600 cfm holley problems

Perhaps you have the floats adjusted too high or there is dirt/foreign material on the needle and seat. Holleys are more susceptible to foreign material than factory carbs are and require a good fuel filter.

I would also check to make sure that the metering block gaskets are correct and installed in the right direction.

A bad power valve (or gasket) can cause an over rich condition too. I doubt if the valve found in the kit is too mis-rated for your application. Did you have any back fires while starting up the car with the new carb installed? What value power valve do have?

Biggest thing in rebuilding a Holley is making sure you've completely cleaned out all the tiny passages in the metering block. I soak the parts in carb cleaner for a couple days, then blow out these holes with spray carb cleaner (wear eye protection doing this) then blow out the holes with compressed air. All it takes is one blocked passage to gum up the works. You should have a 6.5 powervalve in there. And like Dennis stated, make sure the metering block gasket is correct and not blocking any holes in either the main body and metering block.

I second the flooding diagnosis...
Float too high is best bet.

Holleys are a super carb. You have a good thing going with the stock intake and 1850.
The only problem is that you are going to get frustrated at some point and become a Holley basher unless you do something fast to understand what you are working on.
I highly recommend you buy some books and read up thoroughly on how to tune Holleys. If not, you will spend all of your time here asking questions about every little thing, rather than enjoying a great car with a great carb.
Dave

ratio411 said:

I highly recommend you buy some books and read up thoroughly on how to tune Holleys. If not, you will spend all of your time here asking questions about every little thing, rather than enjoying a great car with a great carb.
Dave

Click to expand...

That is some great advice and I, of course, agree. Purchase the Holley Carb Tuning book & it'll save you some headaches.

You want to start w/ensuring the floats are set correctly; make sure the car is on level ground and running. Pull the sight hole plug (recmnd laying some towels under the sites in case fuel leaks out) and adjust the floats so fuel is just BELOW the site plug. If fuel is just pouring out, shut the motor off before you start a fire; adjust the floats (CW will lower the floats, CCW will raise the floats). Next thing is to adjust the idle... you might want to adjust the idle first since it won't idle on it's own, adjust the floats then go back and adjust the idle again.

Have you pulled the plugs? I'm betting they are sooty as can be.

I agree with the guys above, it's dumping big time.

Once you get it sorted, look at re-jetting. If your motor is stock, it will run much better if you drop the jets down. I had one on Chepie, and I dropped the primaries way down and got it to run very nicely. I think I dropped from 65 to 59.