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 Post subject: Solex Issue
PostPosted: Mon Mar 12, 2018 3:25 pm 
356 Fan

Joined: Sun Feb 19, 2017 2:24 pm
Posts: 41
Location: San Jose California
Hey guys,
My engine is a 1966 912 in a 1963 cabriolet. I bought a nice pair of Solex P40-11 carbs for it. I had them re-bored for a 41 mm throttle plate. Replaced the shafts, bushings, throttle pump arm assemblies and the 4 jets in the top. I then installed rebuild kits. The other jets look to be good. Put them on the car and it was difficult to start. Finally got it running and adjusted air mixtures, etc as best I could. The issue is that number 2 cylinder is not firing. I have replaced the plugs, wires, distributor cap and rotor. After some research I sprayed a bit of carb cleaner in the throat next to the plug that is possibly bad and the engine revs immediately go up and is running much better. Next I pulled the plug wire off and put in a new plug and laid it on the exhaust. (Tins are removed)...
Started the engine and checked and the plug is firing. Turned off the engine and got in there with a light to check the “squirters” and there’s a good strong stream. Then I removed the air jets, cleaned them and reinstalled them in reverse. The issue still remains. I admit my knowledge is somewhat limited but it seems to me there must be some blockage in the carb. I’m about to take the carb off and go through it again but my question is, assuming I’m on the right track, where specifically would the problem likely be? Thanks for any help!


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 Post subject: Re: Solex Issue
PostPosted: Mon Mar 12, 2018 4:02 pm 
356 Fan
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Joined: Wed Mar 26, 2008 3:02 pm
Posts: 844
Check the numbers on the jets it is possible to install the wrong jet in the location there is another jet which will fit but is wrong.


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 Post subject: Re: Solex Issue
PostPosted: Mon Mar 12, 2018 5:05 pm 
356 Fan

Joined: Fri Dec 03, 2010 7:42 am
Posts: 289
Use a paint brush bristle and determine whether you can push it through the orifice in the idle jet for #2. Idle jets work as a filter for gasoline.


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 Post subject: Re: Solex Issue
PostPosted: Mon Mar 12, 2018 6:00 pm 
356 Fan

Joined: Sun Feb 19, 2017 2:24 pm
Posts: 41
Location: San Jose California
Thanks guys, just checked on both those suggestions....since my earlier post, I took off the carbs and reversed them on the engine. Sure enough, the problem followed the carb and number 2 was firing but not number three. I disassembled the bad one, blew air through all the ports, orifices, etc. and checked the jets for blockage. I put it back on and started the engine. Strangely it seems better now but when I pull the plug wire off at the distributor, no change in Idle and the Air mixture screws have no effect. Very puzzling.


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 Post subject: Re: Solex Issue
PostPosted: Mon Mar 12, 2018 8:59 pm 
356 Fan
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Joined: Sun Apr 20, 2008 12:40 pm
Posts: 699
Location: Shoreline, Washington, USA
Tag: Ex 356 Mechanic
Even with a new throttle shaft, the two butterflies may not be aligned. Set the idle to about 1,000 RPM. If you have a Unisyn or other gadget check that all 4 barrels have the same airflow. No Unisyn? Use a foot of vacuum or fuel hose, when the idle is steady (no throttle action while you are listening), put one end of the hose in your ear and the other end to each of the barrels. You listen for noise volume and the hose has to be placed in the same location on each barrel. You may find that barrel has less air flow.

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 Post subject: Re: Solex Issue
PostPosted: Mon Mar 12, 2018 9:03 pm 
356 Fan

Joined: Sun Apr 20, 2008 12:54 am
Posts: 2809
Greg,

You could have the #.7 and the 180 jets swapped--the screw threads are the same; the #7 feeds the power circuit, but the 180 is the idle air.
Look @ the instruction/parts list sheet.

