1954 Cylinders 3 & 4 carbon fouled

[David W.]

What might cause cylinders 3 & 4 to quickly (several miles) carbon foul, while 1,2,5 & 6 appear with normal deposits. The engine has a rough idle; does not miss on heavy acceleration.

[Jim L.]

Re: 1954 Cylinders 3 & 4 carbon fouled

I'd look at the middle carburetor, checking for improper float level and/or worn jet and metering rod.

Jim

[David W.]

Re: 1954 Cylinders 3 & 4 carbon fouled

Thanks, Jim. I did just that...I set the float to 9/16" and installed a new needle with Viton tip, don't have a new metering rod or main jet. Know of any place they can be found??? Drove it about 10 miles on country roads, and there doesn't appear to be any fuel leaking at the air horn when I shut it off. Soon as it cools off, I'll check the # 3 & 4 plugs. Dave

[David W.]

Re: 1954 Cylinders 3 & 4 carbon fouled

Just pulled # 3 & # 4 Plugs...both carbon fouled. Wonder what is going on?

[Jim L.]

Re: 1954 Cylinders 3 & 4 carbon fouled

David,

I don't know a source of replacement jets and metering rods. When the carbs on my '54 began running rich due to wear, I was lucky enough to have a spare set of carbs with usable rods and jets.

Been thinking about your problem some more..... something else you might explore is whether the choke plate on that center carburetor is fully open. If not, a rich condition for #3 and #4 will result.

Jim

[Jim L.]

Re: 1954 Cylinders 3 & 4 carbon fouled

Just pulled # 3 & # 4 Plugs...both carbon fouled. Wonder what is going on?

Do you have a set of pin gages with which you can check the bores of all three jets? As little as .001 wear will significantly enrichen the air/fuel mixture.

Similarly do you have calipers or micrometers with which you can check the diameter of the metering rod? Same comment..... it takes very little wear to alter air/fuel.

Jim

[Ken A.]

Re: 1954 Cylinders 3 & 4 carbon fouled

Sounds like 2 plugs are not firing. Check ignition system thoroughly. (wires, cap, rotor & switch plugs with 2 other cylinders.)

[David W.]

Re: 1954 Cylinders 3 & 4 carbon fouled

It does sound like they aren't firing. I have an oscilloscope and will check to see. All new wires and cap.

[David W.]

Re: 1954 Cylinders 3 & 4 carbon fouled

I guess I better check the size of the metering jets and the metering rods. They're old and could be worn enough to cause the problem. Thanks. Dave

[Jim T.]

Re: 1954 Cylinders 3 & 4 carbon fouled

If you have some of the old wires, try them to see if it fires OK.

[David W.]

Re: 1954 Cylinders 3 & 4 carbon fouled

A good idea, but I don't have the old wires I did check each wire with an ohmmeter, and each one has continuity. I'll check the cap and rotor next, and then check the system with an oscilloscope for available voltage and required voltage

[Troy P.]

Re: 1954 Cylinders 3 & 4 carbon fouled

Searching the web for Carter YH carb info last year I found a guy that makes the metering rods. He's not a Corvette guy but deals with all the other vehicles and boats that used the YH carb. I don't have his info handy but suspect you can duplicate my search.

[David W.]

Re: 1954 Cylinders 3 & 4 carbon fouled

Hi, Troy...good info. I'll look for him. Thanks

[Jim L.]

Re: 1954 Cylinders 3 & 4 carbon fouled

I found this when I searched for "carter YH metering rod":

http://www.blackhawkengr.com/Black%20Hawk%20Engineering%20-%20Custom.html

Looks really interesting.

Jim

[David W.]

Re: 1954 Cylinders 3 & 4 carbon fouled

Hi, Jim...Yes, I was just looking at Blackhawk's web page. The tapered metering rods seem to make sense. I'll contact them.