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Old 11-10-2013, 06:22 AM   #31
stoveboltgeek
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I can see his point about teflon bushings. I've seen graphite impregnated brass ones as well for sale. But, I don't repair carburetors for a living, so I'm not going to argue with him.

I'm still trying to figure out what you mean by "CO2 readings were 8 for both". If you mean he connected your carburetor to a carburetor airflow testing machine, and measured the air/fuel ratio on primary and secondary is 8 to 1, then yes - you have a huge problem.

Since the "ideal" air/fuel ratio is 14.7 to 1, an 8 to 1 ratio would explain your horrible fuel mileage. 8 to 1 is more like what you'd use with the choke full on to start the engine. Incorrect or drilled-out jets are likely culprits, as are incorrect metering rods or metering rod springs.

At this point, I'm going to step back. PM me if you need additional specs on the original components.
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Old 11-10-2013, 07:03 AM   #32
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The carb guy hooked up some sort of portable tester – a hose to one of the exhaust pipes and then the box gave readings. It read what I understood to be CO (carbon monoxide) as an indication of richness. It was reading 8% off both primary and secondaries, where it should have been 1.5% off the secondaries and something closer to 3% off the idle. So that is where the scope to improve on the economy lies.

Like I said, he's going to fix the throttle shaft first and then work on the jetting. He said he would start with the standard sizes first and then tweak (not twerk) from there.

Btw, had been invited to display my car at one of the annual vintage and historic track race meets today. Was heaps of fun and was in a great vantage point for the races.
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Old 11-10-2013, 09:30 AM   #33
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Okay - that is correct.

The tester used probably tests for CO and HC. CO is carbon monoxide - fuel that couldn't burn completely because there wasn't enough air. HC is hydrocarbons - fuel that didn't even attempt to burn, usually because of faulty ignition or burned exhaust valve.

No question it's running very rich.

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Old 11-10-2013, 12:46 PM   #34
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Sorry to jump in but what are the metering rod numbers and jets for a stock 55 V8 car and thanks
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Old 11-10-2013, 02:36 PM   #35
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Quote:
Originally Posted by 55copper View Post
Sorry to jump in but what are the metering rod numbers and jets for a stock 55 V8 car and thanks
120-155 primary jet,
120-187 secondary jet,
75-1161 metering rod,
11-263S low speed jet.
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Old 11-10-2013, 02:49 PM   #36
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Quote:
Originally Posted by stoveboltgeek View Post
120-155 primary jet,
120-187 secondary jet,
75-1161 metering rod,
11-263S low speed jet.
Thanks
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Old 11-10-2013, 10:31 PM   #37
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I would inspect the shaft for wear. It seems to be the real wear part of the carb, not the base casting. Most of the WCFBs i've taken apart have worn through the chrome plating on the shaft. I know Chuck Smith has shafts for the 2x4 carbs but I don't know if he has them for the single quad. The angle of the secondary butterflies may be different since the single uses a 166 and the 2x4 uses a 193.
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Old 11-18-2013, 02:47 AM   #38
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Ok, the car (and carb) spent a few hours with the man in Thornbury today. Here's what he found:

The throttle shaft, previously thought to be loose, was ok. It was the linkage from it that was loose, so that was re-peened.

The main problem was coming from one of the metering rids, which had become dislodged.

Jets were fine, as it turned out.

Fuel pressure was good at 5.2 psi.

Idles were re-set and CO read at 1.6%. Better than the 8% previously.

But he did find that the engine was running 1.7% richer with the air filter fitted. So it looks like my configuration of a 3" paper filter within the original 4-barrel cleaner is actually restricting air flow. Maybe a 2" filter is ok, and the additional flow over the top of the thing (unfiltered) will be ok?

Anyway, I'll fill the tank in the morning and take another reading of fuel (un)economy in a week's time and see if it improves from 8.9 miles/gallon.

Thanks everyone for the comments and assistance.
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Old 11-18-2013, 09:59 AM   #39
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John, that is good to hear that you found the reason for your carb problems. What is interesting is the 3 inch filter causing air flow issues. Could you post some pictures of your modified air filter? I would think that the shorter filter would cause more restriction. Let us know what you find when changing to the shorter filter.
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Old 11-18-2013, 03:29 PM   #40
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What I mean is, I have the original 4-barrel air cleaner, removed the oil bath filter and replaced it with a new 3" high paper filter. Being this high, pretty much a of the air flow is coming through the snout and through the paper, and not over the top. I figured this would provide the cleanest air. But it turns out it is also causing restriction. If I put in a 2" filter it will increase air flow over the top, but it won't be as well filtered.

Will take a pic this morning and post.

I thought it was a pretty good conversion, but obviously I need to work on it some more. Possibly another filter, or perforate existing a little.
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