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View Full Version : So I just had my carb rebuilt...



polar21
06-03-2010, 05:34 PM
For those that have had to get a carb rebuilt, how much adjustment is needed after you bolt it back onto the boat? Other than float bowl adjustment and idle mixture, anything else that would need adjustment?

AaronWhitt82
06-03-2010, 05:58 PM
For those that have had to get a carb rebuilt, how much adjustment is needed after you bolt it back onto the boat? Other than float bowl adjustment and idle mixture, anything else that would need adjustment?

Polar -
As you have said.... Float adjustment, air/idle mixture sxrews, idle screw, choke, accelerator pump, and the secondary speed screw.
The secondary speed screw needs to be adjusted before the carb is put back on though. You want to turn the screw just enough that it just cracks the butterflies.

Here are some links to help you out:

http://www.youtube.com/watch?v=w3F3ssOb8lg&playnext_from=TL&videos=eflaCRu3Co8

http://www.youtube.com/watch?v=__3ruSX8Q_A&playnext_from=TL&videos=xWR1WyAGEBg

Aaron

maxpower220
06-03-2010, 06:46 PM
I'm confused.... if it was just rebuilt, why would you need to adjust it?

polar21
06-04-2010, 09:39 AM
Thats a good question MaxPower. I guess I could have taken the entire boat to the shop, but I just un-bolted the carb from the motor and took it to a reputable auto repair shop and had them rebuild it. Since that was the case, once I bolted it back to the motor, it was idling at 1200rpm's and it smelt like it was getting too much gas. We messed with it last night trying to dial it in but its still way out of adjustment. If you back off the idling screw, the motor will die. We messed with the idle mixture screw but it seemed to have little effect on getting the idle to around 800rpm. I am going to see about getting our boat mechanic to take a look at it if he is available, other than that I am just going to put it in the water and see if I can dial it in myself. Any other suggestions other than those two screws (idle screw on the throttle linkage side and the idle mixture screw beside the choke)?

AaronWhitt82
06-04-2010, 05:11 PM
Thats a good question MaxPower. I guess I could have taken the entire boat to the shop, but I just un-bolted the carb from the motor and took it to a reputable auto repair shop and had them rebuild it. Since that was the case, once I bolted it back to the motor, it was idling at 1200rpm's and it smelt like it was getting too much gas. We messed with it last night trying to dial it in but its still way out of adjustment. If you back off the idling screw, the motor will die. We messed with the idle mixture screw but it seemed to have little effect on getting the idle to around 800rpm. I am going to see about getting our boat mechanic to take a look at it if he is available, other than that I am just going to put it in the water and see if I can dial it in myself. Any other suggestions other than those two screws (idle screw on the throttle linkage side and the idle mixture screw beside the choke)?

All final adjustments of carbs have to be done while on the boat with the boat running in the water so you have back pressure....
After I rebuilt mine I just kind of guessed where to adjust everything at then did the final adjustment on the water. It might take you a little bit of time to get everything dialed in, but it is not that difficult.
For the float adjustment when you take the sight plug out you want the gas to just trickle out of the hole.
Also, do you know if the shop used a 2.5 power valve? Sometimes the rebuild kits don't come with those and you have to buy them seperate. My kit came with a 6.5.....
I would start with the air/idle mixture screw at about 1 1/2- 2 turns out. It would help even better if you had a vacuum gauge to do that and you could get them set about perfect....

Here is a video on how to adjust the air/idle mixture screws properly:
http://www.youtube.com/watch?v=UPGLUsW5ZeE

Holley's are also very touchy on how you adjust them.... A quarter turn of a screw one way or another could make a big difference on how the motor runs.

polar21
06-04-2010, 05:28 PM
If I had a vacuum gauge I could dial it in. We tried to tune it with the boat sitting in the driveway running (on the hose), but it needs to be in the water for best results. I am going to take the boat down to the water after work and see if I can work the kinks out.

Aaron,
I am going to take your advice and work all the screws 1 turn out and go from there. Hopefully that will get me close.

Thanks for the help everyone. I have learned a heck of alot about carbs by digging into this one.

AaronWhitt82
06-05-2010, 06:31 PM
If I had a vacuum gauge I could dial it in. We tried to tune it with the boat sitting in the driveway running (on the hose), but it needs to be in the water for best results. I am going to take the boat down to the water after work and see if I can work the kinks out.

Aaron,
I am going to take your advice and work all the screws 1 turn out and go from there. Hopefully that will get me close.

Thanks for the help everyone. I have learned a heck of alot about carbs by digging into this one.


Polar - I have mine set a little over 1 1/2 turns out. It all depends on where you live on how the carb is going to react to where you have them set. Temp., elevation and so forth are all factors to consider.
I think the youtube video mentioned it, but remember the more you turn the screws out (counter clockwise) the more fuel it will get and will run more rich... Of course the opposite way would mean that it will run more lean (less fuel...)
Also remember the air/idle mixture screws only control your Idle circuit.
I would rather have the boat run a bit more rich at idle than lean, but thats just me.