Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,400

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Greg Long
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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#16 Post by Greg Long » Tue Feb 11, 2020 11:42 pm

>>>What distributer is fitted to your engine-correct unit has cast iron body and will have 022 //

Yes is ends with 022

>>>356s need to warm up before idling. Mine will idle at 800 after warm up. But will not idle cold. Or if set to idle at 1200 hot then they will idle cold at 800. This is because the manifolds need to warm up. You cannot get a stable idle above 1200 because the distributor advance begins at 1200. If the idle is set above 1200 or even at 1200 the idle speed will hunt up and down as the distributer advance changes. In order to get a nice stable 800 RPM warm idle, the tune up needs to be perfect and the plugs clean and gaped. I use the hand throttle on the As and warmup at 1700 RPM. I close the hand throttle on driving off, and then it idles at 800- till next time.

I don't have a hand throttle I believe as it's a 'C'... so is it the case that to expect it to start easily cold, and be able to idle at 800 with no driver input until it's warm just not in the cards / typical? I don't want to chase something that's not really fixable. It sounds like I should add a 6V electric fuel pump with 3lbs (does anyone know what one I should get, and where/how to install?), let the carbs fill up and then do the 3 pumps of the pedal and hold it down half and just keep the starter on until it fires; and then use my gas pedal to keep it going until warm enough to hold a 800rpm idle?

>>>>>With the engine off, look down the throats of the carbs and you should see two good streams of raw gas injected downward with each full stroke of the carb arm. This raw fuel is essential for the engine to start.

Yes, good streams on each carb. But even with the gas streaming still really hard to get it to start. But once it warms up it runs beautifully.

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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#17 Post by Martin Benade » Wed Feb 12, 2020 12:04 am

It would be fine to try pumping the gas several more times. I have to pump mine a lot more than three times to get it to start, but once it’s running it runs great.

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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#18 Post by Doug McDonnell » Wed Feb 12, 2020 12:10 am

Just to be clear in where we are. Very hard to start cold. 1. does it start easily if you try to start it after only 1 or 2 hours of cool down? or 2.It is very hard to start after 1-2 hours cool down.
1965 356C There is never enough time to do it right, but always enough time to do it over.

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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#19 Post by Doug McDonnell » Wed Feb 12, 2020 12:22 am

Cheap priming pump bulb: https://porsche356registry.org/article/77 Electric pumps are frequently installed under the passengers side floor board. https://porsche356registry.org/article/78 Others install them on the right side of the diagonal member: https://www.stoddard.com/64450144106.html And newer solution by Ron LaDow of Precision Matters: https://precisionmatters.biz/auto-prime-primer-kit.php Of course you could also remove your mechanical pump and just use an electrical pump all the time, but then you would need a spare in your travel spare parts stash.
Last edited by Doug McDonnell on Wed Feb 12, 2020 12:45 am, edited 1 time in total.
1965 356C There is never enough time to do it right, but always enough time to do it over.

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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#20 Post by Greg Long » Wed Feb 12, 2020 12:39 am

>>>Just to be clear in where we are. Very hard to start cold. 1. does it start easily if you try to start it after only 1 or 2 hours of cool down? or 2.It is very hard to start after 1-2 hours cool down.

Starts right up after an 1 or so...

>>>>Cheap priming pump bulb: https://porsche356registry.org/article/77

I love this idea... anyone have a downside to this option?

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Doug McDonnell
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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#21 Post by Doug McDonnell » Wed Feb 12, 2020 12:51 am

Then I would check your fuel pump suction and pressure. If OK do a priming bulb or pump. One of the reasons that owners of cars with Solex carbs have problems starting is that the accelerator pump system is misunderstood. On Zenith carbs when the float bowl has fuel so does the accelerator pump bowl. Not so on Solex carbs like you have in your SC. The bowl for that is filled only by vacuum on the backstroke of pumping the accelerator. Once it has filled then you get gas out of your enrichment tube when you pump the gas pedal. Which explains why those with Solex carbs do a lot more pumping than those with Zenith carbs on Normal or Super engines. Weak diaphragms for the enrichment circuit can also make it harder to fill that bowl requiring more pumping.
Last edited by Doug McDonnell on Wed Feb 12, 2020 1:03 am, edited 2 times in total.
1965 356C There is never enough time to do it right, but always enough time to do it over.

