54 carbs/rich

[Brad H.]

Hi. I have noticed my exhaust has alway's been black, (right side) was doing some repaint on shielding etc. so decided to check plug's.... they are also black.... I did only check them after running in shop for a few minute's.... car run's great though but crank's awhile before start.... is there a quick way to adjust carb's to lean out and not have to go through the whole procedure of adjusting everything by the book? Have not done this myself and did not want to make some wrong adjustment's. Thank you, Brad.

[Jim L.]

Re: 54 carbs/rich

Brad,

Before you adjust anything, check the metering rods and metering jets for wear. As little as 001 wear will significantly affect the air/fuel ratio.

If they are worn, and it's very likely that they are, you'll want to replace them. When you replace the metering rod, throw away the little spring at the top of the metering rod which pushes it against the side of the jet. That little spring is what caused the jet and rod to wear in the first place.

Jim

[Brad H.]

Re: 54 carbs/rich

Jim, am a novice at that, what would I look for for wear? Seem's that it would be easier to turn some screw's and check the plug's to see the difference but which one's? why take thing's apart if I don't need to? Thank you.

[Jim L.]

Re: 54 carbs/rich

Brad,

It isn't possible to compensate for worn jets and rods by turning screws. The parts have to be replaced if they are worn, and most of them are.

To gain access to the rods and jets, you need to remove the fuel bowl lids. Inside the bowl, the rods are suspended from a hanger and drop down into the jets, which unscrew.

You can inspect both parts with a magnifying glass after you remove them. On the side of the rod, look for a shiny streak in the vicinity of the lean/rich step Typically, you'll see this shiny streak has worn to become a flat area. Looking at the hole drilled in the jet, with a sharp eye you might be able to perceive that it isn't quite round due to wear.

Any detectable wear means the parts need to be replaced, preferably with new parts if you can find them. (I don't know if any reproductions are available; when I did my YH carbs, I had a spare set from which I robbed a good set of jets and rods.)

Even if your rods and jets are not worn (highly unlikely), I strongly encourage you to throw away the little springs at the tops of the rods. They aren't necessary and they are what cause these parts to wear. How unnecessary are they? I threw mine away 16 years ago and have driven my '54 from one side of this country to the other without them.

Jim

[Brad H.]

Re: 54 carbs/rich

Jim... aren't they making these kit's in the corvair area? Thank you for the info. Brad.

[Brad H.]

Re: 54 carbs/rich

Hi Jim, back again. I took the metering rod out and the jet also. Jet hole is nice and round. My metering rod has no spring above it, only the little keeper holding rod to arm, Diaphram (I think it is) that carrier's arm has spring on top. Metering rod has the flat spot on both sides that start's at 9/16 and continues up a strong 1/4. the rod is smaller diameter up to a little over an inch from bottom of rod to that point then flare's to a strong 1/16 from there up. Just under the flat spot there is a little shine but rod look's smooth and round. This is on back carb at firewall. What do you think? Brad.

[Brad H.]

Re: 54 carbs/rich

Hi Jim, did that last message come through? if so what do you think, or any body else who might have an idea. Thank you.

[Jim L.]

Re: 54 carbs/rich

Hi Jim, back again. I took the metering rod out and the jet also. Jet hole is nice and round. My metering rod has no spring above it, only the little keeper holding rod to arm, Diaphram (I think it is) that carrier's arm has spring on top. Metering rod has the flat spot on both sides that start's at 9/16 and continues up a strong 1/4. the rod is smaller diameter up to a little over an inch from bottom of rod to that point then flare's to a strong 1/16 from there up. Just under the flat spot there is a little shine but rod look's smooth and round. This is on back carb at firewall. What do you think? Brad.

I think you've found the cause of the rich condition, Brad. The metering rod should be completely round in the area where it enters the jet. Are all three rods equally worn (more or less)?

Regarding Corvair kits..... I assume you mean rebuild kits, true? In general rebuild kits do not include replacement metering devices. Too, I'd be surprised if the Corvair YH carbs were jetted the same as the Corvette YH carbs. In fact, I'd bet they aren't so you couldn't use Corvair rods and jets.

[Brad H.]

Re: 54 carbs/rich

Hi Jim...I took the lid's off the front and mid carb's and found they had the spring's on them. the front and rear m. rod's both have a (appear's) machined flat spot about a strong 1/4 long opposing each other starting at 9/16 above bottom of rod well above where round spot travels up and down in jet, both appear very round with each jet very round. The middle carb M. rod has no machined flat spot like the other two but does have a worn spot and a little flat where it travel's in jet, The jet hole is round but is bigger than the front and rear carb jet's therefore making the fit somewhat sloppy Hmmm. Am wondering if I only need the 1 metering rod and jet or should try and find all three? Have you or anyone else delt with the carb doctor out of Canada. I tried their no. but must have closed for the day. Anyone else have or has a source to get only these part's? Thank's, Brad.

[Jim L.]

Re: 54 carbs/rich

Brad,

I think I'm following your descriptions, but clear, sharp pictures would be a big help. Can you make and post them?

The way I'm reading it, someone has put a larger jet in the middle carburetor. That and the wear flat you might be seeing would make the center two cylinders run rich.

If you have micrometers, I encourage you to measure the lean and rich steps of all three rods to be sure they are the proper size. Measure across a diameter where there is no wear and across the wear diameter, noting the difference. If you can measure .001 or more, the rods are worn and I recommend replacing them.

Bonus job: If you have a set of pin gauges, check the diameters of the jets and compare them to what should be there. To check for jet wear, insert the largest pin gauge which will pass through the jet and hold it up to the light. You are looking for an out of round condition which would be indicated by more light coming through at one point around the circumference of the jet hole.

I don't have any experience with any carb rebuilder. I do my own work. Maybe someone else can chime in.

Jim

[Brad H.]

Re: 54 carbs/rich

Jim, part's that small I can't get a close pic to show. My front and rear jet's are the same size at about 5/64 and round, the center jet is bigger than that and sloppy with the rod in it. Thank you for all the info. Brad.

[Jim L.]

Re: 54 carbs/rich

Brad,

Here is a link to a page which shows the original sizes of the jets and metering rods:

http://www.blackhawkengr.com/Black%20Hawk%20Engineering%20-%20Replacement%20Metering%20Rods.html

Notice two things:

1. Corvair dimensions are different; you can't use rods/jets from a Corvair YH
2. The difference in metering rod diameters between lean and rich step is only .003. It doesn't take much imagination to see how even 001 wear can significantly affect air/fuel metering.

In any event, Blackhawk seems to be able to make replacement parts which will solve the problem mis-matched parts in your YH carbs. I've never dealt with Blackhawk so I have no opinion about the quality of their products. IOW: Caveat Emptor

Good luck,
Jim

[Brad H.]

Re: 54 carbs/rich

Thank's again Jim, I will talk with them about their product's. Brad.

[Jim L.]

Re: 54 carbs/rich

Brad, how about posting a follow-up after you've spoken to Blackhawk and have the rich condition corrected.

Jim

[Brad H.]

Re: 54 carbs/rich

Jim... I have ordered a three carb metering rod/jet for the 54 car from Blackhawk engineering.(Colorado)As per Chuck, the rod and jet are designed to also work properly with today's gasoline. I will do all three carb's the same. Hopefully will need no adjustment's... will know when I fire it up. Talk later to you all. Brad.