug magnifier and can look down at the bottom of the porcelin at the fuel ring, its really difficult to tell whether the engine is running fat or lean. You can't tell by looking at the top of the porcelin.
Finn is dead on. The type of ignition is a minor player. Plugs from mags look a little different, but for tuning purposes, pretty much the same.
The side strap(electrode) is an inticator of your timing, the thread count discolorization will help indicate the plugs heat range, and the color ring at the base of the ceramic,(refered to as porcelin) is the only way to read the AF. All this is based on a WOT, full RPM, with a quick shut off.

Hands down the best way to read the color ring is to cut the plug, but a plug magnification scope will suffice.
This is what you looking for.
This is the best econo plug reader I've used. The light and magnification are perfect for reading plugs when you can't cut the threads off if them.
http://www.drmomotoscope.com/#product
 

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I've read that if you can't do a clean cut off, then the base of the porcelin(ceramic) will still give you a good indication of the tune. The tip is more of the idle tune.

Tim
The base is where you'll look for the a/f at WOT. A thin, almost non-existent fuel ring at the bottom of the porcelain is a good tuneup. The darker and thicker the ring the fatter the engine is.

Contrary to popular belief, a fat tuneup is not necessarily safer and doesn't make more power. many engines make best power and require the least amount of timing advance at 12.5-12.8 a/f ratio.
Don't get too hung up on what your header collectors or transom look like. Those are not good indicators of the engines running condition. Read the plugs and give the engine what it wants in terms of timing and fuel. Unless you can datalog the a/f on a dyno or in the boat at the track with clocks it will be tough to determine the exact right a/f ratio for your engine that makes the most power without detonating. you can certainly get close though.
 

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how fat is fat on the dyno? what were the a/f numbers at WOT and do you have them for each cylinder or just from a collector?

And how are you determining that its lean in the summertime?

If it truly is lean, it could be due to the exhaust and/or fuel system in your boat, if you didn't tuen the engine with those exact parts on the dyno.



Not real sure Mike, I've only been to 1 dyno session and it was a kinda jacked up session, not a good 1st timers learning experience.. He was only pulling data from 1 carb and I believe from the collector .. The dyno op told me that I was alittle on the fat side but when I was out on the river and I made a pass, shut it down and pulled a few plugs they were alittle on the gray side .. Not white, but alittle gray !!!! I'm running 32* timing and according to the dyno that is what the engine liked .. Here is a copy of the dyno session




Thanks for the help guys !!!!
 
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