I have a Holley 4160 that's got me stumped. It's a 600cfm with a manual choke on a '76 F250 360/390 (not sure which). I bought it used to replace a 750cfm carb that was too big for the engine.

I went through the carb and put a genuine Holley kit in it before I installed it. It ran fine, but for some reason the secondary side wants to flood intermittently, no matter where the float is set. It might flood every 5 minutes, or 5 days. It might flood on a cold start, or after a couple hours of driving. There's no pattern to it.
I pulled it off yesterday to re-jet it, and while I had it off I put new brass floats in both sides and thoroughly checked out the secondary bowl. The needle/seat was cranked down as far as it could go, but it was still flooding occasionally. Everything was fine in the bowl- float isn't binding, bump spring is in place, baffle is OK, needle and seat are as clean as a whistle and the o-ring is OK. So I put the new float in and put it back together. (it has the side-hung bowls, BTW)

Same problem. The primary side is fine, but the secondary side wants to keep flooding. I can get the fuel level down to where it isn't gushing out of the sight plug hole as hard, but I can't get it down to the "dribble" like the primary side.
I haven't checked the fuel pressure, but it's just a stock mechanical pump, and it seems to me it would probably flood both sides if the pressure was too high.
I put the old needle/seat back in just in case the new one was bad. No help. The float is new, and the old one was OK anyway.
I thought about a smaller needle/seat, but I shouldn't have to do that. I think the problem is in the secondary metering side of the carb. It doesn't seem to be pulling any fuel on that side, and it should pull enough on it's idle circuit to maintain the fuel level in the bowl. I could've used the wrong gasket for the metering block or plate, since the kit had more than one (just a guess). But I suspect that the secondaries aren't working right anyway. I can't hear them open when I jam on the gas while I'm driving. The secondary butterflies aren't binding when the carb is off the engine, but they seem to be tough to move by hand when the engine is running. But I just figured that was the diaphragm fighting me.
Any help or suggestions would be appreciated. This thing is starting to get on my nerves.

 

I'm not an EXPERT, but I know about Holleys. As for the secondaries you could have a slight bind in the spring pod or that area. Also too strong of spring if they aren't working. As for the flooding it almost has to be the NEEDLE & SEAT, or YOU USED THE WRONG GASKETS. That's what I'm thinking as of now.

 

Pehaps the needle and seat is bad or the bowl has a spot in it the is not letting the o-ring on the outside of the needle and seat seal off correctly.

 

Well, I tried two different needle/seats. No difference. I should probably take a good look at the bore where it threads in, like LX said. The fuel might be leaking around the needle/seat rather than through it. BUT- If I crack the needle adjuster lock screw open right after shutting the engine down, the gas sprays out under pressure. So the needle is holding pressure, at least some times. It also adjusts really easy- easier than the primary side. I can adjust it easily with two fingers without using a wrench. Maybe it's too easy 'cuz of a worn bore.

Since the Holley kits have extra gaskets, I might have gotten faked out and used the wrong one, or put it in backward. I'd like to convert it to the 4150 style, but this is a used, beat-up piece of crap carb and I don't want to dump a fortune into it.

Thanks for the help. Any more info would be appreciated.

 

I had worn threads in the bowl that acted this way. They were there, but after close examination I observed that the needle and seat could move with little effort. The float was pushing them out of the bowl. A used bowl off a parts carb fixed that problem.

 

Maybe a thicker o-ring will fix it.

 

Is the spring installed between the float? If you have to buy a new bowl Jegs has the old style for I believe $24. I just helped my friend install a new primary bowl because the screw holes where stripped on the accelerater pump.

 

Yeah, the bump spring is good. I'll tear into it tomorrow after I get new metering plate and bowl gaskets. Keep ya posted. I'm sure everybody is on the edge of their seats.

 

All 4160s should use the same metering plate & bowl gaskets. What where the 2 different types in your rebuild kit?

 

I have the remains of 2 kits sitting around.......one for a center-hung 750 that I rebuilt and one for the 600 that's on the truck now. There's a new plate gasket in the pile of leftover parts, but I don't know which kit it came out of. The new one I just picked up looks just like the leftover one.
There was a ton of extra parts in the renew kit, thanks to Holley's part # consolidation. Great for the guy selling it, slightly confusing for the guy doing the rebuild.

Stay tuned.

 

Yea, I hear you. It seems like anymore a lot of things are getting harder not easier. I sometimes think they want us to get rid of our PAID FOR older cars & trucks. Isn't it the AMERICAN DREAM to be up to our A$$ in debt? That's what my TV says 5,000 times a night.

 

OK, everybody can breathe easier now.

I found a crack inside the secondary bowl right where the inlet from the balance tube is. It was leaking gas into the bowl directly from the passage ahead of the needle and seat. It was really hard to spot- I had to hold the bowl at just the right angle with really good light to see it.
I had a 750 with center-hung bowls sitting around, so I scabbed the bowls from that onto the 600, along with the dual inlet setup. I like the center hung bowls better anyway. Makes the carb look meaner, and it eliminates a potential source of leaks in that balance tube.
Haven't driven it yet, but I ran it for a while with no probs. I couldn't even keep it running when I started it a couple days ago.

 

Good deal, I hope it works out for ya