To err is human...
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 2,965
Likes: 419
From: Melbourne FL
To err is human...
and then there's me!
I've been working on my Demon carb which is giving me an off-idle, steady RPM rough running condition. I've been tweaking the IFR and IAR sizes having drilled and tapped the holes and making jets out of brass set screws.
Since I can change the IAR's without pulling the carb every time, I just stuff a rag in the venturis and unscrew the jets and screw in a different a pair. In a previous life, I worked with high speed computer equipment that often had some very small hardware, down to 2-56 and 0-80 screws. I have big hands (no reference to any other part of my anatomy!) and it's a bit difficult handing that size hardware and so you develop different techniques for doing so. One of the things we did with small set screws was dip the end of the hex driver in grease so the screw wouldn't fall off.
Now you probably know where I'm going with this! To put the set screws in the tapped IAR holes, I dipped my driver in grease and screwed them in. And strangely enough I wasn't getting any change in how it ran...in fact it ran worse!
Woke up this morning thinking about going back to original sizes to restore my baseline and sheepishly realized my error!
I've been working on my Demon carb which is giving me an off-idle, steady RPM rough running condition. I've been tweaking the IFR and IAR sizes having drilled and tapped the holes and making jets out of brass set screws.
Since I can change the IAR's without pulling the carb every time, I just stuff a rag in the venturis and unscrew the jets and screw in a different a pair. In a previous life, I worked with high speed computer equipment that often had some very small hardware, down to 2-56 and 0-80 screws. I have big hands (no reference to any other part of my anatomy!) and it's a bit difficult handing that size hardware and so you develop different techniques for doing so. One of the things we did with small set screws was dip the end of the hex driver in grease so the screw wouldn't fall off.
Now you probably know where I'm going with this! To put the set screws in the tapped IAR holes, I dipped my driver in grease and screwed them in. And strangely enough I wasn't getting any change in how it ran...in fact it ran worse!
Woke up this morning thinking about going back to original sizes to restore my baseline and sheepishly realized my error!
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 2,965
Likes: 419
From: Melbourne FL
Yes, did that but also took off the primary metering body to drill and tap the IFR holes and restore their diameter to where I started which is nowhere closer to where I'm trying to get. I'm going to have to pull the header pipe off and braze in a bung for an O2 sensor as nothing about this problem responds to what I try.
Melting Slicks
Joined: Nov 2012
Posts: 2,276
Likes: 380
From: Waltham Ma.
Many years ago when I had a carburetor car come into my shop that wasn't running good I would race the engine and put my whole hand over the top of the carb. I would do this 3 or 4 times and 90% of the time the car would run better. The suction created by blocking the top would suck any sediment out of the float bowl. I'm not saying this will work on your car but it's worth a try. Of course the reason this worked is because the carburetor float bowl was loaded with crap so the proper repair is a carb rebuild.
Last edited by biggd; Sep 29, 2017 at 08:42 AM.
