Thread: Question about my holley carb..Bogs when I hit the gas..

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I have to take my vacume guage home from work tonight. It just dawned on me that I have the vacume advance hooked up to the port on the side of the metering block. I know it has advance, but I forgot that the holley has a port just above the throtle plate as well. I never checked which port to use with a vacume guage.. Maybe that is my problem.(No I an not talking about manifod vacume either.) It has been about 10 years since I played with a holley, so maybe it is as simple as that I have the advanced hooked to the wrong port.

Well, after work tonight I took my vacume guage to the engine.. In drive, while foot is on the brake, I have 14inch of vacume.. I know I put a 6.5 power valve in the carb.. I first unplugged the vacume advance from the port where I had it on the metering block on the holley and checked the vacume.With the guage hooked up, and a quick snap of the throtle the vacume dropped, then went up..The same thing happened on the port below that on the throtle plate..Hummm So which port is it suppose to be connected to? I am not refering to the large manifold vacume port in the rear, I know better than that, but I can't remember which front port to use, the one at the block or the throtle plate.. Tech Inspector, you are good at this kind of stuff, what do you think..

Connect the vacumn to the metering block and take the main jets down to 64's

Why 64? I am not sure what it came with stock, guess I will have to pull it apart. How did you come to this conclusion?? Just trying to learn.

a mild 350 for street cruzin only needs about 450 cfm. a 600 holley will work fine if leaned out 2 steps down from out of the box. i change to the 50cc acc pump and use 62 to 64 primaries.
personaly for my sbc i like the 390 holley.

What shine said. A 750 is way too much carb for a mild 350 on the street. A 650 is bordering on too big and I ran a 650 DP on a fairly milld 400 and had to jet it down to 64's so it wouldn't run so rich.

Originally Posted by jchrisd

Why 64? I am not sure what it came with stock, guess I will have to pull it apart. How did you come to this conclusion?? Just trying to learn.

3310 750cfm should have come with 72's up front and a 6.5 PV.

I run a holley 750 DP on my mild 350 and have no hesitation. Its all in the tunning. MY bud runs a proform body and front metering block reworked body to ~850cfm on his ford NA 302, radical cam and head setup and runs mid 11's all day long and as crisp as you can get. If you have some one local who can tune it for you Id stick with it. Bud thats just me.

Okay, after thinking about this, do you think it might make the most sense to remove the over sized carb, and go with either a holley 600 electric choke, or a Q-jet new (from say a 75-75 model car with electric choke?? The original carb was an electronic q-jet, but I removed all the computer stuff, ect..I guess I could always sell the holley on ebay, as it does work, just a little too much so for my engine. If I installed the 64 jets, would that solve my problem? What about the shooter size?? I called Holley and they told me I need a BIGGER shooter.. I dunno about that. I sometimes hate calling the tech lines.. I called Comp cams 4 different times, and got 3 different suggestions for the same aplication..I sometimes wonder who is on the other end..