'65 evinude 18hp carb mystery

[jbjennings]

Guys,
I have been trying to fix this danged motor for a while! I have finally gotten the problem narrowed down to the carburetor, specifically the top carburetor half. I finally resorted to putting my top carb half from one of my '57 18's on it and it ran great. I have blown out, even taken the welch plug out, and cleaned and cleaned on the passages. The idle needle end looks great. It just will not run right. The float also doesn't seem to close properly even though it's a brand new float, valve, and seat. If I turn the idle needle all the way seated it won't die. If I place my hand and even attempt to block the carb throat, it will die.
Can anyone give me any ideas on what I'm doing wrong. I've done quite a few carbs lately with success, but this thing is really getting to me.
Thanks,
JBJ

 

[Faztbullet]

Re: '65 evinude 18hp carb mystery

Did ya replace the plastic needle bearing??

 

[samo_ott]

Re: '65 evinude 18hp carb mystery

Leave the '57 top half on it and don't stress about it!

 

[F_R]

Re: '65 evinude 18hp carb mystery

Somebody plugged up the bowl vent???

 

[tmcalavy]

Re: '65 evinude 18hp carb mystery

Yup, that's what I'd do...some carbs have been fiddled with so much that you can't get them tuned right because of the former owner's good intentions gone wrong. I'd find a replacement off an 18 from the late 50's, and keep the problem child for parts.

 

[jbjennings]

Re: '65 evinude 18hp carb mystery

Did ya replace the plastic needle bearing??

Faztbullet,
I'm embarassed but I don't know what a plastic needle bearing is, so no I didn't replace it. Could you tell me what that is, where it goes, and what it does?

Thanks,
JBJ

By the way, Steve, it's my frat. brother's motor, and my good '57 carb! I don't want to "part" with it!

 

[F_R]

Re: '65 evinude 18hp carb mystery

I'm not too sure the '65 has a needle valve bearing. Does it have a packing nut on the idle needle? If it does, there is no bearing.

 

[jbjennings]

Re: '65 evinude 18hp carb mystery

Yes,
It does have a packing nut. Definitely not a plugged bowl vent. One more symptom: It's not getting enough air or too much fuel because when I take my air compressor and blow some air into the carb, fuel pours our the bowl vent and the motor runs faster/smoother at idle. Also, the motor will not run on choke at all. Also, turning the low speed needle in all the way won't kill it.
I know it's something simple but I just can't figure it out. It's got a new float needle/seat/float/float needle clip too.
Baffled,
JBJ

 

[Faztbullet]

Re: '65 evinude 18hp carb mystery

On most of the small carbs in the very rear is a white plastic bearing that seals around the needle(#28). See attached pic, hope this might help.

 

[cando67]

Re: '65 evinude 18hp carb mystery

not to sure but it sounds like the check valve (even if it is new) may not be seating well and letting too much gas in. if the top off the other is working try a new seat and check and do not over torque the seat. hope this helps