Dick


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 Post subject: Re: Solex Issue
PostPosted: Mon Mar 12, 2018 9:18 pm 
356 Fan

Joined: Sun Apr 20, 2008 12:54 am
Posts: 2809
BTW Greg,

Were the carb "feet" machined flat and matched to its 'neighbor' equally? If carb cleaner detected an air leak, that'll indicate out-of-flatness!
DON'T use thick carb-to-manifold-gaskets; They'll re-create warpage of the "feet", and only torque the nuts to 15 lb.ft. No sealant is used.
Also, make sure the fiber spacers are equal thickness and NO cracks

Dick


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 Post subject: Re: Solex Issue
PostPosted: Mon Mar 12, 2018 9:40 pm 
356 Fan
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Joined: Thu Dec 15, 2011 9:01 pm
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Location: Laguna Beach/Traunkirchen
Dick's assessment is quite astute. I have seen several "re-done" carbs delivered with some of those jets switched, and the difference between .7 and 1.8 is huge. Poor motor can hardly run that way, and perplexing to fix unless you're familiar with Solex. Of course this may not be your problem Greg, diagnosis via forum is always a bit hit-or-miss, but this is certainly something for all of us to check whenever getting Solex carbs back from a rebuilder.

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 Post subject: Re: Solex Issue
PostPosted: Mon Mar 12, 2018 9:49 pm 
356 Fan

Joined: Wed Nov 23, 2011 10:52 am
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Location: Cleveland, Ohio
I have been procrastinating for several months in putting my extra Solexes back together because of those jets, I don't trust that they were correct to start with. Could I have a diagram please? Even better, for both split shaft and single shaft? I have a set of each.

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 Post subject: Re: Solex Issue
PostPosted: Mon Mar 12, 2018 10:07 pm 
356 Fan
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Joined: Sat Apr 05, 2008 8:21 am
Posts: 3174
Location: Augusta,Michigan
https://porsche356registry.org/article/47 Greg has single shaft carbs. And if all else fails and you are still stumped go back to basics and start with a complete tuneup. Valve adjustment, points etc.

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1965 356C There is never enough time to do it right, but always enough time to do it over.


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 Post subject: Re: Solex Issue
PostPosted: Mon Mar 12, 2018 10:20 pm 
356 Fan

Joined: Sun Feb 19, 2017 2:24 pm
Posts: 41
Location: San Jose California
Complete tune up has been done, the valves were adjusted about 200 miles ago. I started to think maybe it was a valve issue but then after reversing the carbs on the engine, the problem went from number 2 to number 3 cylinder.


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 Post subject: Re: Solex Issue
PostPosted: Mon Mar 12, 2018 10:26 pm 
356 Fan

Joined: Sun Feb 19, 2017 2:24 pm
Posts: 41
Location: San Jose California
Butterflys are equal.
I have a synchrometer and will check the draw on each throat.
.7 and 1.8 jets are the same on both throats and #1 is firing good.
The feet were indeed machined, the gaskets are thin and they and the spacers are new.
Is it possible that from machining, one or more ports in the throat could be blocked? Could that cause the problem?


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 Post subject: Re: Solex Issue
PostPosted: Tue Mar 13, 2018 12:19 am 
356 Fan
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Joined: Tue Jul 08, 2008 11:50 am
Posts: 639
Location: Whidbey Island WA.
Look at the inside of the throat right where the throttle plate closes for blocked holes, the three tiny holes where the idle fuel comes in as the plate transition starts. Sounds like the they are not providing fuel at the low RPM to that one hole.

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 Post subject: Re: Solex Issue
PostPosted: Tue Mar 13, 2018 12:40 am 
356 Fan

Joined: Sun Feb 19, 2017 2:24 pm
Posts: 41
Location: San Jose California
John...where do those holes go to or end up? In other words, if I wanted to try to clear them from the opposite end, where would I go?


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 Post subject: Re: Solex Issue
PostPosted: Tue Mar 13, 2018 7:48 am 
356 Fan

Joined: Wed Nov 23, 2011 10:52 am
Posts: 3269
Location: Cleveland, Ohio
Blowing compressed air into the idle mixture screw hole should come out of various places including the small holes in the throttle bore.

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