Carburetor problem, running rich at idle

I just had my carb rebuilt and it was a 6.5 put in not a 8.NOt sure how much of a difference that would make but someone on forum will.

Change in PV should have zero effect on the idle, else its an indication you have things way out of sorts.

The 8 will give you problems you haven't encountered yet because the state of tune is still way out.

Sounds like you are still not idling on the correct circuit.

The idle fuel orifices in the metering block are likely still clogged.

If there was that much junk in the carb, you need to aggressively address fuel tank quality and filtration else even a new carb will go to crap in few minutes.

Guys, thanks a bunch for all the comments! They are much appreciated.

Chris74 wrote: I just had my carb rebuilt and it was a 6.5 put in not a 8.NOt sure how much of a difference that would make but someone on forum will.

Good to know, thanks. It sounds like the 6.5 was correct after all.

Waterdog wrote: Have you closed the idle mixture screws one at a time ? The idle circuit should stand on it's own. Without help from the transition circuit. It should really change the idle quality and or kill the engine.

Yes, we did try this before, and I just tried it again a few minutes ago. The mixture screws obviously are doing something, because turning them does have an effect. Right now, closing them all the way actually makes the engine run better at idle because it is way too rich with them open. Something else is dumping way too much gas into the engine at idle.

GottaSki wrote: Change in PV should have zero effect on the idle, else its an indication you have things way out of sorts. The 8 will give you problems you haven't encountered yet because the state of tune is still way out. Sounds like you are still not idling on the correct circuit. The idle fuel orifices in the metering block are likely still clogged. If there was that much junk in the carb, you need to aggressively address fuel tank quality and filtration else even a new carb will go to crap in few minutes.

I think you are correct in saying something is way out of sorts. What that is, I have no idea. It sounds like the 6.5 power valve was the way to go, so I will swap that back in. What would cause the main circuit to be dripping gas at idle? I can see it coming out of the nozzles in the front two barrels. I don't think any of the junk we cleaned out of the carburetor came from the the fuel tank, though I could certainly be wrong - it looks like dried out ethanol gas.

Lakeview wrote: What size jets are you running ? #65 0r #66 should be adequate-did you replace the float needle valves?and seats? When you rebuilt the carb did you use carb cleaner and blow all the passages out with compressed air? Lots of info out there on tuning Holley Carbs-took me lots of tweaking to dial mine in-Good Luck

I will check on the jets when I pull the carb again tonight - they would be whatever was installed from the factory. Float needle valves and seats were replaced. I'm going to make sure they look like they are functioning correctly when it is apart. All of the passages were thoroughly blown out with both carb cleaner and compressed air during the rebuild.

I have some time tonight to look at it more and will reply with any updates. Thanks again!

The drips at idle on the primaries are due to the clogged idle fuel orifices.

Your idle stop is now opened too much because to the idle circuit is clogged and that's the only way your getting it to 'idle'.

Your idling now on the transition slots instead, and these pull fuel from the main jets.

The causes air from the main bleeds to percolate the raw fuel up to main boosters and cause the drips you see.

I believe your metering block is still clogged inside, and will never operate well at idle until you clean them or replace the metering block.

Your symptoms may be compounded my vacuum leaks. Hopefully you use fresh fel pro 1901 base gaskets, and not the crap in the rebuild kit.

Hi everyone, thanks for all the help. I really do appreciate it. Things are really busy right now, and this whole mess is not really what I wanted to deal with, haha

My dad and I ran the boat some more tonight and we messed with the floats some. I now cannot see gas dripping from the front two nozzles, so that is an improvement. It ran better, but would still idle with the idle screws screwed in all the way (and in fact idled best like that). It seems like one of the other circuits is still letting in gas when it is not supposed to. I know at least some of it is coming in through the rear two barrels, because I can see it pooling on top of the rear two throttle blades at idle. It's not coming out of the nozzles - there is a small slit right at the level of the blades that it comes out of. I used carb cleaner to follow the passageway, and it seems these are connected to the rear metering block.

