What's gud flow for a carb using a syncrometer? Options

[Joe Bob]

Aaron finally sent me my synchrometer....thanks weenie (IMG:http://www.914world.com/bbs2/html/emoticons/pray.gif)

What's a gud flow for each throat at idle? Or do I bump the engine up to 2500 rpms? It's been awhile.... (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif)

I know READ THE FUCHING BOOK....it's at my buddies' shop and he's got his phone off..... (IMG:http://www.914world.com/bbs2/html/emoticons/cool_shades.gif)

[SirAndy]

QUOTE (SEEMORE BUTZ @ Aug 7 2005, 11:28 AM)

What's a gud flow for each throat at idle? Or do I bump the engine up to 2500 rpms? It's been awhile.... (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif)

as i understand it, the actual number is not that important as that will vary from engine to engine ...

i checked all 4, took the highest number i got and adjusted the other 3 to match.

seems to work just fine. but i'm not a carb guy ...
(IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif) Andy

PS: at idle, i did it ...

[rhodyguy]

dearest buttzi, turning the idle up so the engine pulses don't effect the needle will give you a more accurate reading. as andy said, as long as the readings are the same side to side, try the front throats, you'll know you're fairly close. i presume you're dealing with tripple throats. if they have individual air bleed screws, like 40/44idf, you should ensure those are adjusted to a common setting before starting. tomlinson recomends setting them at "one half turn off the bottom" initially.

k

[TimT]

(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif) werd

its not so much the number you see, its that both sides are equal. It does help to raise the idle to 2000rpm or so while you fiddle with the adjustments. When you are done tuning and reduce the idle to 900 or so, double check the settings with the syncrometer.

This post has been edited by TimT: Aug 7 2005, 02:36 PM

[Joe Bob]

Thanks....the air screws on ALL of them are way out from the bottom. Would that contribute to the great gas mileage I have been getting or is it more of a result of my foot flat on the floor boards all the time???
(IMG:http://www.914world.com/bbs2/html/emoticons/cool_shades.gif)

[Trekkor]

QUOTE

the air screws

My understanding is that you start with them ALL the way in as a baseline.

With the throttle linkage disconnected, set the idle to 900-1000 RPM's.

Now, find the fastest pulling cylinder with the sync and adjust the air by-pass screws to raise the draw in each lower pulling barrel.

You'll have to keep lowering the idle, as it will increase with these adjustments. Blip the throttle now and then to keep it from loading up.

After you *think* you are done, put the linkage back on and go around with the sync to check your work.

15 mins (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

Mines held all this time since January.

KT

[Trekkor]

Also, start with the idle needles at 1 and 1/2 turns out from tight.

major thanks go out Perry and Mike Ginter for the help they passed on to me with the Webers (IMG:http://www.914world.com/bbs2/html/emoticons/clap.gif)

KT

[Joe Bob]

Thanks....the air screws were all over the place.....two turns out seems to be the best.

[Joseph Mills]

Mike,

You probably already know this, but maybe someone else can benefit.

Once your idle is balanced with the air-screws, the next step is to adjust the left and right verticle tiny hex-bar linkage that attaches from your carbs to the large horizontal hex-bar. You want to insure the butterflies are opening the same amount for both rows of carbs. Incidently, valves need to be well adjusted and engine warm.

With linkage attached, loosen the locking nuts at both ends of the tiny hex-bar on the passenger side. Now by simply spinning the tiny hex-bar, and using the sync tool to measure by, you can easily increase, or decrease the opening of the butterflies to match those on the drivers side.

Try to get close numeric readings on both banks at 1500, 2000, 2500, 3000rpms. You will have to make repeated adjustments. You'll never get it to be perfect, but you can get it pretty close and it's worth spending some time with at this point, even if you have to walk away from it for a bit. It's a crucial step to eek out a bit of extra performance.

If it turns out that the 1k idle speed is off balance with the syncro tool at this point, don't worry about it.. so be it. You want to make power. You want the engine to pull strong as possible when you accelerate - and it will do so when both banks are balanced thru the acceleration range. You may be able to detect a slightly crisper note when you rev once you achieve it.

I use two syncro tools... makes it way easier and more accurate, but one will work fine too.

[rhodyguy]

aasdf

[Joe Bob]

Just took it on a test/terrorize the 'hood drive. Seems to run a lot better and idle gud....gud accel thru the gears. (IMG:http://www.914world.com/bbs2/html/emoticons/rocking nana.gif)

Also got Frank (356) running this weekend....all I have to do now is finish the gauge rewire and he's ready to twist 356 panties next month at the Ventura autofest. Gonna take the black powder coated wheels off of Red (911 cab) and use them on Frank....that's IF Red gets outta the paint shop next week.....

Work, work, work.... (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif)

[rhodyguy]

mike, are you confusing the idle mixture screws with the air by-pass? the air by-pass helps to equalize any differences in each throat with regards to the butterflys. the diagram in tomlinson's book doesn't show the side of the carbs with those 2 items. the idle air will have a spring. the by-pass looks to have a jam nut only on the needle screw. careful turning those out too far and going way lean.

i tried in vain to up load a scan and got that attachment.

k

[Joe Bob]

I was using the spring loaded ones.... (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

EDIT....meant the idle mixture.....those were the ones cocked up.

[rhodyguy]

it's 8:30 sunday night. i bet your buddy with the manual has a phone that will ring. i think you might atleast have the idle mixture needle valves set the same, but if it runs better go with that.

k

[Trekkor]

Good for man...Good for you.

I thought you might have been confused, too. (IMG:http://www.914world.com/bbs2/html/emoticons/unsure.gif)

Almost called you. (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif)

KT

[rhodyguy]

the springed needle valves are the idle/air mixture screws on the carbs for a 6 right?

k

[Trekkor]

busted out the crayon for ya's (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

[Aaron Cox]

your welcome honey.....

[Joe Bob]

All six ended up pulling 8 mg/h at 950 rpms....just a few spits and coughs as opposed to a LOT before...it ended up just being the idle mixtures being off....