Advice on Carburetor Rebuild

Pat, Wecome to the site. Glad you found us.

To me, it sounds like a accelerator pump issue in the carb and getting the whole thing rebuilt may be premature. Are you set up to run it at home on the trailer? Do you have any motor head friends?!!

The accelerator pump squirts some raw gas down the intake when you mash down the throttle. You can see it squirt with the flame arrestor removed from the top of the carb. I have seen the accelerator pump seal/packing gland dry out when a boat sits for extended times without gas in the carb. They can swell back up after a few days!! Has the boat been stored for any time?

I know that other members here will comment on the problem as well. We've got plenty of knowledgeable people!

Got to get us some pictures!

timing is the first thing I would check. The accel pump is easy just move the throttle at the carb and watch if it doesn't squirt emediately(sp) then adjust it untill it does it's a realy easy and quick adjustment to make.

Thanks all for the quick feedback. Here is what I know and what's been done so far. Bought the boat June 07. Used it last season and put about 50 hours on. I am pretty sure the boat sat in storage for a number of years but was always winterized every year. The previous owner always thought he would use it but.... It was tuned up last year and the electronic distributor added. I replaced the prop with the spare that I had reworked. In general the boat runs very well and does not stall, hestitate or skip etc under no load conditions and starts easily. It just seems to hestiate when pulling a big skier (boarder) 200lbs+ up, but not all the time. You begin to accererate and the motor just dies and then picks up before you can back off or any thing. I played with the air mixture all last season to no effect. We are teaching lots of new people how to ski and board it is very annoying. Do not want to get into the season without a fix so I am willing to some extent to shotgun the fix. I will replace plugs and wires this spring. I replaced the fuel filter last fall when I winterizied. I think it must be in the carb but I don't think I can be sure if I fixed the problem on the trailer because of the load problem. Is a carb rebuild a possible solution and if so has anybody had experience with the shops in my first post.

Another possibility is the power valve. The valve could be sticking or could be a bit too small. I think the stock set-up uses a 2.5 (vacuum needs to drop to 2.5"Hg before the PV opens) Many move to a 6.5 or greater. This gives a rich mixture earlier and could avoid the momentary lag you describe. Getting at the power valve is fairly easy....it sits in the metering body just behind the primary float bowl.

pat86 wrote: I played with the air mixture all last season to no effect.

Take the advice posted and verify the timing, the condition of the plugs and wires. Replace if necessary. Did you set the idle mixture when the engine was warmed up and in gear? That needs to be done.

LaurelLakeSkier wrote: TRBenj wrote: LaurelLakeSkier wrote: I think the stock set-up uses a 2.5 PV 6.5 is usually the stock PV. The 2.5 has commonly been shipping with the SkiDIM rebuild kits, but the 6.5 is preferable in most cases. Thanks for the correction Tim.

I'm not one to disagree with Tim but I think LLSkier is correct, although most agree the 6.5 is a better performer. I've torn 2 stock 4160s apart and both had a 2.5 PV inside, the rebuild kits do come with the 2.5 so I am "guessing" that is how they are outfitted originally. My rebuilds get a 6.5 for about $8.

I have to fill you guys in on LLS. He has a college degree in power mechanics and teaches the same. Now, I have seen plenty (most) of teachers who may do a good job at the actual teaching but when the time comes to get their hands dirty, it's a completely different story!! LLS is one of the exceptions!

Mark, What did you end up doing with your valve adjustment? You sort of left us hanging unless I missed something!

the holley re-new kit that I bought had the 6.5 PV and that was based of the carb's numbers not the generic 4150 number.

Timmy I got your WEE right here..If you have not done a plug check , you are assuming, and with that you have no idea of the correct PV. You are guessing what the cruise mixture actually is.
And back to my Wee motor , if the math is correct you motor is only 6.1 percent larger. And if my research on data is correct I make more HP and more torque than your motor.And the air flow is almost the same.All of this with a WEE motor.
But you know best Timmy , you have been on the site longer.........Boat dr

Doc, youre dealing with a wee 331 ci, which I assumed was the reason why the smaller PV worked better in the larger 600cfm carb. Im happy with the responsiveness and theres no indication that Im running rich- but youre right, a plug chop wouldnt hurt anything. Ill add it to my to-do list.[/QUOTE]

Doc, it may be an assumption, but it is based on good theory. Greater flowing heads and intake = less vaccuum, and I didnt want the PV coming in late.

boat dr wrote:    And back to my Wee motor , if the math is correct you motor is only 6.1 percent larger. And if my research on data is correct I make more HP and more torque than your motor.

Your memory may be good, but your math is suspect! With 20 more cubes, more compression, better flow (intake and heads), and RR's, I dont see how youve got me beat. You should just be thankful that my powerplant is pushing a 19.5' tank!

I got a Holley kit from Skidim for my 4160 and it came with a 2.5 PV.

I have not rebuilt my carb yet, hopefully in a few months.

But Allen is that a marine Kit? looks like the auto version to me.




So maybe that is why you get the 2.5 PV instead of the 6.5 PV because when I bought my HOLLEY MARINE kit from Rex Marine it came with the 6.5 PV in the kit your not rebuilding a car's carb your building a boat's carb and they are set up differently.

79nautique wrote: But Allen is that a marine Kit? looks like the auto version to me. So maybe that is why you get the 2.5 PV instead of the 6.5 PV because when I bought my HOLLEY MARINE kit from Rex Marine it came with the 6.5 PV in the kit your not rebuilding a car's carb your building a boat's carb and they are set up differently.

Chris, I give, you win. I bought the damn kit from an inboard marine dealer so maybe I assumed it was a marine kit and it isn't. I don't really know and don't give a rats ass. If it's that big a deal to you give Skidim a call and ask them yourself.

Ps, I deleted a whole bunch of expletives , if you want them in person give me a call.

Doc, we've been over this- I owned the blue boat out of the hole and you were nowhere to be found when we were running around on Sat. Motor for motor, I better be stronger than you- Ive got a lot more boat to push! No excuses here- we'll see how many footers it will pull in 5 weeks time. Im always after speed, but the boat was built to pull. Whether youre impressed or not makes no difference to me, but you didnt line up with me nor take it for a spin, so youre a little quick to pass judgement.

Unless Im mistaken, the 2.5 PV youve got in there now cleared up a midrange stumble, did it not? Im not saying I wouldnt benefit from a swap one way or the other, but Ive got no such symptoms to speak of.

Ive got 2 Holley marine kits and one PCM for various List numbers in my basement- Ill crack them open tonight and note the PV size, just for kicks.

Chris, he's got me by 10mph on the top end, no question. Holeshot should be close, but Im not conceding it until we line it up. My argument is that my engine should be a touch stronger- put it in a comparable hull and I like my chances. Its a moot point, I suppose, since the boats were built with very different purposes in mind.

You had me on the top end by a few MPH, but I beat you so bad out of the hole, it took you a half mile to catch up!