4160 holley needle and seat for PCM 351W

[horkn]

What size needle and seat combo would a 600cfm 4160 need?

Holley makes a couple sizes. 0.110" Seat, and 0.0785 in. Seat Size. I would need non adjustable right?

I installed a new marine fuel pump from DIM, along with a new fuel water separator filter and the psi is actually higher than the pump I had on for a test pump. This one does 7.5- 8 psi. I was kind of shocked it would be that high.
the carb does not always seat and drops of gas come out of the venturi at idle sometimes after revving it up a bit. When it does not drip, it runs perfectly smooth, but when it drips from the venturi(s) the idle is not consistent.
I'm thinking because of the higher psi from the marine pump, it is forcing a little gas past the seat and needle.

Am I right assuming napa will have this?

[skijones]

If you are going to get that far into it, you might want to get a rebuild kit. Usually about $25.

[horkn]

The carb has been rebuilt only 2 years back. Otherwise I agree with you and would rebuild the whole carb. I think the needle and seat degraded from then, so buying a rebuild kit seems a little excessive.

Where have you found them for 25 dollars? I have only sen them for about 50.

[Rick]

Pressure regukater

I don't remember the specs on a 4160 but 7.5psi seems a little high You might want to try an inline regulator that you can turn down until the leak stops and the boat still runs. I haven't seen a needle and seat deteriorate that it wouldn't work under the right fuel pressure.

[horkn]

I was thinking of putting an inline regulator on ti, but on CCF, the mere mention of a regulator started a debate. I'm just wondering why a new fuel pump for this application would run such a high psi?

I'm going to take off the primary bowl and inspect for crud. That might be the issue. The old fuel water separator / filter was pretty full of crap.

[skijones]

That is your problem. Change the filter, again, run the boat and tap on the fuel bowl with the plastic end of a screwdriver, not hard. Chances are that will solve it. You will probably need new gaskets if you pull the fuel bowl, so it's easier to get the kit. BTW, quite a few of my buddies have carbed boats, so I usually have one or two kits in my garage. Just bring cold beverages and we are in business.

It takes just a miniscule piece of anything to make a needle valve leak. Kind of overkill, but I change my fuel filter every season. Peace of mind.

I get my kits from NAPA, but I do have a commercial account with them and spend a whole lot of money every month.

You don't want to do it in the middle of the season, but it might be time to pull the tank and have it cleaned out. If the leak is not fixed, the excess gas will wash down the cylinder walls and the next time it is started, you will have excessive wear on the cylinders and pistons.

I have 750 hrs on my current boat, 99 open bow, but have seen these motors go to 2500+ hrs with no rebuild. Take care of the little things and they will not turn out to be big things.

[horkn]

The filter is new, I don't see that as an issue with maybe a half hour of run time on it.

I pulled the bowl (I have reusable bowl gaskets) disassembled the float and used a swab to check the seat for gunk. There was no crud on the seat, and I wiped off the viton needle as well. That looked clean as well.


I looked today what it was running for fuel psi, and it was 8-8.5 psi. I am really thinking that the pump is simply putting out too much pressure.

I have an email in to DIM. I will see what they say.

I do know of someone else with a CC that just bought a new pump from DIM and they were having the same issues after the new pump, although they did not have a pressure gauge as they assumed the new pump would be putting out the proper psi.

Yeah, I know excess gas from carb is not good. The dripping does not always occur, even at that high of psi. Also, as soon as the motor is stopped, the dripping stops as well. That also tells me the PSI is too much and the needle isn't the real issue.

[gjs90SportNautique]

It has been a few years on this but I had the same problem with dripping on port side at idle. And thought this may help someone.
At spring start up I did end up running it out of fuel.

I rebuilt the Holley 4160 carb last year and it ran fine.

This year it ran fine until I ran out of fuel and then I Had the dripping at idle. witha really rough idle.
Pulled the bowl and metering block used carb cleaner and compressed air on all the parts and holes. .
Reassembled and had same problem.
Took it apart again This time I checked the screen filter where the fuel line connects, it was open on one side. So I assume some crap got in even though I have a spin on fuel filter. Fixed that.

The power valve and accelerator pump were fine. I pulled the float and held it under water, no leaking.
The needle looked fine but I had kept the old ones from the rebuild and decided to try one of them. Reassembled and it ran fine, no dripping at idle.

So the moral may be check/clean and then double check/clean