Motorsports Village

Should I just go ahead and put the 26 bleeds in now? Or should I make another pass first with my current stuff then throw them in, and check the plugs?

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74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft

Here is my last run from sunday, was on the brakes at the end, but this would have been a 10.66 pass. I started out with a 10.78, then a 10.75
that was around 12.30 then by the end of the day, 5:30 was the last pass, the humidity had dropped to around 63% compared to 90% with those first runs and the bar came up a little too from 29.70 to 29.78.

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74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft

Well Did not get to check plugs was just way too many damn cars for the last day again. I did however make two runs with my last setup from last week no changes, then my 3rd pass i changed the air bleeds to 25.5's from the 24.5's measured with my caliper's. It leaned it out just a tad to closer to 13.3-13.4 range. The car on the 1st run only ran 123.78, second run it spun and ran more mph 124.33, 3rd run with bleed change it went 124.30. So I will throw out that second pass cause it spun and compare it to my first pass and it picked up mph. I will leave it has is now til spring when i can check some plugs. My guess is it liked it, just by watching the mph go up.here are the two runs, the 1st and the 3rd which is the bleed change. let me know what ya think.

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74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft

Session 3 is a good airbleed setup, it may need some main jet adjustments but it will require fine tolerance main jets not ordinary ones.

Thanks,The car felt kinda flat on that first run yesterday, but after the bleed change it seemed to pull harder , smoother? It was only a 1/2 hr difference between 1st and 3rd run. So your saying if this chart were to be the same as what the plug is seeing , Which I don't know yet, then i would need to pin these jets and then get just barely bigger ones to bring down that line just a tad?

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74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft

Holley make fine tolerance main jets for emissions. Look in the catalog. I think each jet steps 1/3rd of what the steps are in the ordinary jets.
An alternative to jetting is to lift the float level a flat on the nut or up the fuel pressure quarter or half a pound at a time. The fuel pressure will hold the bowl level higher as you go down track. Its all ways of fine adjusting. Or a slight reduction in the IAB will enrich the top end too.
Or you can modify main jets by making them shorter and then they flow slightly more. Or radius them.

Interesting about the IAB's. I thought they did not effect WOT? I found this last week any truth to this? This guy swears that its good for .03-.08 in E.T. Post number 2. FWIW I did this for the last race, but i also closed off the PVCR'S too like Ken talked about.

http://www.yellowbullet.com/forum/showt ... p?t=411970

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74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft

The IAB's effect WOT. The transfer circuit should flow fuel all the time. Smaller IAB will richen the running slightly while on the t-slot but it will enrich the engine at WOT too.
Its only when you make the IAB and IFR way too small that you get reverse air flow up the T-slot at WOT. Your nowhere near that.

That kind of makes sense, a bit more unrestricted fuel flow...Honestly I don't know where mine are
pointed ..

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running E85
Best ET 8.07
Best MPH 170.71
Barry

What he says in that link about the positioning of the N&S is correct BUT it doesnt cause foaming. It does restrict the flow a little bit though. I did that testing decades ago and if I remember right it flowed 50hp less methanol with the N&S turned sideways to the inlet.
Its not a problem you need to bother with.

Anyone here besides me don't know where there N&S window is pointing???
Funny how all the carb stuff here no one ever said anything about this that I could
remember anyway ..

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running E85
Best ET 8.07
Best MPH 170.71
Barry

Okay, cool, well I put the car away yesterday for the year. I will probably try some .060's in the IAB I have .063's now for next spring, going to be a long winter if we dont get snow to play with my 140 hp sled :)

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74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft

More I think about that statement is that you can only turn that adjusting nut a half turn either way then to make sure everything lines up again...So with that statement then there is no "flat" adjusting only 1/2 turn??? I can also see where there is a restriction there is usually foaming of some sort..

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running E85
Best ET 8.07
Best MPH 170.71
Barry

Just to add to this I set my floats with a 7/16 drill bit and that window was damn close if not right on. That is using the BLP blocks with the big holley site glass half way up it like it says in the instructions for the new ultra doms from holley.

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74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft

The pressure is both sides of the window, the needle is the pressure restriction point so the fuel thats passing the window isnt open to atmosphere, its under pressure, it doesnt foam at that point. If you adjust the window half a turn you alter the level etc and it slightly alters the flow rate but on gasoline its nothing. It caused the result I said in my tests at MAximum flow on Methanol,It was 900hp worth from ONE bowl. You cant race like that anyway because the fuel would be at the bottom of the bowl and its basically running dry.I dont know anyone who runs an 1800hp engine on Methanol on a single carby. Dont bother about it. A car will change performance with a float level change, whether you go up or down and finish up with the window crossways to the flow is irrelevant.
Foaming comes from fuel spraying into the bowl just like spraying a hose into a bucket and mucking around with your finger on the hose end playing with the water velocity. Use bigger N&S and lower fuel pressure and it reduces foaming.