RPM goes down

[racerx]

I have a 32/36 weber with L18, lately the RPM will go down from 800 to 500, during stop lights or idling. These are the things I did and it still does it.

 

1). Checked for vacuum leak w/ carb cleaner. Leak min. tightened all bolts on carb and intake.

 

2). Checked timing/dwell, okay.

 

3). re-adjusted carb setting, okay.

 

4). choke does not get stuck

 

Thanks for the help.

[ggzilla]

So you had a minimal leak?

 

These symptoms (idle speed varying between 500 and 800 RPM) can be cause by the carburetor or by the ignition.

* If you have points-distributor, check the distributor shaft for play.

* Check the idle screw linkage on the Weber. If something is loose this could be the cause.

* Idle port may be partially block. Remove the idle mixture screw and spray carb cleaner back up through the hole.

[racerx]

yeh some leak not much. Came from carb base. Did check the play on dist., ok...checked idle screw mech. okay, too.

[racerx]

so the car was having a hard time starting, would sputter along the way, had an extra fuel pump and changed the old one and runs okay now. RPM at idle stays at 800, no sputtering and starts, no problem. I guess my fuel pump was slowly going bad.

[ggzilla]

sounds good. Glad to hear the 510 is back on the road.

[racerx]

I checked everything, carburator (setting), coil, vacuum, linkages, dist., dwell, timing, rotor, spark plug wires, never ending with these old cars and about 3 mos. ago my pick up tube in the gas tank was plugged by a silicon, don't know how the fudge got there.

 

It's never boring..

[racerx]

Okay I think I figure this thing out.It's not the fuel pump...I called Pierce Manifold and talked to one of their techs. and he said to check the needly valve assembly. There was a lot of gas in the secondary of the carb.

 

# 19 on attached drawing:

 

http://www.carburetion.com/diags/3236DGVDiaginfo.asp

 

 

The needle valve assembly, where it screws in to the housing, was cracked..basically my carb was getting flooded because it was just letting in too much fuel and I also checked my float w/in specs of 35 mm at rest and 51 mm when you you turn the top carb. The specs for plastic and brass floats are different - so keep this in mind if you have one of these types of float.

 

luckily, I kepf my old 32/36 carb and replaced the cracked one..the car has been idling steady for about 1 week now, starting the car is no problem, does not sputter, spark plugs are not plugged up with carbon..so I will keep my fingers crossed...

 

Thanks for all of the help.

[ggzilla]

Excellent news.

[racerx]

yeh I was ready to open my wallet for a new carb...so I just checked my spark plugs and it's running clean...shit no wonder I could not adjust the carb, fuel was being dumped and would mess up my adjustment then my spark plugs would get fouled up with carbon...