Various carb questions

I'm packaging several questions into one convenient post here.

351 w/4160. Last rebuild of carb unknown. Boat runs very well right up to WOT. Great hole shot, great WOT, the whole bit. Starts and hot/cold idle can be rough and at idle the boat will eventually choke itself out with an overly rich mixture after a few minutes of idling. Idle adjustment screws do basically nothing. Culprit found to be primary dripping gas during idle and after shut-down. I understand this to be a bad float, a gunked up needle valve, or a mis-adjusted float.

1. SO. Do I just take off the front bowl and attack the primary float/valve issue OR...

2. Do the WHOLE rebuild kit while I have it?

And

3. When I put the carb back onto the boat, do I have to "prime" it somehow to fill up the float bowls, accel pump, etc?

4. Any gasket sealer on gasket to manifold?

ALSO

5. The motor appears to have this heat shield under the carb. The gasket below it is pretty thick, potentially a stack of gaskets though reading this it looks like it comes with a thick lower gasket and that's probably what it is. Is this necessary?

6. I saw updated bowl screws on Skidim. Do I need these? The carb I have has flathead screws holding the bowls on

7. Anything else I should do "while I'm in there"?

Ditto what Gary said. Idle screws unresponsive = plugged idle passages, so you're pulling off the front bowl and metering block to clean and blow out. Might as well do the back bowl at the same time. Grab the list number off the choke horn and call Holley to find out which rebuild kit you need... Make sure they point you to one with the reusable (blue) gaskets. Don't forget to pick up carb cleaner and a few cans of compressed air if you don't have a compressor up north!

You'll need 5/8" and 1" wrenches for the fuel line. Pick up some JB weld just in case the soldered plugs weep after the rebuild (this is common). I'd ditch the heat shield.

I also concur. Do the whole rebuild.

I might add one other helpful hint. Pouring some gas in the carb throat to initially start it does work but can be a little dangerous. I've done it before myself.
I've started pouring a small amount of gas in a cup of some sort. If you have access to a small syringe, you fill it with the gas from the cup and then squirt it into the vent tube. Repeat several times. Now you need a syringe small enough to be able to fit in that small area between the vent tube and the choke horn but it does the job.

Nice writeup catamount. Thanks for sharing. That ultrasonic cleaner really did a good job. I see it at Harbor Freight for $79.99.
Here's another writeup done for an 88 SN 2001.

Awesome thread Catamount. That's the best 4160 rebuild writeup I've ever seen.

Couple of nice looking Prostars as well.

Justin I just purchased the same ultrasonic parts washer at Harbor Freight last night ($66.xx with coupon). I'll be using it to clean my carb and various parts this weekend.

Thanks guys. And OP, great work rebuilding yours! It's satisfying for sure.

ny_nautique wrote: Justin I just purchased the same ultrasonic parts washer at Harbor Freight last night ($66.xx with coupon). I'll be using it to clean my carb and various parts this weekend.

Hey, that is really cool! I think you'll like it.

This is a Keihin motorcycle carb I cleaned this past winter. I use a 3 part water, 1 part Simple Green solution. There are lots of other suggestions out there as far as solutions go.

This carb was caked in grime before I gave it a long bath in the ultrasonic. When it came out, it looked new.



One note, if you put aluminum parts in with Simple Green be sure to turn them every 10 minutes or they may get stain lines.