another carb question

[maw08080]

Hi, someone please help me, I am a carb idiot and just can't figure out my problem.
I have a ZZ4 350, TrickFlow heads 2.02 1.60, A comp cam .474 .474 gross lift 107. lobe C.L. MSD 6AL plus box, MSD mag pickup dist, Blaster coil, air gap intake, and a Holley 650 D.P mechanical secondaries in a manual Chevy k1500. 4.10 gears.
I just can't seam to get this thing to stop popping out the carb on moderate to heavy acceleration. i now have the carb set very close to out of box spec. with 10 deg. advance on the dist. and heavy springs in it.
It seems like any change I make to the carb adjustments and timing adj. improve one problem but make something else worse happen. I don't believe i have any vacuum leaks for I read 15-18 in. of manifold vacuum at idle.
Any advice? I am open to any suggestions, I will try them

[thevic24]

Re: another carb question

check the power valve. also, have youtried messing with the squrters?. when it pops dose it have a flat spot?

[maw08080]

Re: another carb question

Yes, have messed with about everything, Power valve is a 65 and this carb has the blowout protection circut in it.

[maw08080]

Re: another carb question

Oh, and Yes it has a horrible flat spot, i have a O2 gauge in it and when I lightly rest my foot on the throttle (like cruising speed)it goes lean andstumbles under light acceleration from there. I have even tried different cams on the pumps, those were not the answer it made everything worse. A side note advancing the timing to the moon (30deg base vac. adv. unplugged) had unexpected good results. but is definitely not the answer, it's back to 10 deg base right now.

[thevic24]

Re: another carb question

you might need 50cc acell. pumps. is there any stumble from idle

[std]

Re: another carb question

Are you sure you have the accelerator pumps set right? I would double check to make sure it's getting a full squirt.

[maw08080]

Re: another carb question

I have bought a 50cc pump kit but, haven't installed it. I can get black smoke from just changing the cam from the stock pink. to a orange one. and that's just the primary side.

[maw08080]

Re: another carb question

I can't even count the times I have checked the setting on the pumps, no matter how i adjust them it dosn't really help. I know i am very close to getting it all right. I just can't work out this one little thing.

[thevic24]

Re: another carb question

do you tried moving the vac. advance line from ported to manifold and back?

[chad786]

Re: another carb question

Float level?

[maw08080]

Re: another carb question

Relocating the vac. adv. line i have not tried, it is on ported vac. right now. Would you mind explaining why you think this might work? I would like to know the theory behind it.

[thevic24]

Re: another carb question

another thing with holeys, check the throttle base, ive had them crack(very,very small) and cause this.

[maw08080]

Re: another carb question

I have moved the float level around and it seems to be best at about half way up a sight glass.

[thevic24]

Re: another carb question

don't have a theory but with my truck i need to use manifold vacuum. when i had it on ported, it would sometimes backfire under a heavy load. nothing worked well but when i swapped it it worked perfect. sorry i cant explane it though.

[maw08080]

Re: another carb question

I had the carb off just today to reset the butterfly's to stock location. I didn't notice a crack but i will be sure to give it a good look tomarrow. This carb is brand new, well it's a year old with only 500 miles on it. It has been like this sense day one. good thing i have a lot of new gaskets.