i need help you guys please,,
sometimes when i take the engine up in the upper area when i let off i can see gobs of smoke,fills the car like an unheard of amount has only done this since the swap from the afb to the 650 mighty. holley mechanical pump and regulator
fuel pressure gauge was at 6 took down to 4 still persists.doesnt stumble or stall.pulled needle and seats clean no distortions,moves freely..i'm not talking little bits of smoke i'm talking,if i look back i can see it sitting,hovering,lingering,
can this be a power valve issue??
thanx
shane

http://www.chevytalk.org/threads/showflat.php?Cat=&Number=922505&page=0&view=collapsed&sb=5&o=14&fpart=1

can somebody answer the question instead of giving me a link to a carb vs. carb??
it doesnt solve my issue and am in dyer need of assistance has anybody heard of,or had such a problem?
holley or demon????
thanx
shane

The link was meant to inform...it has a BG tech listed that is willing to help, along with some common problems and fixes. Just trying to help

Could you explain the problem? What is "upper area"? some place around your town? the mountains? maybe high rpm? Where is the smoke? In the passanger area of the car? under the hood? out the exhaust pipes? And you're grumpy at the one guy that offered you help???

What color is the smoke? Did you swap manifolds along with the carbs? The only thing the carb might cause is black smoke if it's too rich at WOT. Is the carb setup to factory spec's or has it been worked on?

upper rpms 3500 on up.smoke emits from exhaust,wich stops before the rear and fills the inside of the car and outside the car.it is black smoke,it doesnt happen all the time,didnt change intakes have an rpm.also it only happens when i let off the throttle quickly..no i'm not grumpy i skimmed throught the thread and found nothing of real importance to the help i actually need,if you read the thread (unless i missed something along the way)nothing really answers my. questions,i am frustrated hence the missplaced attitude wich in no way was meant to offend anybody i just want answers and didnt find any there,and i know there is a lot of knowledge on this board,and somebody has to have had the same problems(or known of)as myself.
this is the only board that satisfies my hunger for knowledge of my 71 when i'm having problems or need advice on upgrading or changing something.
so for now jim please except this as a formal apology did not mean to missplace my frustration towards you, a different wording would have gone farther.
frustrated,
shane

Possible rear float level too high, spills into the carb from the vent tube at neg. G force. (from slowing down) To help diagnose spill over, run a rubber hose from vent to vent, cut a notch in the top center of the hose. Just a suggestion.

I would second the thought that it could be the secondary bowls spilling over, especially if it happens when you suddenly let up. It is diffenitly something in your secondarys, float to high would be the most logical thing to check, also look for any signs of internal leaking. Did you park the car, take it up over 3500 rpm and see if it does it then? My bet is it doesn't, Check your rear float level and let us know what happens. Good Luck, JEFF

float level is set just below the middle line of the sight glass.when i got the carb i was unfamiliar with the design and tightened the rear needle and seat to tight and ripped the gasket,so it leaked so i bought a holley needle and seat kit,could i have the wrong needle and seat??like i said it doesnt do it all the time.i will try the hose on the vent tubes tommorrow night.
thanx
shane

Not being a smart-ass but it would be worth your time to call the tech dept. at Barry Grant, very helpful bunch.

Just a shot in the dark but is the manifold for a spread bore? Maybe with the square bore carb something isn't covered by gasket material on the base plate of the carb...

ok have troubleshooted it to be the primary side
would a power valve being the wrong size create a rich condition??
what would u guys recommend
350 .060
280h
10:2
hooked vacuum gauge to it,it reads about 15 inches ,does that sound 'bout right???
what power valve would you guys use?
i put a 7.5 in it.
thanx
shane

sometimes when i take the engine up in the upper area when i let off i can see gobs of smoke,fills the car like an unheard of amount has only done this since the swap from the afb to the 650 mighty. holley mechanical pump and regulator

I'd recommend you put the AFB back on and see how it runs.

even with the smoking still outperforms that crappy edelbrock 600 all around..........
sorry.
shane

Check that the gasket is correct for the power valve. I don't remember which gasket goes with which power valve right off hand, but, some PVs have square holes and others have round holes. they take different gaskets. Also the PV number should be about 2 numbers less than vacuum at idle. That's about all I can think of at the moment.

barry grant told me to divide the highest vacuum in half and thats the one to use???so if my vacuum is 15 inches at idle that means use about a 12 or 13 pv?does that sound right????
thanx
shane

no, i believe your supposed to take a vacum reading @ idle and divide it in half....5" of vacum would be a 2.5 p/v

The following things can cause a rich condition like you're having.

-Float Level too high
-PV rating too close to your vacuum
-Butterflies out of position
-Not enough intial timing in the engine

If you'll contact our technical support staff at (706) 864-8544 we should be able to walk you through this.

As above: those guys are on top of things and more than willing to help you out. First class operation they have.

well i wish i remembered his name but the two times i did call your tech support,member was very smug sounded young maybe a little cocky at heart.........-float level is just below the middle line on sight glass
-vacuum is 9" at idle (750-800)using a 4.5pv
-butterfly are set as described on your video
(speaking of transition slots)
-19 degrees initial
it is happening when i take the motor up then let
off the accelerator.
could it be the jets in the rear are just so big that its puddleing in the intake when i let off the gas????
shane