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Re-jetting the Solex

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Steelyard Blues View Drop Down
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Joined: 09 Oct. 2017
Location: Reno, NV
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    Posted: 09 Jan. 2021 at 9:13pm
Like many of us, my Jeep tends to run hot. At lower speeds, she stays at 160 but any prolonged time over 40 MPH tends to bring the temperature up to 180+. After one prolonged high-speed drive towing my M416, I pulled the plugs and noticed they were absolutly clean and white. Concerned that the higher temps may be due to a lean burn, I decided to re-jet the Solex.

Standard Solex settings for the L134 are a 127.5 main jet and a 190 air correction jet. Economy setting is a 115/195.

Standard Solex settings for the F134 are a 140 main and a 160 air correction. The economy settings are the same as the standard L134, 127.5/190.

I decided to try the F head settings, 140/160. I was already running a richer 132.5/190 combination. I know the F head makes a bit more power but, since the displacement is the same, the settings cannot be too far off and are a good reference point,

The jets are easy to replace without removing the carb. All you need is a wide blade screw driver and a 12mm wrench. The main jet is on the front of the carb, facing the radiator, and next to the accelerator pump. Remove the 12mm brass jet retainer and unscrew the main jet from it. The air correction jet is in the throat of the carb. Remove the air horn extension to access it. I suggest putting some paper towels in the throat of the carb to prevent the jet or anything else falling into the carb. The jet is screwed into a tube. The tube may spin as you try to unscrew the jet. Use a pair of needle nose pliers to hold the tube and unscrew the jet. Inside the outer tube is brass emulsion tube with six small holes in it. If you have a dental pick or similar tool, you might want to remove the emulsion tube and check for obstructions.

It took me a while to figure out where to find the correct replacement jets, especially when you tell the parts guy that you are working on a 1947 Jeep. I got several responses from Solex part providers who had no idea about the M32-PBIC carb.

The main jets are from EMPI with part numbers 43-5140-7 (140 main) 43-5132-7 (132.5 main). I got these for $10 each with shipping off eBay. Supplier was Moore Parts Source, 700 Van Buren St, Unit A, Placentia, CA. eBay seller: Moorepartssource.

The air correction jets are also used by Mikuni. I also got these from eBay for $3 each plus shipping. The 160 part number is B42/56/160. I picked up a 170 and a 180 also. Supplier was www.nichecycle.com. eBay seller niche-cycle.

I have not been able to do a prolonged high-speed drive. It is January and my Jeep doesn’t have a top. I did take it on a couple mile street drive and for a few minutes in the hills where I kept her revs up in 4L. She ran very well with good power and temps at 160 the entire time. A little difficult to gauge the outcome since ambient temperature was 45 and the cold air is a bit more dense.

Upon return, I noticed my idle speed was off and the mixture was fairly rich. I’m not sure why she was set so rich, I usually have her idling pretty well. Once I leaned her back out, she idled very smooth (NOTE the main jet does not generally operate below 1,500-2,000 RPM). When I pulled a plug, I did not get a good reading because of the rich idle. The plug was black. I plan to do further tuning once the outside temperatures are warmer. Come summertime, I will be able to see if there are any affect on coolant temperature. Since Reno is at 4,500, I may have to try a 135 or 132.5 main jet with a 180 or 170 air correction jet.

For those running a Solex and do trips to higher elevations, you might want to consider bringing a set of lean or economy jets with you.

Micah

See attached:

uploads/8657/Solex_L_head_settings.pdf



1947 CJ2A, Body & Frame: 106327, Engine: J109205, Tub and Tailgate: 97077. Originally Luzon Red

1965 Johnson Furnace Company M416 #6-1577
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aboyandhisdog View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote aboyandhisdog Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan. 2021 at 5:53pm
Thanks for this, Blues - very nice write up!  I have been running the 115 main jet in my L head for years between 8500' and 12,500' and it is PERFECT.  

But I didn't know I could get an air correction jet.  I see that Niche Cycle has them in a 200 - up from the standard 190.  They don't have a 195.  What benefit or change do you think I would see going to a 200?  (I'm not really sure what the air correction jet does.)

Might just order one (ac jet) and see how it affects the running, but would love to learn more about what it does.  BTW, I really like my Solex.  Most guys don't take the time to get to know them.  There are a couple of adjustments that I have made to dial them in, but I don't have nearly the issues 'in the field' that the Carter guys do.
Tom
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark W. Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan. 2021 at 6:03pm
I think 160 degrees is not warm enough your running a cold engine which also causes problems.
Chug A Lug
1948 2A Body Customized
1949 3A W/S
1957 CJ5 Frame Modified
Late 50's 134L 9.25"clutch T90A D18 (1.25") D44/30 flanged E-Locker D25 5.38 Since 1962
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steelyard Blues Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan. 2021 at 7:11pm
Tom,
I have no complaints with the Solex. I'm in no rush to replace it since I plan to stick this Holley on there after a rebuild with cam and headers: 
This VW site has a good write up as to what the air correction jet does: 

Mark,
160 is the stock thermostat. At idle and up to about 40 MPH she will run around 160. Above 40 MPH, my Jeep runs between 160 and 180. My issue is under heavy load or prolonged drives over 40. I have a couple stretches that I regularly drive a couple miles at 50-55. This is where I see my temps spike. With the excessively clean plugs, I'm experimenting to see if I have a high speed lean condition resulting in the excessive heat. 

Micah
1947 CJ2A, Body & Frame: 106327, Engine: J109205, Tub and Tailgate: 97077. Originally Luzon Red

1965 Johnson Furnace Company M416 #6-1577
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aboyandhisdog View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote aboyandhisdog Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan. 2021 at 8:00pm
That "jets" page was a really good read.  Thanks!
Tom
1949 CJ3A

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steelyard Blues Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan. 2021 at 9:43pm
Tom,
I'm glad to hear you found this and the link useful. You never know when you throw something out there.

Micah
1947 CJ2A, Body & Frame: 106327, Engine: J109205, Tub and Tailgate: 97077. Originally Luzon Red

1965 Johnson Furnace Company M416 #6-1577
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