Holley question

[Ian70mustang]

I have a 70 with a 351C and a holley r-1850, if you dont know what that is its a 600cfm, vac secondary, Side hung float, 4160 (no secondary metering block), manual choke (i took it off, I'm in San Diego, not much need for it) Anyway, I'm pretty knowledgable about holley tuning and functioning, but this one has me beat. My idle was getting rough so i went to tune it with the mixture screws, but when i turned them all the way in it did nothing (and in case you're wondering this is not an emissions carb, so its not reverse idle). Before when i would tune the idle it would die if i turned them all the way in. Any idea what could be going on?
p.s. whatever i did it idles even worse now.

 

[D.Hearne]

Sounds like it's time to put a kit in it. Get a 1 gallon can of carb cleaner ( this is the kind you want to soak the parts in) a couple of cans of spray carb cleaner, a kit and rebuild it.

 

[D.Hearne]

You might even want to consider upgrading to a 3310 750 Holley, instead of rebuilding the 600.

 

[Mach1steve]

sounds like a rebuild is needed to me.
I have a used 3310 750 if you want it ?
Works fine, I just swapped it for a 650 Dbl Pumper (goin racin).

Mach1steve
www.muggziperformance.com

 

[Ian70mustang]

Rebuild? the carb was out of the box new 1 year and 4,000 miles ago. thank you for the suggestions though.

 

[10secgoal]

If nothing happens when you turn them in you are getting extra fuel from somewhere else dude. Bad power valve gasket is what had me looking for days. I knew that pv was good but it was the damn gasket. Anyway, it has to be drawing gas from somewhere or it wouldn't run. How far open are your primaries...are you just tipping in ? You could try to adjust te secondary butterflies do add more air, see if that changes anything.

 

[rbohm]

also make sure the metering block and the metering block mounting surface are flat, and that the gasket is in good condition.

 

[D.Hearne]

With a 600 on a 351C, his motor might be making enough vacuum to be opening the secondaries slightly, and this will aggrevate the idle settings also. I had this problem on a 390 and a 302, with a too light secondary spring. After swapping in a little heavier secondary spring, the idle problem went away.

 

[pabear89]

No change with mixture screws,
you have a internal leak of float level off,front or rear.

I was just setting my valves and noticed a small amount of fuel seeping from
the shaft on the rear plate,
I was checking the valves in prep for the run to Tuson, Had it out for a short run and it was not feeling right.
The rear float was just at the point where it is hitting the overflow point,
and the vac draw was pulling the fuel in.

A 750 would be
That low milage and time could be just something simple.

PB