914-6 carb question Options

[carcam]

Long time Porsche owner new to 914's except a college car (1.7 L) in the late 70's. Just picked up a nice 914-6, complete restoration about 10 years ago and I love it. The engine is basically stock, bumped to 2.2 L with a Solex grind cam, nothing else. On a recent local Porsche club event, the guys behind me couldn't take the strong gas fumes and my clothes do smell like gas after a long run and it sucks down the gas- haven't checked the mileage but it's no Prius. Obviously running too rich or something. I don't want to jump into these Webers myself and the car runs, starts, and idles perfectly. Strong mid range and awesome above 4,000 rpm. The previous owner says it's dialed in and all the old carburated cars are like this and that's why everything now has fuel injection. I don't have any local Weber experts and the techs I've talked too are reluctant to mess with such a good running car. Any advice? Change of clothes, add AC and roll up the windows, switch to fuel injection or turn a couple screws and problem solved. I know this is a very technical forum and something most of you could fix over a beer or two but this is all new to me. Thanks for any advice.

[SLITS]

Is your heater hooked up? If the body tubes are not connected you will suck engine fumes into the drivers compartment. No heater .... cap the body tubes.

Is your Fuel Evaporative System hooked up? If not and on a full tank or thereabouts you will get fuel fumes in the drivers compartment.

A couple of simple things to look at.

[70Sixter]

The plastic fuel lines that run thru the tunnel to the engine can crack and leak to the point of risking fire. Get the stainless replacement if your car doesn't already have them.

Also the lines and the fittings at the carbs can leak or seep gas if they are old. Also check the filter in the engine compartment.

And spray paint can tops block off the heater at the engine nicely if that is a problem.

Too rich mixture results in black soot in tailpipe. Some of us run a bit rich just to avoid too lean burning and associated fried engine.

[Cap'n Krusty]

The plastic fuel lines that run thru the tunnel to the engine can crack and leak to the point of risking fire. Get the stainless replacement if your car doesn't already have them.

Also the lines and the fittings at the carbs can leak or seep gas if they are old. Also check the filter in the engine compartment.

And spray paint can tops block off the heater at the engine nicely if that is a problem.

Too rich mixture results in black soot in tailpipe. Some of us run a bit rich just to avoid too lean burning and associated fried engine.

Have you ever personally SEEN the fuel lines in the tunnel crack or leak? I've been working on 914s for a living for 35 years, and have NEVER seen this happen. NEVER. Let me qualify that. Never unless someone damaged them, like when welding, cutting, or drilling.

FI cars sometimes have heat and stress related (or, more commonly, ham fisted mechanic induced) damage in the area AFTER the tunnel, but never (!) inside the tub.

The Cap'n

[dug]

Follow the above suggestions to check for fuel leaks.

I had a 914-6 with Solex cams in a 2.5 liter short stroke engine. In order to eliminate a bit of a flat spot I increased the size of the idle jets. It got rid of the flat spot, but it had the same effect you describe of making following teeners eyes water.

In this day and age of modern technology, guessing what to do is silly, and bad for your engine.

I suggest you invest in a quality wide band air fuel meter. For around $400 you can get one with dual inputs and data logging. The Innovate Motorsports (no affiliation) LM-2 is the most accurate A/F gauge according to a magazine shoot out of all the top brands.
http://www.innovatemotorsports.com/

This will allow you to monitor both banks of carbs and watch your A/F ratio while you are driving under load. Then you will know exactly how rich you are running and tune the carbs without doing a bunch of guess work and basing your decision on your nose.

cheers,
dug

[carr914]

carcam, (IMG:style_emoticons/default/welcome.png)

T.C.

[carr914]

And as Raul Julia said in Cannonball Run said, " What's behind me is of no importance".

They were jealous they didn't have a Six.

T.C.

[carcam]

You guys are the best- great forum. Thanks and I'll check into all the above.

[GeorgeRud]

Remember, today's gasoline has a higher Reid vapor pressure than when the car was built, so it will perculate in the carb float bowls sooner than before. Turning off the fuel pump a block or so before parking will help lower the float levels so it won't overflow, but it is a problem.

Going to fuel injection will not have the fuel exposed to the atmosphere, and would help, but it isn't free to do the conversion.

I think the suggestion to get the air/fuel meter makes a lot of sense in trying to dial in the carbs.

[Seaside6]

I had similar issues when I first got my car in November, 2003. I tried reducing the idle jets but it did not help.

A friend with early 911 experience showed me a trick that totally fixed the problem - we removed the idle jets, one by one, and blew compressed air through the jets and the openings that the jets came out of.

The low end flat spots were totally gone and the super-rich exhaust smell cleared up. The car immediately had increased power, was real smooth all the way up, and I am sure it was performing as Porsche expected it to when it left the factory. As far as I am concerned it might as well have fuel injection. And, I was able to return to the larger idle jets.

As time went on the degraded performance would reappear and I would go through the compressed air routine and the performance would return. The problem was that sediment from the fuel tank was clogging the carb and compressed air was moving the current obstructions out. Replacing the fuel filters never helped, the sediment was still getting through.

I finally pulled the fuel tank and had it teated by a radiator shop and the problem never returned. The car continues to run great.

[WaideS]

And as Raul Julia said in Cannonball Run said, " What's behind me is of no importance".

They were jealous they didn't have a Six.

T.C.

AWESOME a Cannonball run quote to start off the weekend........Thank you for that

My thoughts when people "complained" of the smell of my carbs/exhaust is they were jealous I could beat them up the hill. If you convert to bio-diesel and they'll complain it smells like french frys....You can't win (IMG:style_emoticons/default/laugh.gif)

[carcam]

Thanks everyone for the great ideas. And I love the smell of french fries!

And as Raul Julia said in Cannonball Run said, " What's behind me is of no importance".

They were jealous they didn't have a Six.

T.C.

AWESOME a Cannonball run quote to start off the weekend........Thank you for that

My thoughts when people "complained" of the smell of my carbs/exhaust is they were jealous I could beat them up the hill. If you convert to bio-diesel and they'll complain it smells like french frys....You can't win (IMG:style_emoticons/default/laugh.gif)