Fuel curve, 850 mighty demon

Posted By: Verga

Fuel curve, 850 mighty demon - 01/19/09 12:01 AM

Has anybody run a 850 Mighty Demon on a BB and if so is the fuel curve close at all for a BB?

Just wondering if they are close OOTB or not.

Posted By: 602heavy

Re: Fuel curve, 850 mighty demon - 01/19/09 12:46 AM

Those mightys are wayyyyy rich on idle , had to mess with IABs/IFRs , also moved IFRs from top to bottom of well , helped with the idle issue.

These BG carbs are duration specific , every one i've had i had to dismantle & clean , get a free pile of swarf with em too.

I would still use em though , pretty good carb once set up.

Posted By: Dodgem

Re: Fuel curve, 850 mighty demon - 01/19/09 12:53 AM

Generally a carb from the manufacturer will be jetted pretty close for any V8 as the air flowing through the carb affects things in the venturies and air bleeds to give a pre determained air fuel mixture at X amount of air flow. Usually only only changes are needed for compression and of course elevation.

Posted By: dave571

Re: Fuel curve, 850 mighty demon - 01/19/09 04:16 AM

Quote:

Has anybody run a 850 Mighty Demon on a BB and if so is the fuel curve close at all for a BB?

Just wondering if they are close OOTB or not.

It may be, but you need to be more specific.

What big block?
What cam?
What car?

I ask what BB because I used to run a well set up 750 mighty demon on my 440. IT worked really well.

Well enough, that I've sen no improvement with a 950 hp holley.

That said, if the BB in question is a 400 or 383, you don't want an 850 mighty. Even on a 440 that see's street time, I think it's too much

Even if it is close to what you need setup wise, I agree with the remarks made that you need to go through it before you run it. I love BG carbs, but they need to put them together a little better.

Posted By: Exit1965

Re: Fuel curve, 850 mighty demon - 01/19/09 01:09 PM

Quote:

Even if it is close to what you need setup wise, I agree with the remarks made that you need to go through it before you run it. I love BG carbs, but they need to put them together a little better.

Or a lot better. My 825 CFM annular discharge carb which is supposed to come with 80/88 jets came with 80/65 jets. No kidding. Luckily I didn't run it many times on the 2ndaries when it was like that or some serious damage could have been done.

I had taken it apart when I first got it to check for metal shavings, and did not find any but did find flashing from drilled holes, and some incompletely drilled holes. It didn't occur to me at the time to check the jets.

When I contacted tech@bg about the jets, a guy who posts on the Hotrodders site, he was nice enough to send me replacement jets (all around) and new gaskets.

Once I replaced the jets though, it is a carb I like quite a bit and was fairly easy to make idle correctly with a lumpy cam and lower compression whereas other (albeit lower performance) carbs wouldn't idle. I haven't been inclined to run any fuel curve tests on it, but it seems to work fine for me.