Diag: Recently running again but having some running issues?

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Harold Singh
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Re: Diag: Recently running again but having some running iss

#46 Post by Harold Singh » Tue Oct 02, 2018 5:37 pm

Franny Brodigan wrote:Harold, A question: Does the engine run fine at 3K rpm with no load? Does it only falter under load?

Do you have a cut fuel line from the pump to the carb? Can you splice in a fuel pressure meter there? It can be done with the original steel line, but You'll need a double banjo bolt and fuel line connector.

If it is faltering both under load and not, see if your fuel pressure is dropping at speed. Just have an extinguisher at the ready whenever modifying fuel lines. I bought a very useful low pressure/vacuum meter for not much money and have used it quite a lot actually.

You eliminated the condenser so that is a big data point. Now you need more information.

You'll get it!

Franny
I do have braided rubber hose already sectioned in for fuel line I can splice into. No low pressure gauge right now. Any recommendations on an accurate one that is easy to install? Meaning set up for splicing into the hoses.

Here is a video yesterday of it doing cold start. See the focus on the oil temp which matched ambient temp. 1+1/2 pumps and fires just fine as usual from cold.

https://youtu.be/YL2KpG_Blzg

So, since it fires right up again, I of course drive it afterwards.

It has been revving fine, warmed a bit and then after I drive it on th road, under load it falls flat.

After I made this video I pulled the carb jets and saw a bit of crusty clear fuel where the ideal jets are located. I cleaned them all and reassembled. Number 4 seemed a bit clogged but was not blocked completely. Enough to slow it down.

Reassembled and it ran the same.

Next on the list is to pump out all the fuel, clean the filter under the tank and blow out the lines.

Thanks,
Harold
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Re: Diag: Recently running again but having some running iss

#47 Post by Thomas Sottile » Tue Oct 02, 2018 6:52 pm

I would check the thermal spacer under the fuel pump if it is too thick it will no allow full stroke of pump. This is a common mistake with rebuilt pumps installation. If you get us the width of the spacer we can compare it to others it may be too thick

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Re: Diag: Recently running again but having some running iss

#48 Post by Harold Singh » Tue Oct 02, 2018 7:22 pm

Thomas Sottile wrote:I would check the thermal spacer under the fuel pump if it is too thick it will no allow full stroke of pump. This is a common mistake with rebuilt pumps installation. If you get us the width of the spacer we can compare it to others it may be too thick
.27” no other gaskets. Compared to another C that was about 1/4” on his measurement.
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Re: Diag: Recently running again but having some running iss

#49 Post by Mervyn Hyde » Tue Oct 02, 2018 8:02 pm

Harald if this is not electrical it is fuel delivery. It sounds somewhat like fuel starvation. If you are finding sludge or impediments in the jets that is suspicious. You need to clean the carbs - after cleaning (blowing or pumping) out the fuel lines to the cars, from the tank. It may be that there is a blockage in that line. Is the petcock fully on and working? Is it set correctly? Checking with a borrowed pump is good start.
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Re: Diag: Recently running again but having some running iss

#50 Post by Harold Singh » Tue Oct 02, 2018 8:07 pm

Mervyn Hyde wrote:Harald if this is not electrical it is fuel delivery. It sounds somewhat like fuel starvation. If you are finding sludge or impediments in the jets that is suspicious. You need to clean the carbs - after cleaning (blowing or pumping) out the fuel lines to the cars, from the tank. It may be that there is a blockage in that line. Is the petcock fully on and working? Is it set correctly? Checking with a borrowed pump is good start.
When on, it seems to be pouring out of the line from the tank to the engine that runs to the back. Without much effort. I’ll pump it out and clean the filter and lines to be safe.
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Re: Diag: Recently running again but having some running iss

#51 Post by Mervyn Hyde » Wed Oct 03, 2018 11:54 pm

Good idea and that suggests at least that it is getting fuel to the carbs. Check to see if there is any debris in the fuel that was pumped out. Now have you cleaned out the carbs? There could be a moving blockage in there.

And back to electrical - was coil ever checked or swapped? As Franny said it seems to be something common to both sides of the motor.
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Re: Diag: Recently running again but having some running iss

#52 Post by Harold Singh » Thu Oct 04, 2018 10:54 pm

Mervyn Hyde wrote:Good idea and that suggests at least that it is getting fuel to the carbs. Check to see if there is any debris in the fuel that was pumped out. Now have you cleaned out the carbs? There could be a moving blockage in there.

And back to electrical - was coil ever checked or swapped? As Franny said it seems to be something common to both sides of the motor.

The primary and secondary ohm test was in spec on the coil. I’ll get my plug tester out and check the spark quality at the end of the wire where it would go to the plug. Maybe even double check the new plugs continuity as well to be sure I don’t have a cracked plug.

Thanks,
Harold
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Re: Diag: Recently running again but having some running iss

#53 Post by Doug McDonnell » Thu Oct 04, 2018 11:07 pm

Harold Have you put a scope on it and made sure your distributor is advancing appropriately?
1965 356C There is never enough time to do it right, but always enough time to do it over.

