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Can anyone tell me what setup they use in their Holley 700DP (4150)carb? I am having a lot of trouble getting this carb to work on my car and I could use any help I can get. I have a 351C with 4V quench heads, Blue thunder manifold, Lunati cam #00093LK, 11.0:1 compression, and a steady 6.5psi of fuel pressure. This carb runs extremely rich (~13.3:1)during steady low load cruising even though I jetted down from the original 69 primary jet to a 64 and it made little difference. Also I have a huge lean hole when I wing the throttle open at low to mid RPM’s. This lean hole is worse if I only go half way to the floor (staying on the primarys), but is still very bad when I go all the way down as well. For this issue, I have gone all the way up to # 40 squirters (original was 28 pri and 31 secondary) with the large pink pump cams and it still goes off the A/F meter scale lean for .5 seconds and then takes off at anything under 4K rpms. Two things to note here are, first I have a Holley 600DP which has no drivability issues at all (put it back on car as a test and it still runs great, just less overall power then the 700DP). Second note is that this is my second new 700DP and it has the same issues as the first. What am I doing wrong here? Is there some air bleed changes that need to be made? Is this carb just way to big for my application?
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Thanks a lot for the replies! I have tried lowering the float level before on different occasions. One time down to ¼” below the opening and it had no positive effect on the rich condition. My idle vacuum is around 13in (using the vacuum advance helped idle quality a lot). At no load cruise it runs about 15in. My power valve is a 6.5in. I also tried one from another carb just to verify the PV wasn’t blown.
There are only a few ways for fuel to get from the carburetor into the intake manifold. Through one of the metering curcuits, or the power valve.

If changing primary jets didn't make an improvement, if the fuel bowl level is set properly, if the idle metering screw is in the ball park, if a known good power valve is installed, then what does that leave us?

Could it be that your intake manifold vacuum is so low at cruise conditions that the power valve is opening? Have you checked intake vacuum while cruising around in the car? (easy to do with a long piece of vacuum hose & a gage)

cowboy from hell
Power valve should be 1/2 the manifold vacumn.

Accelerator pump lever at idle should have .015 clearance.

Pump nozzles ... trying jumping up 3 sizes and see if you have a difference.

Remove the small filters in the fuel inlets and put one inline filter.

Put on a fuel guage and check to see you are getting pressure all the way thru the acceleration curve.

Jetting ..start off at what was recommended for a stock 351C and jump up 4 sizes at a time.

Check the plugs that they are not too hot.

Timing make sure your at 30 full advance 5000 rpm

Thanks Ron and George for your replies! I have looked at most of these things before.

My PV is a 6.5 with an idle vac of about 13 and cruise vac of about 15inchs.

I setup the pump lever when I tried a larger pump cam.

For the lean bog issue I went up from a 28 to a 40 and there is still a hole.

This carb didn’t come with those small filters.

Fuel pressure stability, plugs, and timing work very well with my 600 cfm carb so that shouldn’t be an issue…right?

Approximately what should be normal jet sizes and pump nozzle sizes for this engine with a 700DP carb?
Personally I would drop to a 6.0 PV.

I have never changed a pump cam ..I would go back to the original one.

A " LEAN BOG ISSUE " Lean is a popping sound and BOG is too much gas .. RICH. What do the plugs look like?

Fuel pressure is OK but plugs would make a difference I run AF or BF-32's ...

Jet sizes ? Honestly I'm at work I will check ...I;m sure someone else may be able to chime in ... the baseline that came with the carb that I purchased was very lean also.... and mine is a HOLLEY AVENGER 700 vac secondaries.

> Best reference for setup I've seen.

Wow, has it really been 4 years since I put those notes together?
Those were supposed to just be the quickie notes until I put my
more detailed notes together in a form someone else could follow.
I never really got around to doing that. Maybe a project for the
coming winter. Since I wrote that, I've purchased a wideband O2
sensor which really helps in tuning a carb and pays off in the
long term reliability, performance and economy of your engine.

Dan Jones
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