Which Eddy for me?

-
If money were no object one would maybe buy both and test to determine which would be ideal for their setup, or do as much research and calculating as possible and make a single choice. But one has to be prepared to spend more time than many are willing to spend in order to get either spot on. Most know there are no such things as bolt-on carburetors. Gotta tune. That's what I'm doing now with a 750 Street Demon. Had some at the dragstrip, after some runs mention they'd go bigger. Well, I'm tuning the thing till I can't tune no more. Then I'll see. For street it's good, strip, yeah, a little bigger might yield more power but I know that since that trip to the strip and the tuning I've done afterwards it's a whole lot better now. Another trip will tell the tale. My take? Buy the 650, enjoy the crisp throttle response it will likely provide, or go for the bigger one and theoretically get the extra power. But tune either to maximize. I subscribe to the advice in the old S-A Design book Mopar Performance by Larry Schreib which says go slightly smaller vs bigger.

IMG_20180421_165925.jpg


IMG_20180421_165944.jpg
 
demon322 said:
Say I went with the 650. How would I know if its not enough?
Click to expand...

I read one article (I think it was an online Hot Rod article) where they were going with larger and larger carbs til they found the optimum. iirc.... they were doing test runs on a dyno. They watched manifold vacuum at WOT. They would do a pull and watch the manifold vacuum to see if the carb was flowing enough, i.e. if there was still significant vacuum at WOT, they tried the next biggest carb. If I understood correctly, they were looking to find the carb with the right amount of flow to give the motor all it wanted to pull in. In lieu of a dyno, I guess you could mount a vacuum gauge in the car and have some watch to see what it drops to at WOT.

Is it worth it for a street car that doesn't see WOT often? Probably not.

I did a quick search and found the article. It was a Car Craft article,... about Barry Grant's thought on finding the right size carb.

Selecting Right Carbs: How Big Is Too Big?- Car Craft Magazine
 
Last edited:
Thanks for all the input and advice. Lots of good info here. Those articles are very interesting.

I think I have decided to go 650. Throttle response and good manners on the low end are a plus. I realize I may lose some on the top end but I’m hoping I won’t notice too much on the street, and the days at the track aren’t all that frequent.

Also the fact that I wanted to try the AVS 2 and the 800 isn’t available yet but the 650 is. I’ll give it a go. If I hate it a gently used carb may be for sale in a few months lol.

Thanks all.
 
You must log in or register to reply here.
-

Back
Top