Part-throttle lean condition, 53 R110, SD220, Carter YF


IHC in the early to mid-fifties.

Golden Jubilee
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Post Mon Oct 21, 2019 1:40 pm

Re: Part-throttle lean condition, 53 R110, SD220, Carter YF

I hate that about modern gas. I just fired up my Caddy for the first time in about a month and I had to prime it first because the carb was dry.
52 L110
61 C112
68 Cadillac Coupe DeVille
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Yard Art
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Post Thu Oct 24, 2019 11:49 am

Re: Part-throttle lean condition, 53 R110, SD220, Carter YF

It would be useful to know the carburetor identification number of the carburetor you are using. Would also be useful to know the results of a compression test.

Changing from a 0.104 to 0.107 main metering jet is HUGE.

Lifting the metering rod a 1/16 of an inch is also HUGE.

Knowing the carburetor number would allow determining if: (A) the carb is correct for the engine (too large a venturi will cause exactly the symptoms you describe), (B) the correct calibrations for the carburetor, and (C) the correct adjustment of the metering rod.

For the record, just checked my database, and have no record of any of the 300 or so different type YF carbs that have a 0.060/0.040 metering rod??? Some other Carter carburetors WCD, WGD, WCFB, and YH used such a rod. All are different length than the YF rods.

Normally I would concur with those suggesting ignition issues for your symptoms; but the posts you have made about the carb make me wonder if you have the wrong carb.

Jon.
Good carburetion is fuelish hot air!

If you truly believe one size fits all, try walking a mile in your spouse's shoes!

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Post Fri Oct 25, 2019 3:49 am

Re: Part-throttle lean condition, 53 R110, SD220, Carter YF

Carb. # is 735SA

If it is not raining on Saturday, I'll try to run a compression test.

Thanks,

Bill
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Yard Art
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Post Fri Oct 25, 2019 6:34 am

Re: Part-throttle lean condition, 53 R110, SD220, Carter YF

Standard rod in the 735s was a three step rod: 0.0725 x 0.06025 x 0.040

Jon.
Good carburetion is fuelish hot air!

If you truly believe one size fits all, try walking a mile in your spouse's shoes!

Owner, The Carburetor Shop in Missouri

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Post Fri Oct 25, 2019 8:25 pm

Re: Part-throttle lean condition, 53 R110, SD220, Carter YF

Is there something that could added to gas to damper the evaporation process so it would last longer in carb bowl?

Golden Jubilee
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Post Fri Oct 25, 2019 8:37 pm

Re: Part-throttle lean condition, 53 R110, SD220, Carter YF

My area has non- ethanol hi test gasoline, besides being easier on rubber components in the fuel system it seems to be better when it comes to the evaporation problem. My truck recently sat for two and a half weeks without being started. When it came time to use it again I pulled the choke, pumped the pedal twice and it popped right off. For the Winter and longer periods of non use I add fuel stabilizer but I really don't know how that effects the evaporation rate.
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Post Sat Oct 26, 2019 2:35 pm

Re: Part-throttle lean condition, 53 R110, SD220, Carter YF

Compression Test results:

1 - 125
2 - 135
3 - 130
4 - 130
5 - 135
6 - 119 (135 after oil added to cylinder)

#6 is low, I will need to investigate when I have more time.

The metering rod could very well be a three-step. The first two diameters match your numbers. No more time today to investigate.

Thanks,

Bill

*Edit:

I should add that I did the test as soon as the temp. gauge entered the normal range. The engine was not good-and-hot as it would be after driving. The last two times that I had the truck out since making the metering changes, it has run reasonably well. The lean spot is in a narrow range and is short-lived. Normally I would not mess with it further except I know that the carb. is set much richer than it should be.

Still idles much better when the ambient temperatures are cooler like today. I don't have trouble starting the truck if it has been sitting for a couple of weeks.

Golden Jubilee
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Post Mon Oct 28, 2019 2:08 pm

Re: Part-throttle lean condition, 53 R110, SD220, Carter YF

I can sometimes get real gas locally but most of the time I have to drive about half an hour to go get it. I prefer to run 100% gasoline in all of my older vehicles when I can, they just run so much better with it than they do with an ethanol blend.
52 L110
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Post Mon Oct 28, 2019 7:07 pm

Re: Part-throttle lean condition, 53 R110, SD220, Carter YF

TNbogy wrote:Is there something that could added to gas to damper the evaporation process so it would last longer in carb bowl?

It is called an electric priming pump.
The fuels of 2019 do evaporate much faster than the gasoline of 50 - 70 years ago. I am old enough to remember fuel evaporating from the carburetor bowls in the 1950s and 1960s.
My brother and I drove a 1939 Ford Coupe to high school. The fuel would evaporate over the school day. Mister Pagnotta, the automotive shop teacher, suggested we install an electric fuel pump on a momentary on switch. This removed the difficult cold start on an empty carburetor. The old Ford Flathead often suffered vapor-lock because the mechanical fuel pump is at the back of the engine. When we felt the engine start to stumble, we would momentarily flip the switch for the electric pump. The pump would fill the float bowl and the engine would start in a turn or two. Problem solved.
Gasoline is designed to evaporate. It has been this way for more than one hundred years. Fuel systems and gasoline have changed.. Old original trucks fuel systems have not changed and have become less compatible with modern fuel. You cannot change the fuel that is available, so, make your truck compatible.
OK CB89, lets see your critic.
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