89formula#1

Hey guys I am trying to get a 670 street avenger carb tuned rigth for my buddy but the back float won't do wut i tell it lol. The front one I adjust till the fuel level was in the middle of the sight glass. Now on the back float I have put the float all the way down and all the way to the top causing the car to stall and the level is nowhere to be found in the sigth glass. Theres definatly fuel in there cause its shooting out the adjusting nut on th top when i lossin it like normal. Now this carb is brand new out of the box so i can;t see the float being out of adjustment. Also I started messing withit cause it backfires threw the carb if it hit the gas. Now wunt can this be?? also No matter how i rev it the secondarie blades are not moving. shouldn;t these open? I put the lighted spring in and still nothing. By the way its on a open carbspacer atop an airgap intake. thanks for any input guys i really appriciate it..

Pony Killer

as far as the back sight plug.. not being able to see the gas.. if you can't see the gas.. you've gotta find out where it is.... if it's stuck high it'll flood and that isn't nice..

first thing.. tap the back bowl a couple times... maybe the carb got turned upside down and got stuck either in shipping or in the store.. so tap it a few times maybe it's stuck.

if it's not and you have no idea wehre the fuel level is.. take the carb off pull off the back float and set it to specs and replace it with something you can iether see through. or a regular bowl plug.

The backfiring through the carb can be because of the gas.. but it's generally a timing issue.. as in too little timing, or no advance... check the distributor.. and make sure it's working right

89formula#1

Well it already has the clear sight glasses on it. I tend to think its filled up past the sight glass for some reason. I would unscrew the nut to make the level drop correct?? Also with the secondaries when i just rev it in neutral they should open correct??? I can;t see any reason why they arn;t working. They have the lightest spring in them and they get vacume frm the carb. I guess I'll check and see if the diaphram is busted..

F-BIRD'88

The secondaries will not open by winging the throttle in neutral. Forget it. You will not see them open by doing this. They open by airflow through the primary bores, not manifold vacuum. As long as the diaphram is good an the cork gasket is betweeen the vacuum housing and carb body the secondaries will open at WOT UNDER LOAD.
There may be dirt stuck in the secondary needle and seat assembly causing it to be hard to adjust the fuel level. Clean it.
Set the float up like this to start. The final adjustment will be real close to this.
You have to open the secondary throttles a little by hand while setting the float level in order to use some of the fuel in the bowl and get an accurate fuel level.

89formula#1

Ok guys I figured it out with your help and got it fixed, I looked in the back sightglass and i could see the level if i shoot the car while it was runnin and it was a little higher then the glass so i adjusted the float a tad lower while it wasn;t runing so i didn;t get sprayed with fuel then i started it back up and it was rigth were i wunted it. even after a drive it was perfect. So the floats are both adjusted right and it was still backfiring so i turned to the timing and hooke dht ligth up, turns out it was only moving liek an inch off the mark at liek 4 grand so i put some lighter springs in the dist. for the mechanical advance and hooked up the vacume advance and now its great, runs awsome no pop alot more power. I still have the mixture screws 1 1/2 turns out caue i wasn;t at my house so all my tools weren;t there so i didn;t have my tach and stuff. but its still only got about 300 miles on the engine so it doesn;t need to be perfect yet. I just wunna thank you for you help I am alot happier now lol. Oh and one more thing, Its a ou of the box 670 avenger on top of a 327 with aroudn 9.5:1, airgap intake, dart iron eagle 2.02 180cc heads and a XE274 cam with complete msd ignition. Now I think its runing a little lean rigth now cause u can;t smell it at all. Do you think it is or should the jets be fine for wut it is?? If not what do you suggest. I am new to Holleys so any input it great. thanks again

F-BIRD'88

When the car is right you won't be able to"smell it at all"

How it smells at idle has nothing to do with the carbs jetting.

The jets come into effect when you're driving down the road at a fairly good speed.
Anything under that is the idle circuit.
Stock jets will be fine for now.

89formula#1

I was gonna have him buy a jet kit tomorrow, should i have him hold off or just get it cause i will need it to make it run the best right

mw66nova

iTrader: (13)

it's always a good idea to have a bunch of different jets when tuning a holley.

89formula#1

Oh yea guys one more question. I know when I take the front bowl off to change the jets fuel will come out. So is there a way to drain this or what?? Run the car with out the pump on?? lol j/k

1FastZ

Get yourself a spray can lid and take out the bottom bolt. the fuel will fill nicely into the lid. Don't worry it will not fill the lid.

F-BIRD'88

You don't need the whole jet kit.

the jetting will be within 4 jet sizes up or down from what comes with the carb.
On that motor the supplied jetting should be real close.
If its severly lean or rich I'd look for a vacuum leak'or an ignition problem first.
Getting the ignition advance curve dialed in for the
the cam he has will go much further than changing jets.
do the ignition first.
The MSD distributor is fully adjustable.

89formula#1

ok guys we have eveything dialed in and it runs great when just crusin but when u stomp on it nuthin, the secondaries arn;t opening I think. I tried the strongest and the weakest spring ans nuthing at all. timing is set at 12, the vacum advance is hooked up to ported and mechanical advance has the smaller silver springs on it. I don;t get why the secondaries won;t open though, its a brand new carb...

F-BIRD'88

You mentioned in an earlier post that the mechanical advance was barely advancing. You want it to advance to 32-36degrees at high rpm.