I messed with the rear float level, but lowering it didn't really seem to decrease the fuel flow. I still need to test the needle valves to make sure that is working.

Also, the engine runs really rough - it shakes the whole boat. Is this a symptom of the fuel being too rich?

Tilleryboy wrote: If the secondaries are dripping fuel at idle either the rear metering block gasket is leaking or the rear float is stuck. I had the same problem with the metering block gasket.

I don't think the float is stuck because it moves pretty freely. I will look at the metering block gasket when I get another chance to mess with the boat.

GottaSki wrote: The drips at idle on the primaries are due to the clogged idle fuel orifices. Your idle stop is now opened too much because to the idle circuit is clogged and that's the only way your getting it to 'idle'. Your idling now on the transition slots instead, and these pull fuel from the main jets. The causes air from the main bleeds to percolate the raw fuel up to main boosters and cause the drips you see. I believe your metering block is still clogged inside, and will never operate well at idle until you clean them or replace the metering block. Your symptoms may be compounded my vacuum leaks. Hopefully you use fresh fel pro 1901 base gaskets, and not the crap in the rebuild kit.

I think you are right on the first part, except that I don't think the idle circuit is clogged. I have cleaned everything several times now, and it was idling okay before the rebuild, though not great. When the screws are open, more gas smoke comes out the exhaust and it bogs down. What are the "transition slots"? Are they the slots I mentioned above right by the the throttle blades?

Dreaming wrote: Since there is gas dripping, and you just rebuilt the carburetors, I would suggest checking the float adjustment level.    the Carburetor needle and seat valve shuts off the fuel when the float comes up the the appropriate level, so if the float is not adjusted properly, or t he needle and seat valve is leaking when the float is in the up position, gas will continue to dump into the carburetor.   If you have dripping fuel, the gas level is too high,   Bend the tab on the float down a touch to remedy the issue. This may require several small adjustments, as the engine is sitting at an angle. The Holley measurement for float level may need to be modified slightly to accommodate.   If you modify too much, the fuel level in the bowl will be too low, and you will have lean running issues.     The front barrels are the secondary's, so start with the float on that side, and check the primary also. While you have the bowls off, check the needle and seat by blowing into the fuel inlet (by mouth) to see if you can stop the fuel inlet by raising the float up to it's shut off point. The transition circuit comments are a good suggestion also, but you need to fix this dripping problem first, or you won't get a good read on the transition circuits.

Thanks for this comment. Adjusting the floats seems to have helped. Any ideas on what's up with the rear bowl still leaking at idle through those slots by the rear throttle blade? Adjusting the rear float didn't seem to decrease the flow.

Thanks again for all the help! Also if there are any good books or websites on how these carbs work, please let me know. The stuff I have found on the internet so far has been helpful but far from comprehensive.

David

SummitRacing.com produced several videos called "Quick Flicks" on various subjects -- including Holley carburetor tuning, etc. Go to YouTube.com and type the following in the Search Box:

"summit racing carb quick flicks"

Happy viewing.

JQ

Howdy guys, sorry for the long wait for a reply. Thanks a bunch for the tuning resources! Those videos on YouTube were helpful.

Anyway, we finally figured out what the problem was. The metering block gasket in the rebuild kit was incorrect, and was allowing gas to flow directly into the engine from the rear bowl. Once the old gasket was put back in and the the oil changed (there were like two quarts of gasoline in the oil from all the testing), it ran completely different. It fires right up now, and will die immediately if the idle adjustment screws are tightened all the way. Idles better than it has in a long time. Hopefully we can pick up a vacuum gauge and really dial in the tune this week.

Got to ski behind it on Sunday, so it made all the frustration worth it! I think I got the diary link working correctly, so I finally got a picture of the boat up. Thanks again for all the help and encouragement!

Gasket Photo