Solex 40 PII adjustment dilemna

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C J Murray
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Re: Solex 40 PII adjustment dilemna

#16 Post by C J Murray »

Hi Phil,
62 vs. 57.5 is a big deal. I am surprised that the car ran smoothly at a steady(no throttle movement) 2500. Also, when people ream jets larger the courteous thing to do is to file off the old size.

If you have 32mm venturis with a fairly mild engine then I am fairly certain that 122.5 mains are too large. 120 with 180 airs work but my best result has been 117.5 with 175 air jets. This has been proven in two mild 1720 cars on the dyno with exhaust gas sniffing. Camshafts and compression ratios can make settings different in a hurry though.
Cliff
'57 Speedster
'59 Sunroof
'60 Devin D Porsche Race Car
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Phil Planck
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Re: Solex 40 PII adjustment dilemna

#17 Post by Phil Planck »

Sterling
I removed all four nozzles and cleaned them out along with inspecting and cleaning the balls. Also did the same for the bottom check valve. They all squirt fine, just seems to be inconsistent from measurement to measurement from hot to cold. Right now the throttle response is good. Right carb yesterday measured .3cc and left hardly anything.

Also, per advise from 356 carb rescue I left the filler beads out, as Jim suspected they were added for some emissions reason and could cause plug ups fairly easily.

Cliff - hope to do a 3000 rpm 5 minute test run and remove a plug to see how it looks tomorrow. Jim at Carb Rescue advised the main jet sizes to try, and this was the smaller of the 2. I will report back after my "high speed" run.
Phil Planck

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Re: Solex 40 PII adjustment dilemna

#18 Post by C J Murray »

Phil-I was not 100% clear...62 is real big, 60 was too rich for me, 57.5 always works for me.

115/180(stock)works semi ok, 120/180 works better, 117.5/175 works best, 122.5/180 exhibits definite signs of richness, 125/180, is seriously rich...for me...for a mild 1720

Jim knows a lot so I have no comment on that.

NOTE- ABOVE FOR SOLID SHAFT- SORRY
Last edited by C J Murray on Fri Sep 28, 2012 5:30 pm, edited 1 time in total.
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Roland Paetsch
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Re: Solex 40 PII adjustment dilemna

#19 Post by Roland Paetsch »

Cliff,
Are your numbers for a split shaft?
Roland
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Re: Solex 40 PII adjustment dilemna

#20 Post by C J Murray »

Crap! I'm caught again. Those are solid shaft numbers. Thank you for waking me up.

I am about to use a pair of Carb Rescue split/solid conversion carbs on my 2133cc stroker. It should be dynoed in the next couple of weeks but I will be using bigger venturis so the data won't be relevant. I hope they work as well as I have been told, due to the additional transition ports.

Phil, sorry to be confusing.
Cliff
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Re: Solex 40 PII adjustment dilemna

#21 Post by Thomas Sottile »

The pump volume stated amount is only a starting point, from there you should adjust the pump a 1/4 turn at a time, both carbs and test drive until you are happy with the results.

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Re: Solex 40 PII adjustment dilemna

#22 Post by Phil Planck »

Thomas
My pump volume per se is not the issue. The issue is that when I set it cold, it seems to change when hot. This could be something I am doing wrong in my technique, or maybe it's from living to close to the 45th parallel. When I get my jet sizes sorted out I will focus more on the pump. Did not get it out today for the spark plug color test - hopefully tomorrow.
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Re: Solex 40 PII adjustment dilemna

#23 Post by Thomas Sottile »

What I'm saying is not to be so concerned with the set amount, adjust the carbs to a point of good performace. Tom

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Re: Solex 40 PII adjustment dilemna

#24 Post by Phil Planck »

Went for a low(2500 rpm) and high(3200rpm) run this morning to check spark plug "color" hopefully from idle jet(low speed) and main jet(high speed). Since air filters were off I also brought along my accel pump vial.

At 2500 for 5 minutes the plug ceramic was sooty black but the electrode was nice and clean. At 3200 for 5 minutes the plug tip was clean and the electrode was a light gray.

The accel pump output measured the same as when measured cold(finally), so it must have been my technique.

Engine ran smooth, strong and idles great. Also, cold start was much better with not as much spitting and coughing.

I think I will leave it as is for the trip to Gull Lake.