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Re: Diag: Recently running again but having some running iss

#54 Post by Mervyn Hyde » Fri Oct 05, 2018 3:36 am

I agree Doug. I asked earlier if, when rebuilt, was it was curved and checked on a Sun or equivalent machine. I don't put much faith in the static setting process. Harold do you have a distributor timing light so you can test it at around 2000rpm (if you can get there, preferably 3000 where max advance is normally occurring)? Ron La Dow has a article that covers most of the issues https://porsche356registry.org/article/45

I use a timing light like this as I can check the advance at idle (static) and then the real deal at around 3000 rpm. https://www.amazon.com/gp/product/B000E ... ezvid02-20

Perhaps you could borrow a timing light, as most folk have one. I set the timing for my car around 33 degrees as this seems to be its sweet spot. What ever is happening is to all cylinders it would seem and a cracked plug on one cylinder is unlikely.
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Re: Diag: Recently running again but having some running iss

#55 Post by Harold Singh » Fri Oct 05, 2018 8:21 pm

Mervyn Hyde wrote:I agree Doug. I asked earlier if, when rebuilt, was it was curved and checked on a Sun or equivalent machine. I don't put much faith in the static setting process. Harold do you have a distributor timing light so you can test it at around 2000rpm (if you can get there, preferably 3000 where max advance is normally occurring)? Ron La Dow has a article that covers most of the issues https://porsche356registry.org/article/45

I use a timing light like this as I can check the advance at idle (static) and then the real deal at around 3000 rpm. https://www.amazon.com/gp/product/B000E ... ezvid02-20

Perhaps you could borrow a timing light, as most folk have one. I set the timing for my car around 33 degrees as this seems to be its sweet spot. What ever is happening is to all cylinders it would seem and a cracked plug on one cylinder is unlikely.
I have a 12volt timing light. I recall there was a way to make that work.
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Re: Diag: Recently running again but having some running iss

#56 Post by Mervyn Hyde » Fri Oct 05, 2018 8:38 pm

Good Harald. You will need a 12V DC source (external) for it to work. A 12V battery perhaps. For easy garage use, I found that up an old computer transformer unit with a fan, that connects to mains power, outputs 12V. Clamp the pickup lead of the timing light over the #1 lead and the + and - leads to the external 12 volt source (I assume you have a ignition 6v systems still) and then with engine running, look at the mark for the TDC mark on the crank pulley and see how that lines up with the reference mark on the engine case at idle - and then again a mark around 3000-3500 rpm.

Mine has another mark around 30 deg but this diagram shows where it should be.

Image

"As Ron suggests: somewhere around 3,000 to 3,500 RPM, the marks on the pulley and the reference mark should stabilize in the timing light beam. Note that data as you will. And, when you release the throttle, the engine should return to idle and the marks should again stabilize at the static value you found earlier. Again, note the data. Now you have both numbers. What is best for your particular engine is not established here, but the static should be between 4* and 8*. The dynamic should be between 30* and 36*. And they should both be stable."
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Re: Diag: Recently running again but having some running iss

#57 Post by Sean M Rooks » Fri Oct 05, 2018 10:17 pm

Harold Singh wrote:
Mervyn Hyde wrote:I agree Doug. I asked earlier if, when rebuilt, was it was curved and checked on a Sun or equivalent machine. I don't put much faith in the static setting process. Harold do you have a distributor timing light so you can test it at around 2000rpm (if you can get there, preferably 3000 where max advance is normally occurring)? Ron La Dow has a article that covers most of the issues https://porsche356registry.org/article/45

I use a timing light like this as I can check the advance at idle (static) and then the real deal at around 3000 rpm. https://www.amazon.com/gp/product/B000E ... ezvid02-20

Perhaps you could borrow a timing light, as most folk have one. I set the timing for my car around 33 degrees as this seems to be its sweet spot. What ever is happening is to all cylinders it would seem and a cracked plug on one cylinder is unlikely.
I have a 12volt timing light. I recall there was a way to make that work.
I borrow the 12V battery from my garden tractor because I'm too cheap to buy one just for timing. Works fine as connected per Mervyns instructions.

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Re: Diag: Recently running again but having some running iss

#58 Post by Doug McDonnell » Sat Oct 06, 2018 9:17 pm

My reading shows you can also just use a 12 volt charger as power source. And this link suggests that the internals of the timing light amplify the voltage to very high levels and 6volt will power it: https://www.stovebolt.com/techtips/timinglight.html If so ground to ground and positive to B+ at Voltage regulator clip on wire #1 and good to go.
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Re: Diag: Recently running again but having some running iss

#59 Post by Mervyn Hyde » Fri Oct 12, 2018 12:59 am

How did you go Harold?
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Re: Diag: Recently running again but having some running iss

#60 Post by Harold Singh » Sat Oct 13, 2018 8:47 pm

Mervyn Hyde wrote:How did you go Harold?
Ran out of time to do much. Worked late Friday and didn’t get to start. Saturday I aerated and seeded the yard before I got started. This afternoon I removed all the fuel. Put fresh ethanol free fuel in and after I checked the screen and cup under the tank and blew out the lines. Fuel was clear and no sediment was present.

My wife said she’d let me out of the pumpkin patch trip to check timing and work on cars tomorrow.
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