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 Post Posted: Mon Aug 22, 2011 5:29 pm 
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CarbGuy wrote:
It also eliminates issues with vibration causing a rich condition from working the pumps.



Hey Doug,

If you willing to share, do you modify the stock cam at all? What is the typical size you use for the bleed?

Thanks

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 Post Posted: Tue Aug 23, 2011 9:01 am 
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fourtenposi wrote:
Hey Doug,

If you willing to share, do you modify the stock cam at all? What is the typical size you use for the bleed?

Thanks


Yes we will modify the stock cams on certain engine combinations, but honestly we'll do as much to tune with the linkage geometry and drivers style as we do for getting the engine to respond properly.

As far as the bleed goes, it all depends on the application I've been as small at .007" and as large as .093".

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 Post Posted: Tue Aug 23, 2011 11:31 am 
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When you say linkage geometry, are you referring to the progression between the barrels or are you referring to playing with the ratio between the gas pedal input vs the throttle movement?

I can say after trying some different things, there is definitely a preferred feel that I am looking for that I feel benefits me footbraking.

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 Post Posted: Tue Aug 23, 2011 11:43 am 
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fourtenposi wrote:
When you say linkage geometry, are you referring to the progression between the barrels or are you referring to playing with the ratio between the gas pedal input vs the throttle movement?

I can say after trying some different things, there is definitely a preferred feel that I am looking for that I feel benefits me footbraking.



Both, as changes in both of them will affect how much throttle is used, and how quickly it rotates which will affect the need for accelerator pump shot.

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 Post Posted: Tue Aug 23, 2011 11:56 am 
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Interesting point, I will have to let that one sink into the brain a bit.

I have noticed on mine, that it seems to need a little more pump shot down low when I roll into the throttle to come up to my staging rpm, and it doesn't seem to need much at all going to WOT from launch rpm.

Thanks for your input and perspective.

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 Post Posted: Tue Aug 23, 2011 1:02 pm 
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FWIW I had a ProSystems 4150 That had the accel pump bleed in the metering blocks. It was where the pumpshot exited the the metering block prior to entering the the main body. The hole was right where the passage from the pump joned the exit passage. Excess fuel passed back into the fuel bowl. Both metering blocks had this hole which was about .030 I think. This carb had a 50cc pump in front and a 30cc in the rear.

Until this moment I thought they were a bleed to prevent pull over from the discharge nozzles. Go figure. Not sure how all of this will affect delay box cars or those on throttle stops and SLEs. I guess I got some drilling to do as this mod can be reversed if it doesn't work for me..


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 Post Posted: Tue Aug 23, 2011 5:06 pm 
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I actually though about putting it there, but I was worried that it would be really close to the fuel level and that potentially could suck air there. May have been a non issue, but that is why I choose to put it down in the float bowl.

BTW, my deployment got cancelled, so there will be more testing for me!

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 Post Posted: Tue Aug 23, 2011 6:05 pm 
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nomad wrote:
FWIW I had a ProSystems 4150 That had the accel pump bleed in the metering blocks. It was where the pumpshot exited the the metering block prior to entering the the main body. The hole was right where the passage from the pump joned the exit passage. Excess fuel passed back into the fuel bowl. Both metering blocks had this hole which was about .030 I think. This carb had a 50cc pump in front and a 30cc in the rear.

Until this moment I thought they were a bleed to prevent pull over from the discharge nozzles. Go figure. Not sure how all of this will affect delay box cars or those on throttle stops and SLEs. I guess I got some drilling to do as this mod can be reversed if it doesn't work for me..



Typically pullover is cured with a couple small holes in the nozzle itself.

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 Post Posted: Wed Aug 24, 2011 7:29 pm 
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Do you typically set the front and back up the same as far as squirter bleeds/pumps?

With the progression that mine has, I was thinking of just reducing the size of the bleed up front and leaving the rear bleed alone. My rear barrels don't start to kick in till 4000 rpms and footbraking I launch at 3000 rpms. The should hopefully give it that extra fuel that it needs as I slowly roll into the throttle to launch rpm.

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 Post Posted: Thu Aug 25, 2011 11:24 am 
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fourtenposi wrote:
Do you typically set the front and back up the same as far as squirter bleeds/pumps?

With the progression that mine has, I was thinking of just reducing the size of the bleed up front and leaving the rear bleed alone. My rear barrels don't start to kick in till 4000 rpms and footbraking I launch at 3000 rpms. The should hopefully give it that extra fuel that it needs as I slowly roll into the throttle to launch rpm.


The front to back spread will vary depending on the linkage and combination. i.e. progressive vs. 1:1, single 4bbl. vs. multiple carburetion, throttle geometry, etc. and the biggest thing the specifics of the combination and how the driver is utilizing the throttle. Unfortunately not a one size fits all answer.

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 Post Posted: Thu Aug 25, 2011 11:53 am 
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Thanks for your input! Thats is what I figure.

Will be testing with the smaller bleed this weekend.

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 Post Posted: Mon Jul 09, 2012 3:42 pm 
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Anyone here besides Bill do this??
I thought I would go ahead and give this a try as doing the acc pump cams took a fair amount of time..Anyone??
Also thinking you can get away with a 6/32 and may only need a .015 or even smaller hole..
Maybe Bill will chime in and tell us how it worked for him.

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 Post Posted: Mon Jul 09, 2012 4:35 pm 
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Hey Guys,

I actually gave up on it. If I made the bleed big enough to limit the fuel, it would cause a hesitation because it didn't have enough pressure to deliver enough fuel quickly, than as I went smaller to get rid of the hesitation, it wasn't bleeding enough fuel to get ride of the rich condition. For me I have found the most effective way to limit the pump shot, was to sand on the pump cams.

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 Post Posted: Mon Jul 09, 2012 5:04 pm 
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Bill are you foot braking?? Or leaving on the TB?? I am leaving on the TB and was looking for it to come up lean and clean sort of... =;

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 Post Posted: Mon Jul 09, 2012 5:28 pm 
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At the time I was playing with it yes.

But if you just want to lean it out a tad, the bleed will work.

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