holley/demon carb gas mileage tricks

[party340]

I found this article on carb tuning:

http://www.chevyhiperformance.com/te...age/index.html

I dont have a a/f meter and I have an 800 holley double pumper that does not have screw in air bleeds. So I decided to set up my carb with the same specs as the modifed demon 750 in the article. I did that by using the tip of a lead pencil .5mm, some jb weld, dremal tool with dremal bits. The .5mm lead pencil tip has a 0.020 oriface, the same as the idle feed restrictor in the article. So I cut the pencil tip off using a dremal cut off wheel and I got a copper wire strand and inserted into the pencil tip and put a drop of jb weld on the side of the pencil tip. Next i inserted this into the idle feed restrictor. The purpose of the coppe wire was to keep the jb weld out of the oriface and to align the pencil tip with the old oriface. I then let it dry and cut the prodruding pencil tip down with a dremal drill bit. Next I used jb weld epoxy putty over the idle air bleeds and used the smallest dremal bit to drill the 0.03 hole. Then I used another dremal bit to do the 0.093 hole for the high speed air bleeds. To be honest I gave the carb a 50/50 chance of even running have a$$ed. But the motor fired right up and the smell of unburned fuel from the exaust disappeard. I then drove the car and the carb did not hiccup once! Laid into it and it seems to run just as hard as before. Heres the good part. Ive been driving the car all week and my fuel milage went from averaging 13mpg to 18 mpg! I have not been to the race track to verify performance, but the butt dyno says the car pulls just as hard as before.

Heres my combo

A 340 with kb pistons, 242 @50 ultradyne solid with .548 lift, 1 5/8 headers into 3 inch flowmasters with rpm air gap, 3.91 gears and a tremic 5 speed in a 67 dart. The engine in the article pulled around the same vacuume as my engine so i said what do I have to loose?

[rumblefish360]

Well, your combo is not a mileage getter, but getting the most from your combo is a good idea. IF you can spend the cash for a A/F meter, you'll be ahead of the game. That is an excellent tool.

A carb with adjustable/changeable air bleeds is a spendy carb to switch to and dialing in the carb is a time consuming pain. Now before you say, I can do it, which I have no doubts that you could, but carbs fall in and out of tune near daily nevermind next months weather changes.

[crisser]

Yeah. Most or all the Holley performance carbs. are set up on the richer side because they don`t know, at the factory, which engine it will end up on. The idle circut is one that is set up rich also. So, most box carbs can be tuned on to get max results out of YOUR engine. Like I heard a Dyno operator say, "you can be rich forever but only lean once".