On my return run at legal speeds(3200 is about 65 mph) as I crested a hill there was a police car off to the oncoming side with his radar gun. Fortunately I was at about 2900 rpm and waved as I went by. The car about 1/2 mile behind me was not as lucky.
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Re: Solex 40 PII adjustment dilemna

#25 Post by C J Murray »

Hi Phil,
I was looking at the little spec book for the 911/912 cars. Did the split shaft carbs come with 55 idle jets and 110 idle air jets? You might want to try 55 idle jets and make sure the idle airs are still 110. Maybe Jim knows that what you are trying is better? By now you know that I do not know. The factory mains were 122.5 so you must be close there. I think the main also feeds the idle jet, unlike the solid shaft which is why the mains are larger. They also used a 40 pump jet where the solid shaft used a 50. I will be interested to see what you have when you are happy with how it runs. Please report the end result with all of the jet numbers. Enjoy your trip.
Cliff
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Re: Solex 40 PII adjustment dilemna

#26 Post by Phil Planck »

Cliff
Not sure about the air jets, but I think the 912 used same idle gas jet as 356 - 57.5. Per a recommendation from a good 356 guy I put the 356 50 pump jets in during the rebuild. I have not seen any 55 idle jets available. I do need to check all of the air jets, which I have not yet done.
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Re: Solex 40 PII adjustment dilemna

#27 Post by C J Murray »

Phil,
The little spec book has 3 sets of specs. 616/36 w/old heater, 616/36 w/new heater, and 616/39 w/emission control. The first two use 57.5 and the /39 uses 55 but with smaller idle air jets,110 vs. 180. So, are the /36 carbs solid shaft and the /39 carbs split shaft? I think that may be the case. Experts?
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Re: Solex 40 PII adjustment dilemna

#28 Post by Phil Planck »

Cliff

Gotta do some more 912 research. Just found this on Pelican site:

I have the following jets in my 69.
Main jet: 0125
Air correction: 180
Idle jet: 55
Pump jet: 40
Idle air bleed: 1.1

So it does seem some 912 Solex carbs used a smaller idle jet. Also another topic on that site a poster said the 55 idle jet made a big difference on his engine. I see Classic Speed and Parts carries various size idle jets, including 55s.

Phil
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Re: Solex 40 PII adjustment dilemna

#29 Post by Phil Planck »

It's been a while, but hopefully I now have a "final" report. I ordered 4 055 idle jets from a vendor on our web site vendor list and they never came. Could not get a phone or email repsponse. They took my money, and still have it but will not call or answer emails. So, I turned the matter over to my credit card company who will make sure I get my money back. After this delay, I noticed that Zim's posted a while back that he had some Solex jets so I called and sure enough they had 4 055s in stock(Solex brand) and they came quickly. Snowed up here last night, so I figured I better get this road test out of the way. After a warm up, I reset idle mixture screws(just a little more outward turn) and did a 6 minute 2500 rpm run and killed the engine. Pulled #2 and #4 plugs and they were no longer sooty like with the 57.5 jets. Color looked good. Car ran good, I am happy.

So, the final(I hope) config for my engine is:

Solex split shaft converted to solid
All jets S90 spec except .55 idle and 122.5 main(which may be S90 spec).
Norris 331S cam
AA big bore(cast iron cylinders)
912 heads & crank
S90 case
S90 flywheel modified for "normal" shim and front main

Thanks for all of the advice. I did use a penny to set idle mixture screws, since Ab never sent me a custom set to take to Other Coast swap meet(just kidding Ab) and I have not ordered those nice super stubby screwdrivers.

April 26, 2013 Update

Car has run crappy all spring on the idle circuit. Tried Vic's discovery of backing out idle adjustment screws 1/2 turn, but did not help. Put the 57.5 idle jets back in and that fixed the problem. Not sure what has happened since last fall. Weather has been cool(50s) during tests. I did clean the 55s but did not help. Has mix of last years gas a fresh gas, so maybe the old gas. Idled very bad with screws out 1/2 turn from "normal" so turned them in 1/4 turn which improved idle a lot.
Last edited by Phil Planck on Sun May 26, 2013 1:22 pm, edited 1 time in total.
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Re: Solex 40 PII adjustment dilemna

#30 Post by C J Murray »

Phil- Glad you made it happy. Enjoy. Cliff
'57 Speedster
'59 Sunroof
'60 Devin D Porsche Race Car
'63 Cabriolet "Norm"
'67 911 S Original Owner
'03 Ferrari 575M
'09 Smart Passion

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