Recently bought a used Holley #1850 600cfm carb. I soaked it for two days in carb cleaner, sprayed more carb cleaner and compressed air through all the openings and put a kit in it. I've rebuilt dozens of carbs with good results, but this one is giving me fits. Everything is adjusted per the kit's specs, bolted it on, ran 5 minutes and started flooding out the bowl vent tubes. Pulled the front bowl off, checked the needle and seat, they looked fine, so I blew air through them and put it back together. Same thing. Tore it back down, checked the floats and adjusted them a bit lower, same problem. Put in another needle and seat, tried it again. Ran fine for a few minutes and then started dripping fuel like it had a bad power valve. All these parts were new, but I changed the power valve and it is better, but sometimes starts surging when driving or tries to die at an idle. It's intermittent. Sometimes it runs great. I have a new mechanical fuel pump, but it worked great with the 3310 I had on it, so I can't imagine that being the problem. Holleys are pretty basic, or so I thought. Have I missed something or should I chuck this POS in the closest lake?

the pump psi was acceptable on the other one so it'd have to be OK on this one. either the float or a part of its linkage is hanging up in its travel range or one of the mini screws that bolt it in is loose (you woulda caught that by now) or the float is partly saturated or Murphys law several bad needle/seat assys in a row. As you know its just like the float assy in a toilet tank, pretty basic. EDIT another possibility is minute debris in the fuel holding the needle open on occaision

The float may have a pinhole in it and fuel is getting inside the float. I have had that happen to me. Also had a nicked "O"-ring seal on a needle/seat assembly allowing fuel a path past the needle/seat into the bowl

X2 on the O ring, Forgot about it, it needs to be lubed so it slides down without risking it tearing

The Holley 1850 uses side hung floats not center hung,no o ring.

might want to rethink the fuel pressure at the needle.

my duel feed 3310 will handle a little more psi than my single feed side hung float/bowl 1850-3 won't.



I had some issues kinda like that with my last 1850-3 600 cfm holley. had 8 psi and would over power the needle/seat, cut back to 5 psi and its all good. the 3310 and 6213 800cfm spredbore worked fine with the 8 psi

I converted it from a 4160 to a 4150 replacing meter plate with a meter block then added a QF adjustable vac pod to dail in the sndarys

fixed that little carb up and works great on a 318.

I used a regulator to cut psi down from 8 to 5 psi with my mech pump.

Well, I guess my next question is, what regulator do you recommend? I've been looking at one from TrickFlow, 4.5-9 psi. Has 2 outlets and is rebuildable should the need arise. With dual outlets, could I install a pressure gauge in the second outlet and get a correct pressure reading?

I used an electric pump/regulator kit from MrGasket.

I feed it from the fuel cell with a -8 (1/2" line) in/out of my filter/pump up to the reg. then fitting in the reg for gauges both sides

I used a -6 from reg/gauge to carb on 1 port

I used a -6 from reg/gauge back to cell with a restrictor (#2 Philips hex bit) in the 90* fitting at the gauge. I got 5 psi on carb line with 3 psi on the return line.

by circulating the fuel I am able to keep it cool running thru a cool can,the pump does not deadhead against a regulator, and does not run at freeflow with some restriction in the line.

you could use 1 or 2 gauges at the reg. with mech pump or a fitting as close to carb as you can get.

Me thinks you are mixing up parts on this carb, I have a number of different year Holley #1850 and all of them I have use the same needles and seats as most Hi Po Holley carbs. have
The original 1850 made for Ford OEM motors has two fuel transfer tubes, one big and one little one. The later 1850-1 with the unervisla throttel linkagesand up to the latest one I have, 1850-5 have one fuel transfer tube They all have side hung floats like you pointed out