Throttle Shutter gap???

[further]

Just finished re-assembling my second carb and noticed that when I put in the throttle shutter there appears to be a slight gap at the top of the shutter and the carb body (i can see daylight). The first carb I put back together does not have this gap. Is this ok to leave or is something wrong??? I have it on correctly as I've triple checked (really hard to screw that up - right side up, numbers facing out).
Thanks for the help

 

[john from md]

Re: Throttle Shutter gap???

The trottle plates should be closed with the carb in your hand. The idle adjusment is made with the idle cam to open the plate enough for starting.

Put a piece of paper under the throttle plate and let it close. The paper should drag coming out. If it doesn't, look for a bent bellcrank or spring at the spring end.

John

 

[pnwboat]

Re: Throttle Shutter gap???

If you removed the throttle shutter or butterfly plate, you need to align the plate. To do so, loosen the two screws that hold it into place so that the throttle shutter can move freely. Allow the shutter to close. Adjust the shutter so that you do not see any gap. Tighten the two screws.

Sometimes the shutter or plate binds up when you reinsert them into the slot in the shaft so you have to fiddle with them to get them to close properly.

 

[further]

Re: Throttle Shutter gap???

Ok, will try to adjust but doesn't seem like there is much room for adjustment. I'll try to take a photo and post it tonight as well. John, the issue is not at the bottom of the plate it is on the top side where I can see daylight between the top of the plate/shutter and carb body.
I never thought rebuilding carbs would be so much fun!!!:redface:
Thanks again.

 

[john from md]

Re: Throttle Shutter gap???

Unless damaged, most mechs don't disassemble the throttle and choke butterflys. If you did, that is probably how they became misaligned. Take pnwboats advice, loosen the screws and let the valve center itself. As it is under spring tension, it should self align to the bore of the carb. This assumes that you put it back in the same direction it came off.

John

 

[further]

Re: Throttle Shutter gap???

Ok, will do. Love how the manual says to do it but there's really no reason to which i can see now. What would be the effects of this gap becuase I think it existing before i took it apart. If you recall, I am working on the carbs because I couldn't get rpms up fro 4500 no matter what pitch prop i used (15 or 17) and could only get 30mph. I've also found that my floats were not properly aligned.

 

[pnwboat]

Re: Throttle Shutter gap???

Most likely affect idle and possibly low speed. Once you open the throttle, there's a real big gap...

If floats were set too low, you may see a lean condition...not enough gas getting to motor.

If floats were set too high, then you would see a rich condition...too much gas going into motor.

Either way it would affect the motor depending on how far off the floats were.

 

[Frank Acampora]

Re: Throttle Shutter gap???

The butterflies are beveled so they contact the casting properly when closed. If you put them in backwards, they will not fit properly. They only go in one way but can be assembled the wrong way. It is easy to put them in wrong. Double check and be certain the beveled edge is facing the correct way.

 

[further]

Re: Throttle Shutter gap???

Yes, i loosened the screws and let the shutter set itself flush then re-tightened. There is definitly some adjustment - its no set flush. My manual says to keep the numbers facing out and has good illustrations as to which way is right side up. I also kept one carb assembled while putting together the other two for reference.
Thanks for the help everyone. Couldn't do this without ya!