maxpower671

that's a great question! :idea:

cncmotorsports

Depends on the application. Street Strip AED makes a Great carb (We use them on all our crate engines and drag race engines.
They are all built different so you will get different results.

AED 850 HO 549.95 AED 850 HOM $629.95

miked24

Thanks for all the info guys some great stuff experience helps alot.....

Cnccncmotorsports how much is your shipping to Bronson Tx 75930?

cncmotorsports

buy threw our on-line store $10.95

hammertime

Mike, I took a 850 APD in on trade a few weeks ago, its fresh and ready to go now. $625.00 to your door. :wink:

bjuice

David you are 100% correct..I have got a friend that does head work at Clements racing in Spartanburg S.C. where they CNC machine virgin aluminum heads for DART...and he states they face this issue all the time with heads etc...I am sure a-lot of this is due to the loss of Power thru the chassis set up etc....

Not to get off the subject But I have seen 30hp difference in 1/2 degree of pinion angle on chassis dyno.

side NOTE: I spoke woth John today at APD and they are gonna Convert my Stock 750 cfm Holley Carb to a e-85 CARB for the 73 z-28 camaro street car I have....$595 plus shipping !

jmarksdragster

This is my first carb this large, so I can't give you a definite answer yet. I do know BLP has run a few different sizes across their 673 Sonny's engine, the 2.600 throttle bore is what they ended up with.

The issue with any big carb is providing a strong enough metering signal to maintain CONSISTENT fuel metering at the lower RPM's. Most will show more peak power and carry father past peak torque, a good clue is how peak torque is affected. If you gain there and have the gear and converter optimized chances are it will gain. There is a balance point with any engine as to having enough pressure differential at the booster to help with atomization and how low you can go to see gains from pumping losses. Every engine is different, and throw in different port and combustion chamber designs, ignition systems, engine temps and fuel used you can change a lot an in some cases not appear like much. My SB2 ran the best with a 1250 over a smaller carb, my friends pump gas 540 runs as well with a 1050 as anything bigger. The difference is in the port designs, compression, and fuel. Low compression and pump gas despite being made to work together are not the best combination for a race car. Vaporization characteristics of pump gas sucks... and low compression doesn't help. A smaller carb creates more vacuum under the carb, creates a better pressure differential, and that aids atomization and vaporization. Burn the fuel more completely you need less, and make more power.

The engine this carb is going on is for the challenge at BLP, it's a 622 Steve Schmidt engine with 11° Big Chief Heads, these are high velocity Pro Stock style heads. It should be an extremely efficient engine with a VE at least or over 110%, and hopefully my choice on size will be close. I found some interesting things on the flow bench, I'll see if they will help a little as well.

As far as injection I don't have any experience there, but I suspect much the same there with vaporization. A TB too large will have less vacuum to assist in vaporization. You might try raising fuel pressure and cutting back on jet size to compensate if that is possible. Consider how air conditioning works. Pressurized freon goes through a restriction and drops pressure. The liquid freon changes to a gas, and the temps drops. Methanol already does that to a degree, but if you can vaporize the fuel better you may not need quite so much and gain some more power. Of course other factors are involved, for one look at the ignition the Top Alcohol cars use. You need a very strong ignition to light the fuel when you start adding more. The right heat range plug, the right engine temps...

jmarksdragster

After anodizing.

ken0069

After living most of my life not knowing much about carburetors then in the past few years learning a fair amount about them and building a few myself, I've somewhat changed my opinion on carbs and carb builders.

It was my thought in my early years that carburetors were a "black art" and that only a select few ppl ever really understood them enough to be able to fine tune them but with O2 sensors now being pretty reasonably priced and many racers now installing them on their engines, they have changed the carburetor tuning landscape forever.

Having said all that, the incident you referenced with the Braswell and QuikFuel carbs is a classic example of what I'm talking about. It's my opinion that NO carburetor is going to be dead on out of the box! It's also my opinion that ANYONE that wants the most out of their carb, whether it's custom built by a Pro or one that you hobble together on your own, unless you understand the fundamentals of tuning one and fool with them yourself then you're likely never going to get the most out of it because EVERY engine/car is going to be different and the builder (unless it's you) can't be there to fine tune it for you. :wink: