FakeSnake

So i got tired of screwing around with fuel injection and decided to go blow through. rebuilt a holley 650 double pumper and slapped it on the victor jr. and every time i try to rev it it wants to backfire through the carb. i thought it may have been getting too much of a accelerator pump shot so i moved the cam around one hole to lessen the initial squirt but that didnt seem to help. i am lost and looking for advice on where to start looking for the problem. it has 66 main and 67 secondary jets, a 6.5" powervalve and a powervalve plug in the rear. what am i missing on why the carb is doing this?

i also just realized that when i was snapping the throttle open that it was falling on its face like it wasnt getting enough fuel from the accel. pump until the main metering system kicked in and started delivering fuel...


http://s155.photobucket.com/albums/s...=VIDEO0010.mp4

speedtigger

iTrader: (16)

Popping through the carb is cause by a lean condition or too little ignition timing advance and sometimes by fouled spark plugs.

FakeSnake

ill check the plugs tomorrow, i have the timing set a 20* btdc from 0-1500 steps down to 18 from 1500-3000 and 15* 3000-redline this is approximate since i dont have the timing map in front of me.

should i add more main jet? i really dont think its lean...

S10xGN

iTrader: (11)

For a plugged PV, jets should be 6 or so sizes larger. I have 71/80 jets, a 50cc primary pump, brown cam, hollow screw, and 0.035" squirter on my 750DP. That timing curve looks real light. You should be using a MAP to pull timing under boost, not running with low timing.

FakeSnake

what is the hollow screw youre talking about? and the timing is just to get a baseline and get things running well enough to where i can drive it and tune with a wideband. i do have a 6.5" powervalve in the main metering block. maybe ill try a plug and step up the jets tomorrow.

S10xGN

iTrader: (11)

Your 1st post said the secondary side had a PV plug, therefore the secondary side jets should be increased 6 sizes minimum. The hollow screw is for the squirter nozzle so it won't get starved out. Throw some more timing on it and see what happens, most guys here are running between 30° - 36°...

FakeSnake

ok thanks, ill check everything out tomorrow and report back with my results

StrokerTA

Needs a larger primary squirter first off.. Timing curve is goofy too