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383 SBC LT1 late model type gen2

vic intake [email protected] cam on a 106 .640 lift
heads are 280's @ .600
super sucker
13:1 static

And I have a 750 H.P. carb Is it too small?

car runs 98 in the 1/8, 125 in the 1/4 1.50 60'
 

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More than likely the 750 is plenty, but the 950 would be a better choice. It only flows a tad more than the 750. The difference between the 2 is probably no more than .03-.04 over the 1320.
 

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I'm going out this weekend to see. I just bought a handheld vacuum gage that I will connect to the vacuum port that was just installed at the base of the carb.

I am going to run it into the car and try to look at it going 165 mph. I have an 1150, but some feel it is too small.
 

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If you pull any vacuum at WOT, the carb is too small.

Not true!

Most bracket cars will need to run between .8" to 1.1" hg at WOT. Head up Class cars will be .4" to .6" hg at WOT.
A Pro Style car (Pro-Stock, Comp, Pro-Mod) will be .1" to .2" hg at WOT.

If there was no vacuum at all there would not be enough air velocity to draw fuel through the carburetor.
 

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Not true!

Most bracket cars will need to run between .8" to 1.1" hg at WOT. Head up Class cars will be .4" to .6" hg at WOT.
A Pro Style car (Pro-Stock, Comp, Pro-Mod) will be .1" to .2" hg at WOT.

If there was no vacuum at all there would not be enough air velocity to draw fuel through the carburetor.
From my experience, every time I increased carb cfm the car went quicker. I am going from what I have been taught to what worked. You, I am sure know alot more than I do.
 

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So a motor pulling 3 or 4 inches of vacum needs more carb?
 

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Who makes a handheld vacuum gage with a range of say 0 - 10 in, but the gage is big and easy to read. I just bought a Sun gage but the increments are very small and would be hard to read at the big end.
 

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Hey I have another question tied to my first.

When we dyno'd the hat read more cfm then the carb is rated for. How does that work and what does it mean?
 

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Hey I have another question tied to my first.

When we dyno'd the hat read more cfm then the carb is rated for. How does that work and what does it mean?
It doesn't Mean anything other than that is how much CFM your engine is flowing. The actual air flow is determined by the engine, not the carburetor. Carburetor flow numbers for those that use them are just a baseline number from a flow bench.

When they had your engine on the dyno how much vacuum did it produce at WOT?
 

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It doesn't Mean anything other than that is how much CFM your engine is flowing. The actual air flow is determined by the engine, not the carburetor. Carburetor flow numbers for those that use them are just a baseline number from a flow bench.

When they had your engine on the dyno how much vacuum did it produce at WOT?
3 or 4 I think.
 

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3 or 4 I think.

If the engine was pulling that much vacuum at WOT, I would check to see if the carburetor was actually opening all the way. That would be a ton of vacuum, and most engine shops would never let a race engine leave with that much vacuum. A good high performance street engine is only going to be in the 1.5" to 2.0" range.
 

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From my experience, every time I increased carb cfm the car went quicker. I am going from what I have been taught to what worked. You, I am sure know alot more than I do.
I was running a 1050 DOM on my 468. I swapped it back to a 850 which was modified and it ran faster and was more consistant so bigger isn't always better. Same line of thinking I have a reworked 1050 DOM on my 565. When it was on the dyno we tired a 1150 and my friends 1250 Pro Systems carbs on it. I lost a little power at low RPMs with the 1150 and the 1250 but gained like 2 HP and a couple numbers of torque with the Pro Sys 1250 at high RPMs. Bigger just isn't always better in my experiences. A reasonable size carb with good booster signals and good BSFC numbers always makes my junk run good. I pay my carb guy to figure all that out.......LOL. RM
 
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