Dick R

Weber 32/36 jetting - c.d.eisel's vs. Carl's prescriptions

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I'm replacing my single-barrel Solex with at 32/36 Weber on my 71 stock 02.  In reviewing lots of info on this site for jetting recommendations, I have reached a quandy trying to choose between two highly regarded experts on this topic:  c.d.eisel and Carl Nelson.  They are surprisingly different prescriptions.  Does anyone have an opinion based on trying both of them?  Here's a chart of each of their prescriptions (which I hope I have listed correctly), plus what the carb (used) came with.  No doubt, they both work.  Just looking to get swayed one way or the other. 

 

 

image.png.eb8c21c8de25fe8afb9c42663afb0833.png

 

       
       
       
       
       
       
       
       
       
       
       
       
       

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Since you already have the f-50 emulsion tubes, I'd run c.d.'s jetting.

 

(which is what I have now)

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I don't exactly remember where I usually end up, but I DO remember CD's ran me pretty rich.  

Which isn't the worst thing in the world, but it's best not to stay there forever.

 

I learned some while back that my jetting today is probably not perfect for your car today,

and that mine might be wrong for me tomorrow.  

 

So it's an ongoing project to figure out what works best for you as you figure out what 

compromises work best when.

 

Wideband oxygen meters just keep getting cheaper...

 

t

 

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After lots of trying to tune self with my afr gauge, eventually I have up and threw in CD perscription and the thing worked pretty damn well. Little rich but solid. 

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Did you plug the secondary enrichment hole?

If so, did that make a noticeable difference on the afr gauge?

 

I recently plugged that on mine, after running with it open for five years, or so.

Plugged it once, but the plug fell out, or something.

 

I am not sharp enough to notice a difference with/without.

Is the gauge?

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Dick

IMHO CD's prescription is a little fat for a stock motor especially on the secondary side. but then the old saying is "a fat motor is a happy motor" up to a point

I think I would just start with the original jets and airs and emulsion tubes  Then adjust after running it a little to solve any and bogs or stumbles.

For my slightly modified motor with 9.5:1 pistons, 284 cam and shorty headers I'm happy with the following:

P Idle 65, P Main 150, P Air Corrector 170

S Idle 55, S Main 145, S Air Corrector 160

Emulsion Tubes are F-50 

This is probably a little rich for a stock motor but you could reduce the jets one setting at a time to see how your car performs

My 2 cents

 

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image.png.eb8c21c8de25fe8afb9c42663afb08

 

I seem to recall that your question has been asked before, but I have not bothered to search for it.  It has been said many times that the so-called "C.D. prescription" is a base line approach which works well as a starting point.

As others have indicated, there are numerous variables when it comes to jetting.  This includes your engine's mechanical condition, compression, camshaft and valve train differences, ignition timing and most importantly - anticipated operational demands for your engine.  The engine can be tuned for better low end torque favored with an automatic transmission, or higher rpm horsepower production that tends to be favored with a manual transmission.  All of this can be impacted by the final axle ratio and your driving style, be it highway or heavy stop and go traffic.  Naturally, altitude and ambient temperatures can also influence jetting choices.

 

I agree with others that the CD formula results in a richer mixture when compared to the other two options.  The CN recipe http://www.bayarea02.com/features/carburetor/carl_nel.html  is leaner and probably better suited for the smaller displacement 1600 cc engine or a very tight/fresh engine.  CN also discusses using a cannon manifold but doesn't seem to distinguish any jetting differences between that manifold and the stock two barrel version.   With the possible exception of the idle jet size (Prefer 60)  and the emulsion tube, I have had overall better results with your Goldilocks "original" settings.  But I have had different results with high compression pistons and different heads (121 versus E12) and bigger valves.  Even with two identically prepared long blocks, optimum mixture production can still necessitate different carburetor jetting.  Bottom line:  your mileage may vary.  It really is not that hard to experiment with all three or more recommended settings.

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23 hours ago, '76mintgrun'02 said:

Did you plug the secondary enrichment hole?

If so, did that make a noticeable difference on the afr gauge?

 

I recently plugged that on mine, after running with it open for five years, or so.

Plugged it once, but the plug fell out, or something.

 

I am not sharp enough to notice a difference with/without.

Is the gauge?

I did plug mine but I didn't do a before and after.

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Thanks to everyone who weighed in on this topic.  Seems like CD's prescription has the most history and it's pretty positive.  I had my jet order ready to go with one more keystroke, but then I thought that since the as received jetting isn't so different,  I might as well just start with those and go from there.  Pretty easy to feel flat spots and hesitation as well as reading the plugs. 

 

I expected to have it running by now, but there's always more stuff that pops up when you make any non-stock change (choke cable, throttle rod, air cleaner, hood clearance, etc.).  I'm getting all that worked out but haven't yet connected the fuel line to attempt a start. 

 

As usual, good advice from FAQ.  Thanks. 

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Get a wideband o2 sensor, or you will go crazy trying to figure things out. 

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11 minutes ago, Dudeland said:

Get a wideband o2 sensor, so you can go crazy trying to figure things out.

 

( I fixed that for you, Dude ; )

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Paradoxically, both of the above posts are correct...

 

t

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I would agree, you get kind of obsessed with making sure you are in the green.

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anyone know where CD and Carl live?

 

Wondering about elevation playing into their jetting recipes.

Edited by joebarthlow

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3 minutes ago, joebarthlow said:

Wondering about elevation playing into their recipes.

 

Adjustment for 5000 feet:
  1. Reduce baking powder: for each teaspoon, decrease 1/8 to 1/4 teaspoon.
  2. Reduce sugar: for each cup, decrease 0 to 2 tablespoons.
  3. Increase liquid: for each cup, add 2 to 4 tablespoons.
  4. Increase oven temperature by 25 degrees F.
  • Haha 1

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