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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#22 Post by Greg Scallon » Wed Feb 12, 2020 12:55 am

Greg,
I'll let the others help out with the cold starting issues. I'm sure you'll get to the bottom of it. I will, however, chime in with a comment about the priming bulb idea. I installed a bulb in my speedster about 10 years ago and absolutely love it. Super easy install, can be removed in a jiffy if needed, requires no electricity, and it forces me to open the decklid before I go out, which lets me take a glance at my engine to make sure my fan belt's looking good and I'm not blowing oil all over the place. I still may install an electric priming pump someday, but as of now, I love the bulb. Go for it.

Good luck with your car.

Regards,
-Greg
'58 Speedster
'56 VW Deluxe Microbus 

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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#23 Post by Greg Long » Wed Feb 12, 2020 1:02 am

>>>Not so on Solex carbs like you have in your SC.

I have a 356C and Zenith carbs

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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#24 Post by Doug McDonnell » Wed Feb 12, 2020 1:26 am

Better yet. somewhere someone said 95% of carb problems are electrical. If fuel pump pressure is fine check points gap and timing. check distributor advance. Last resort if all else fine: https://www.youtube.com/watch?v=70dTCwNfQoM&t=69s But I emphasize last.
1965 356C There is never enough time to do it right, but always enough time to do it over.

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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#25 Post by David Jones » Wed Feb 12, 2020 5:24 am

Go back and read 3rd post.
If I had known I would live this long I would have pushed the envelope a little harder.
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Vic Skirmants
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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#26 Post by Vic Skirmants » Wed Feb 12, 2020 8:54 am

Doug McDonnell wrote:
Wed Feb 12, 2020 12:51 am
Then I would check your fuel pump suction and pressure. If OK do a priming bulb or pump. One of the reasons that owners of cars with Solex carbs have problems starting is that the accelerator pump system is misunderstood. On Zenith carbs when the float bowl has fuel so does the accelerator pump bowl. Not so on Solex carbs like you have in your SC. The bowl for that is filled only by vacuum on the backstroke of pumping the accelerator. Once it has filled then you get gas out of your enrichment tube when you pump the gas pedal. Which explains why those with Solex carbs do a lot more pumping than those with Zenith carbs on Normal or Super engines. Weak diaphragms for the enrichment circuit can also make it harder to fill that bowl requiring more pumping.
Doug; thanks for posting that explanation. Very well stated.

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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#27 Post by Norm Miller » Wed Feb 12, 2020 10:36 am

A lot of guesses flying around.
A few things to consider before changing anything:
Dwell
Timing
Adjustment of butterflies
Basic adjustment of mixture
Adjustment of throttle rods
Accelerator pump volume or at least some

Otherwise, you are pixxing into the wind so to speak.
 

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Ken Lubke
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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#28 Post by Ken Lubke » Thu Feb 13, 2020 12:17 am

Hey Mark,

They called them he/she’s didn’t they.?

Get your car back from Dave yet???

Kenny

Greg Long
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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#29 Post by Greg Long » Thu Feb 13, 2020 9:26 pm

Hi folks... I did as many suggested and started simple... I checked the point gap and it was super small... I reset to .016" and checked the timing after making a paint mark 19/64" to the right of OT; and noted the timing was spot on. I pumped the gas pedal 4 times and turned the key: it started almost immediately. I've adjusted the carbs with a unisyn to 900 rpm. I'll see tomorrow if I can reenact the starting. In any case, I guess too small a gap can make the car really hard to start but run OK when warm? Greg

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Re: Incredibly hard cold start (50F), barely idles, then once warm it idles usually at 2,000, but sometimes drops to 1,4

#30 Post by Bruce Smith » Thu Feb 13, 2020 9:31 pm

Greg - Here's a write-up on dwell and timing from the Registry magazine a few issues back:

http://www.sparkingplugs.com/resources/ ... h+40-1.pdf

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