Bad Power Vavle? No Power Valve!?

So, after getting my fly wheel ring gear replaced a couple days ago, I was itching to get her out on the water to test it out. Unfortunately, the test run didn't go as well as I had hoped for. To back things up a bit, before I knew I had to replace the ring gear, I was trouble shooting some engine problems that go as follows;

*Seemed to be running rich, dark exhaust smoke at idle speeds.
* intermittent power loss. Sometimes she would just quit while at decent RPMs.
* Rough idle at Low RPMS.
*Hard/Impossible to start with out adding throttle.
* quitting idling after warm.

I figured at first, it was an issue with fuel delivery in general. So I replaced the fuel pump (mechanical). This did not correct the problem though.

Having read a fair amount on this forum and others, I had come to the conclusion that it was probably a bad power valve. So I ordered a couple from SKIDIM, one to repair and one to have on hand. Just to be sure I knew what I was doing, I tore apart the original Carburetor that came with the boat (been in the barn for a decade). I found the power valve in the block of aluminum between the bowl and the main barrel section of the carburetor on the old one. Confident I knew what I was after, I took apart the Carburetor on the boat and to my surprise, there is no power valve. Just a block of filled in aluminum, and a round indentation that appears that this block was never drilled and tapped and so my existing carburetor has run for 10 years with no power valve. Unless I'm missing something, and the valve IS NOT where I think it should be?

This carburetor was a "remanufactured" unit I bought off EBay 10 years ago. Is it possible I got some cheapo version with no power valve? It's a Holly 4160. And in case you didn't know the boat is a commander 351 (1978 Ski Nautiuqe).

81nautique wrote: Which bowl did you pull, front or rear?

+1.
Also, is it for sure a marine carb and not and automotive one?

Post some pics.

As a reminder, modern marine carbs have J tubes and floats can't be adjusted externally.

Nothing really "marine" about the bowls, though it is true that Holley did not install sight holes or ext float adjustments on 650cfm and smaller marine 4160's. They did install them on 750+ cfm marine carbs though.

Float bowls can also be swapped between marine and auto carbs. J-tubes can be added or removed fairly easily. Long story short, I wouldn't assume anything about the carb you have until you pull the LIST number off the choke horn and look it up correctly- the fastest, easiest way to do that is to call he Holley tech line. If they tell you it's marine, then have them give you the part number for the proper rebuild kit while you have them on the phone.

While some people will swear up and down that the j-tubes are the only thing that makes a carb "marine" rated, I'm not so convinced. There are rumors out there that the throttle shafts are also o-ringed... And while I haven't dissected a baseplate to find out if that's 100% true or not, the only carbs I've seen with leaky throttle shafts were auto rated. They dumped some serious gas, too. I wouldn't mess around with a non-marine carb, too dangerous.

I'm not sure where the choke horn is, but I like your thinking there. So I called Holley and left a request to be called back by tech support. I don't see any ID numbers around the choke? Not on the new one, or on the old one?

It's better to upload pics to someplace like Photobucket or another photo sharing website and then upload from there. They resize them properly beforehand. Pics would sure help.

The fact that you tore apart your original carb first to know what you're looking for is an excellent start.

If it doesn't have a power valve I could see were it would be running extremely rich.

A standard 4160 Holley would have a metering bock (w/power valve and changeable metering jets) on the primary side and a metering plate (no power valve and non-changeable jets) on the secondary side. There are conversion kits that can replace the secondary metering plate with another metering block but you're talking about something that you really don't want to get into with your knowledge (no disrespect).

Yours doesn't sound right at all without a PV or what you describe as no place to even put a PV.
There are power valve plugs that can be installed in place of the power valve but this should only be done in very special competition applications which this certainly is not. If the PV is plugged, you better know what you're doing as far as tuning a carb. The metering jets need to go up at least 6-10 sizes or it'll be too lean. Yours admittedly is running rich so having what you describe just doesn't make any sense at all.

You really need to figure out how to shoot us some pics. Like Tim says, getting the list number can help us to verify what it really is too.

Float levels are usually checked during a rebuild, but they are really install-specific. Same as the idle mixture screws. Don't expect to get a new or rebuilt carb that you can just bolt on without having to adjust them.

Assuming you don't wear Velcro sneakers, you should be able to handle a float adjustment.

Well, nobody has one of those rebuild kits. Anybody got a clue where to find part number 703-66 (Holley carburetor rebuild kit)..

They were 30-40 bucks when Holley made them, and now all I have is some guy in GA from Carburetor Specialists who wants 80 bucks for one, and I'm sure that comes with another Power Valve that I can't use..

Since my buddy Rico has become proficient at rebuilding carbs, I have been allowed to start wearing them... Life is good now- thanks for the recommendation, Zach!

Glad to hear no more bending over to tie laces Timmy!

Read through this thread where we were able to walk a CCFan from Austria through adjusting a float to fix his problem. This included overcoming a language barrier.
If you still have an issue you better make a trip to Walmart and find some Velcro strapped sneakers.

I would also concur with Tom (Gottaski) about this frankencarb. Having a rebuild kit that's no longer available from the original manufacturer would certainly be enough fuel (no pun intended) to invest in a new carb. Do not go to Ebay, do not pass Go and do not collect $200. Do a search for a Quick Fuel Technology M600 carb and buy it from a reputable place and put it on. You won't be sorry.

The Quick fuel seems to be a hot item. What does it offer over the Holley other than ~50 bucks less?

If you go the QF carb way call me and I will get you a correct fuel line that will work.

I will probably be investing in a QF this spring.

Fyi, the QF is 50 cfm less than the big block holley. We threw on the QF on Mark's BBC V drive footer. Fastest the boat went before was 50.2 (Verified by Precision Star Speedo). We touched nothing on the carb other than the idle circuits. Now runs 50.4 and has extremely crisp throttle response. We need to tune timing for max power again and see if there is anything left and take a look at the plugs for mixture.

78skinautique wrote: I'm not really looking to spend 500 bucks on a whole new carburetor. If anything, I'd probably just get another remanufactured holly, or have mine rebuilt. I just brought my carburetor to a mechanic that is going to take a look at it. I told him it was running rich so first I'm just going to see if he can make an adjustment and fix it. If that doesn't work I will go from there I guess. I'm not comfortable messing with the float my self.

Then the best of luck to you.

Eddie, the M600 doesn't have 4 corned adjustment. The billet throttle body also has bushed throttle shafts which should hold up for much longer than steel on aluminum.

Also has that fuel cooling coating that makes the fuel run up to 6% cooler.

Seeing 3 of them in service here now I am pretty sold on one.