SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: jsouza3 on April 07, 2016, 09:47:21 AM
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Hey guys,
Just pulled the boat out last weekend and starting to get her ready.
The last few trips last year I was having trouble with the carb, floats sticking and bowl gaskets leaking. So I need to rebuild it. It hasn't been touched in about 12 years from what the previous owner told me. It is a list#9188. I've done some research and it's a 4150 750 cfm. I'm going to pick up the rebuild kit at the local parts store and give it a whirl.
I've never rebuilt a carb before so I'm looking for some hints and tips. Any input would help.
Thanks for your guys help!
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It's pretty straight forward, you'll see as you take it apart. Take some pictures so you know. You'll need a clutch head screwdriver to take off the secondary metering plate. You can also get away with using a flat head screwdriver if you grind it down just right to fit.
Also the rebuild kit doesn't come with a new diaphragm for the vac secondaries. I like to replace that too when I rebuild. It's about 10 bucks at the parts store.
If it's really bad inside you'll probably have to soak it for a day or so in carb cleaner.
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Scratch that clutch head screwdriver bit, wrong model Holley I was thinking of.
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Getting ready to do mine this weekend
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Getting ready to do mine this weekend
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Nice. Where did you get your rebuild kit at?
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It's pretty straight forward, you'll see as you take it apart. Take some pictures so you know. You'll need a clutch head screwdriver to take off the secondary metering plate. You can also get away with using a flat head screwdriver if you grind it down just right to fit.
Also the rebuild kit doesn't come with a new diaphragm for the vac secondaries. I like to replace that too when I rebuild. It's about 10 bucks at the parts store.
If it's really bad inside you'll probably have to soak it for a day or so in carb cleaner.
Thanks for your input. I've tried a couple of parts stores here in town and I was surprised that they didn't have them in stock. Seems like a pretty common kit. I have found plenty online but would rather buy them locally.
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I'm going to recommend using a genuine Holley kit or one from a clone brand. DO NOT use a generic carb kit from the local parts store because the replacement needle and seat assemblies will cause damage to the bowl.
[attachimg=1]
This style uses a jam nut to tighten everything down and can strip the threads if over tightened.
[attachimg=2]
[attachimg=3]
The factory Holley parts use the nut as an adjuster and the screw as the lock. This design will not allow you to strip the threads when used properly.
Good luck with the rebuild.
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O'reillys sells the Holley brand kits, best price I can find in town too and only like 4 bucks more than ordering straight from Holley.
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Got my kits through Summit Racing
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So I finished the rebuild a couple of weeks ago and got everything back in the boat. I went out to the lake this Sunday and for the most part it ran well. Much better than the last few trips Last year. The boat fired right up but idled a little rough. I adjusted the idle mixture screws and sped up the idle to around 800 rpms just to keep her going and warm it up.
At low RPMS and WOT the motor is running good. It seems to be at half throttle acceleration up to WOT that it is stumbling a bit.(kinda like it's running itself out of fuel). Would that be the accelerator pump? Do I need To Adjust the bowls up a bit more? I thought I had the bowls set right. The fuel is right at the sight hole when you take the plug out. All in all it was a great day at the lake.
Any help would be appreciated. Thanks!
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The spring for the secondary diaphragm has a colored stripe on it, did you notice what color was in it?
Also, what power valves did you put in it?
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I do not recall seeing a color on the spring, I can pull it out and check if that's critical info. As far as the power valves I put in, I'm not exactly sure on model or number. I just used the ones that were supplied in the kit.
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I do not recall seeing a color on the spring, I can pull it out and check if that's critical info. As far as the power valves I put in, I'm not exactly sure on model or number. I just used the ones that were supplied in the kit.
You need to lower the power valve rating.
The spring is less important for part throttle running, I would be inclined to say it's neading to be fattened up, bit running fuel pressure is silly important.
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Okay do you have any suggestions on what to lower the power valve too? I have also noticed that I'm using a lot more fuel than I ever have, is that caused by the power valve rating being too high also? I was at the lake Yesterday and burned through one of my 25 gallon tanks and I have never done that. I did have a load on the boat and I'm not easy on the throttle, but was surprised to see how much fuel I used.
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Okay do you have any suggestions on what to lower the power valve too? I have also noticed that I'm using a lot more fuel than I ever have, is that caused by the power valve rating being too high also? I was at the lake Yesterday and burned through one of my 25 gallon tanks and I have never done that. I did have a load on the boat and I'm not easy on the throttle, but was surprised to see how much fuel I used.
In 90% of the ones I've done, I start with a 4.5, without knowing where the manifold vacuum is at a good cruise rpm, it's nearly impossible to guess. Grab a 4.0, a 4.5 and a 5 and a vacuum Guage and go screw around with it.
I bet a 4.5 is really close.
GT
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Thanks for the info. I'll try to find out what size I put in it to begin with and go from there. Would that explain the using too much gas and running a little rich?