1971 porsche 911 does not stay running without hitting throttle

[khan654]

Hi,

My 1971 911 T with Weber Carbs does not stay running unless I hit accelerator.
This car has been sitting for almost 10 years.
Replaced the gas tank, fuel tank screen, new pump, fresh oil, new filter, new battery, new spark plugs.

When I hit the gas, it spits fire from random throttle bodies. I removed jets which sprays gas when you hit gas. It was easy access and sprayed with some carb cleaner.. few were blocked.

I am not sure if I need to remove the carbs and refurbish it?
Or if the Rotor timing is off? or Float Bowls are letting too much gas inside the cylinders?
Rotor timing was not touched since I acquired. I tried adjusting idle screws hoping it will idle. But the problem is it doesnt even stay started with spitting some fire and without hitting gas. So, Idle screws can only be adjusted if it was idling bad.
Can it be air mixture?
Did anyone had this issue? BTW, I get 3PSI of fuel pressure when I put the key in start position.

[yelcab1]

Carbs sitting for ten years and ... you were hoping it would just run? No such luck. Pull the carbs, rebuild and clean orifices, resynch them up on installation.

My guess is there is a lot more you have to do to get this car running safely.

[khan654]

I agree I would need more to have it running safely. I was hoping (which is not a bad thing ) that it will start and then I can update/refresh parts slowly...

I will hopefully remove the carbs today, clean them and put on new gaskets and float bowl adjustment screws.

Thank You.

[nickelplated5s]

Drain the gas and put fresh in, preferably non ethanol. Older carbs tend to not like ethanol flavoring. Flush the fuel lines and you might get it running but I'd still go through the carbs.

[gamin]

Agree on carb rebuild. Care with brass fittings. Throttle shaft bushings worn? Is the timing set correctly? All fuel lines must be clean front to rear with all rubber lines replaced with new ethanol resistant ones. Get a better fuel filter. Fuel pressure 3-4 psi. If available, always use non-ethanol fuel. If you leave ethanol fuel in the bowls for an extended period of time it will kill those expensive webers. Fun project.

[khan654]

Removed the carbs, cleaned it.. some had blockages.
The copper float bowl plug got broken. I didn’t even put any pressure… the carb cleaner spray is, I think making those copper fittings very dry.
Lessons learned, I ordered new bowl plug.
Both the carbs are clean. Didn’t rebuilt it cus the kits we’re selling gaskets and push pin for bowl.
I didn’t not adjust the float bowl at all, removed the pin, cleaned the bowl area and put it back.
Now I think the issue might be with ignition timing. And I am not experienced enough to make adjustments like top dead center and lining the cylinders etc.
Not sure what I can do at this point. No Porsche mechanics close by too
Parts Klassik in NYS technician does consultation for $176/hr.
Too pricey but I need to see my options..
The tutorials on YT are not really detailed.
The gas I have is with ethanol, I’ll drain it and get non ethanol tomorrow.

[HarryD]

Chances are your ignition is close.

This article maybe helpful to you: https://www.pelicanparts.com/techarticles/101_Projects_Porsche_911/22-Ignition_Tuneup/22-Ignition_Tuneup.htm

Also this one: https://www.pelicanparts.com/techarticles/101_Projects_Porsche_911/23-Timing/23-Timing.htm

If you do not want to do it your self, find a hot rod shop near you. They should know how to set points, dwell and timing. Nothing magic about it for a 911 motor.

[khan654]

Is there a good video or anything you can recommend to adjust it by myself?
Also I have NGK Iridium spark plugs... what gap (in Inches/mm) should it be for MSD ignition, Weber 40 IDA, 2.2L engine.
The fuel pressure on the gauge shows 3PSI when I put my key in start. Sometimes it goes below 3.. doesnt stay consistent.
What should be the fuel pressure?


Thanks.

[HarryD]

Originally Posted by khan654

Is there a good video or anything you can recommend to adjust it by myself?

The articles I posted above tell the story.

Also I have NGK Iridium spark plugs... what gap (in Inches/mm) should it be for MSD ignition, Weber 40 IDA, 2.2L engine.

I use NGK BPR7ES with good success. Gapped to 0.028. Some suggest opening them up to 0.045 for a MSD.

The fuel pressure on the gauge shows 3PSI when I put my key in start. Sometimes it goes below 3.. doesnt stay consistent.
What should be the fuel pressure?


Thanks.

Around 3 should be ok for carbs.

[khan654]

Is that spark plug gap in inches or mm?

[HarryD]

Originally Posted by khan654

Is that spark plug gap in inches or mm?

Inches.

[khan654]

While cleaning the carbs, I observed the needle seat for float bowl doesnt really work as expected. The ball inside the needle is getting stuck, maybe thats filling up the float bowl.
Ordered those and a bolt was broken (since they made of copper)
God willing once I assemble it back, it should start.

[deemsriddle]

Marvel Mystery Oil has worked for me in the past. I bought a 1969 911S in the late 1990s that had sat for 20 years. It had a freshly rebuilt engine that had never been installed in the chassis, much less started. I got it started easily enough but it didn't run particularly well. It was in the paint shop and the painter got it running perfectly. He mixed the Mystery Oil in the gas tank per factory directions. After that he started the car and poured small amounts of the Mystery Oil down each throat a little at a time. I have used that technique several times in the past. It's not particularly expensive and does work.

[khan654]

I did put mystery oil inside the spark plug holes. Left it for a day.. gave a whiff of ether and started it. This was when I first bought...
Now I have cranked and started it enough.. fresh oil too.
the problem I am facing is, it doesnt stay running unless I keep pressing throttle...
Also there is misfire from random cylinders when I press throttle.

[HarryD]

Originally Posted by khan654

While cleaning the carbs, I observed the needle seat for float bowl doesnt really work as expected. The ball inside the needle is getting stuck, maybe thats filling up the float bowl.
Ordered those and a bolt was broken (since they made of copper)
God willing once I assemble it back, it should start.

Originally Posted by khan654

I did put mystery oil inside the spark plug holes. Left it for a day.. gave a whiff of ether and started it. This was when I first bought...
Now I have cranked and started it enough.. fresh oil too.
the problem I am facing is, it doesnt stay running unless I keep pressing throttle...
Also there is misfire from random cylinders when I press throttle.

Sounds like your plan to get the Carbs cleaned, sealed and adjusted is the next step.

[khan654]

Yes, I have cleaned the carbs.
Waiting on few pugs/jets t put it back again. Once ready, will try to start it again.