CARB Trouble

[HALFBREED]

OK ...
I have 515ci chevy motor .. no mater what we try with the carb it wont idle and and always run rich.. tryed air bleeds , tryed differnt metering blocks, tryed jetting .... u can see fuel dripping out the boosters ... ( cuz of low air speed in the motor i beleve) the carb is nos carb 1050 billit boosters, blocks yadayada..
heres the specs

515 ci

4.530 x 4.00
15.5-1 comp
cam 288/318@ 50 830/798,112
360 heads ( flow 440)
super victor intake
1050 carb..
Trans- PG with 3800 conv

can anyone throw some ides out there .. It would be a great help.. i have 2 weeks to get car running good for 1st race

thanks a ton Scottyk

[AutoRoc]

There should be no dripping. Check the float levels and make sure they're at the bottom of the sight glass.

[9secvega]

take the carb off and open the secondaries a bit. your primarys are open too far

[HALFBREED]

I have tryed both. ideas. plus i adjusted A/F screws no response...

adjustments on throttle plates both have tobe almost all the way adjusted to run... then you can see fuel running out the boosters..

floats are perfect...


the motor has no low air speed.......

this is what i was going to try..... see if this makes sense

idle air bleed was 43 now 53
idle circut in metering block drilled to .0625
transfer slot air bleed 70 now 80

i would hope this change would atleast pick up a signal????

thanks for the input so far

[9secvega]

im no carb expert but maybe drill a 1/8 hole in the primarys more air flow
anyone else?

[BBCStang]

drill some holes like 9secvega said

[xracer73]

Fuel Leakage:
Lower Float
Decrease Fuel Pressure
Clean or replace Needle and Seat
Inspect float to ensure it is moving freely

Running rich at Idle:
Increase initial timing
Turn mixture Screws in
Readjust butterfly positions
lower floats
Decrease fuel pressure

Big cams and low idle vacuum can make for an off-idle stumble that's often tough to cure. The problem stems from cranking the primary throttle blades open too far, which uncovers too much of the idle-transfer slot (arrow). When you lightly step on the throttle, the engine stumbles or sneezes because there's no additional fuel available to help accelerate the car, since the transition slot is already in use. The trick is to close the primary throttle blades down to where the transition slot is barely uncovered.
This step will create a too-low idle speed. One way to help that is to crack open the secondary idle stop (located on the bottom of most Holleys on the passenger side) a half-turn or so. If that doesn't help, you might try adding a PCV valve to the carb, which is also a calibrated air leak that will add a little speed. If all those tricks still don't help, you will have to resort to drilling a small hole in each primary throttle blade on the leading edge. Start with a 1/8-inch hole in each primary throttle blade and work up one size at a time. It's a slow process, but that's the best cure for the big-cam off-idle stumble.

[HALFBREED]

thanks for the info... so far guys

the big problem im having is Idle... its fine on the break and full throttle ... alittle rich through out ..... it would be nice to to get it to idle insted of 2 footn it hahahaha...

last yr same carb on our 548ci i never had to touch the thing...?? crazy

every once in awile my mustang rejects the bbc .... hahaha


thanks again for the help...guys

[AutoRoc]

More things I can suggest based on experience only..

Drop the front jets down 8 sizes and install a 3.5 powervalve. Makes my car idle and drive SMOOTH compared to square jetting.

CLEAN OUT THE AIR BLEEDS...Mine got plugged last year from rubber dust and it hydrolocked ALL CYLINDERS...not cool. It was suggested to me and wow am I lucky nothing got hurt.