tune up questions

[xexitenglishx]

I am new here and i just started fixing up a 79 911sc i have had in the garage for a few years. After letting the car sit it has been running alittle rough on a cold start. If i start the car cold and try to rev the engine at all it will stutter and sometimes backfire until it is warmed up. What could be the cause of this?

I was going through the basics and checking the spark plug wires. I noticed when if i pulled one of the wires and started to car the spark would arc from the outside of the spark plug connector. Should this happen or could the wires be going? They are the original wires btw.

Also the heat exchangers have pretty much rusted through and i plan on replacing them eventually but im more worried about getting the car running right first. There is an exhaust leak in the crossover pipe from the passanger side header. would this cause poor drivability due to the loss of back pressure?

Thanks for the help

[Mo_Gearhead]

QUOTE: "They are the original wires btw"
___________________

You don't mention the mileage but ...original wires on a 79? I would start there (replacing plug wires) and dist. cap, rotor and new spark plugs. A general tune-up.

As you stated, deal with the exhaust later.

[Gunter]

Sitting for a few years?
Did you run an injection cleaner through the system before storage?
If not, do it now: 2 bottles on a full tank.
Did you fill the tank before storage?
Turn the engine over periodically?

Replace the original plug wires (And plugs?) with new ones.

[xexitenglishx]

sitting because it was uninsured. Injector cleaner wasnt run through before storage but i put seafoam in the gas tank now and i also ran it through the vac line. Tank was full on storage and the car was started every 2 weeks or so. Plugs were replaced before storage should i replace them again?

[Gunter]

Plugs should be good.
Don't know what seafoam is or what good it would do in vac lines.
Fire extinguisher near by.
To check injector performance/spray pattern and volume, pull the injectors, put them into 6 small glass jars, remove airfilter cover, ignition ON, lift the fuel distributor/airflow scale for a few seconds.
Ignition OFF. There should be an equal amount of fuel in the jars.

[Paulporsche]

Proper backpressure is important in getting the most from these engines. It's hard to know how much of a problem, if any, your exhaust hole causes.

You should do a search. You will find that on these cars an out of spec or malfunctioning WUR with a too high control pressure causes a lean condition during warmup (and sometimes beyond) that results in the symptoms you mention. You can buy a pressure gauge from JC Whitney that will let you check the fuel pressures. There are many threads here on checking this and adjusting the WUR. The AAR could also be malfunctioning, or the mixture could be set incorrectly.

You should also get the Bentley manual.