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Joined: Oct 2010
Posts: 221
Backyard Mechanic
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OP
Backyard Mechanic
Joined: Oct 2010
Posts: 221 |
I just popped the head off my 26, and the amount of carbon build up was unreal, caked on the pistons. It has acted as though it was to rich, now I know it is. The spark plugs were powder black as well. The carb has been rebuilt, needle valve seats fine, float is the right height. So, what is the right jet to be running it a a mile high (Denver)? Are there other things I should be looking at?
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Joined: Dec 2001
Posts: 10,379 Likes: 1
Technical Advisor ChatMaster - 10,000
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Technical Advisor ChatMaster - 10,000
Joined: Dec 2001
Posts: 10,379 Likes: 1 |
I think you are on the right tract in that your mixture is too rich. Your carb-man will be the one to help.  
RAY Chevradioman http://www.vccacolumbiariverregion.org/1925 Superior K Roadster 1928 Convertible, Sport, Cabriolet 1933 Eagle, Coupe 1941 Master Deluxe 5-Passenger Coupe 1950 Styleline Deluxe 4-Door Sedan 1950 Styleline Deluxe Convertible 2002 Pontiac, Montana, Passenger Van 2014 Impala, 4-Door Sedan, White Diamond, LTZ 2017 Silverado, Double Cab, Z71, 4X4, White, Standard Bed, LTZ If you need a shoulder to cry on, pull off to the side of the road. Death is the number 1 killer in the world.
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Joined: Oct 2010
Posts: 221
Backyard Mechanic
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OP
Backyard Mechanic
Joined: Oct 2010
Posts: 221 |
Thanks Ray, I remember a post regarding a top-notch carb guy, somewhere in the Midwest (US). Do you have any recommendations?
PS, i post using an iPad, no spell-check and I am all thumbs. Apologies for my rough postings.
Last edited by 3rdowner; 05/06/12 08:36 PM.
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Joined: Nov 2001
Posts: 19,758 Likes: 64
ChatMaster - 15,000
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ChatMaster - 15,000
Joined: Nov 2001
Posts: 19,758 Likes: 64 |
You have a few choices. There is a dual adjustment RX-0 that permits changing the main jet mixture. I have never run one. Took one to New Mexico on VCCA tour for friend to use on his '26 Roadster but his standard RX-0 ran so well he didn't want to change.
There are also leaner main jets that were available for the RX-0 and other Carter carbs for that matter.
It may be that non original parts were put into your carburetor resulting in over fueling.
All the above assumes that you are running a Carter RX-0 which was originally installed in 1926. If running a replacement then it would be necessary to determine what it was.
How Sweet the roar of a Chevy four!
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Joined: Oct 2010
Posts: 221
Backyard Mechanic
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OP
Backyard Mechanic
Joined: Oct 2010
Posts: 221 |
Are there markings on the jet to indicate size? If so, what is the standard size from the factory? I have the carb out of the car, so I will check for markings. Also, does anyone know the actual jet dimension? I can check the orifice with a pin gauge to see if the years have open-up the jet. This can happen over the years.
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Joined: Dec 2001
Posts: 845
ChatMaster - 750
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ChatMaster - 750
Joined: Dec 2001
Posts: 845 |
The number stamped on the face of the jet is the orfice hole size in "number" drill numbers. The greater the number, the smaller the orfice size. Assuming you have a Carter Carburetor, the chart I have says 1925-6-7 carb multiple jet nozzel has #67 on the vertical jet and #70 on the diagonal jet.
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Joined: Oct 2010
Posts: 221
Backyard Mechanic
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OP
Backyard Mechanic
Joined: Oct 2010
Posts: 221 |
Thanks Oldie! Once again, the VCCA comes through. Now, can you'all come over to my place and help my find a leak in my roof? Just replaced the roof last year and again, it leaks.
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Joined: Oct 2004
Posts: 535
Oil Can Mechanic
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Oil Can Mechanic
Joined: Oct 2004
Posts: 535 |
Let us know how you come out on this. There are some additional resources in the Denver area that I can refer you to.
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Joined: May 2002
Posts: 1,213 Likes: 1
ChatMaster - 1,000
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ChatMaster - 1,000
Joined: May 2002
Posts: 1,213 Likes: 1 |
From a 1927 General Motors Australia booklet about carburettor adjustments for 1927 models,a change was made to the main jet.Instead of the original 67-70,a replacement 67-71 main jet was offered.The diameter of the vertical jet hole is 0.029",and the diameter of the diagonal jet hole is 0.026".According to the book,this new main jet was supposed to give better all round running & economy.
CJP'S 29
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Joined: Mar 2011
Posts: 320
Backyard Mechanic
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Backyard Mechanic
Joined: Mar 2011
Posts: 320 |
You PAY THE AIR FAIR I'LL DO THE ROOF HAH HAH, RAY
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Joined: Oct 2010
Posts: 221
Backyard Mechanic
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OP
Backyard Mechanic
Joined: Oct 2010
Posts: 221 |
Thanks for all the advice, and I will let you know how it goes. I got carried away and the entire engine is apart. Honing the cylinders and rebuilt the head next week. I got an great deal on a 26 head on eBay, advertised as a 28, but upon viewing the pics, I noticed it had one exhaust port. I rolled the dice and ended up with a great casting. New valves, guide liners, springs and a fresh grind, flat within 0.001, can't wait to fire it up!
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Joined: Jan 2002
Posts: 809
ChatMaster - 750
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ChatMaster - 750
Joined: Jan 2002
Posts: 809 |
Great find these days, if it's not cracked you're one lucky bloke.
Chris
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Joined: Feb 2011
Posts: 277
Backyard Mechanic
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Backyard Mechanic
Joined: Feb 2011
Posts: 277 |
who sells jets and needle valves for the RX-O. and the. RAKX-O any in Denver area?
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Joined: Nov 2001
Posts: 29,863
Tech Advisor ChatMaster - 25,000
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Tech Advisor ChatMaster - 25,000
Joined: Nov 2001
Posts: 29,863 |
The Mangy Old Mutt
"If It's Not Junk.....It's Not Treasure!"
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Joined: Aug 2003
Posts: 720
Oil Can Mechanic
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Oil Can Mechanic
Joined: Aug 2003
Posts: 720 |
did you pressure check the head before you put it on ? i checked six before i found a good one the six make good boat anchors . it is easer to check before than after it runs hot and ruins the good stuff you just put in hope this helps
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