I think I know now what is wrong....all advise appreciated.

[Reg]

Hi all.

If some of you regulars have been reading posts about my car, you will know I have been having troubles with its engine since purchase 2 months ago.

If you havent read any, well my car is a '70 911T and was sitting for some 4 to 5 years in a garage before my purchase.

I have flushed the fuel tank twice, changed the oil once, ran chevron fuel system cleaner thruogh, also used a can of carb claner(for webers), replaced the fuel filters, changed the plugs twice, bought a new cap and rotor(bosch), as well as a new set of wires, and set the timing. Not all in that order.

My problems were my car started and idled ok, but once driven a few miles, the car would bog down and quit. After some 5 minutes rest, the car would fire up , clear its throat and away you go. It also backfires on decel, and pops a bit too.

At times it seems to run fairly good, and pull nice from 4k to 6k rpm ,but I did not push it too much...just tried to clean it out.

Now after installing new correct plugs along with the new wires I have found cylinder number 6 plug to be clean as new and slightly wet after 40 miles of driving. All other plugs were medium to lighter brown with some black on the edges at the threads. I should note that the car did not bog out nearly as badly initially ,but still did more so between 30 and 40 miles driven with the new plugs/wires/cap/rotor.

I removed the new plug wire from number 6 and there is spark, and I guess that tells me why I could hear a slight miss at idle. The car ides the same when i remove that wire while at idle.

I am getting fuel as my clear filters are full when the car bogs to a halt, and I am getting spark from the coil , turning the key after stops after stalling out with the wire removed from the cap.

What is my next move? I am thinking expense here, but have no idea what I may be into. The engine was rebuilt some 30k miles ago (about 10-12 yrs ago).

Any help , insight or advise would be great.

[jeff parker]

If you have a Permatune, replace it.

------------------
Jeff Parker
72t

[Reg]

Hi!

I have the bosch CDI unit in the car. I do have spark at the plug, but the cylinder is not working.

I'll be the first to say I am no mechanic, and those who have read my posts must already know!

[Early_S_Man]

Reg,

Get a couple of gallon cans of the vat or 'dunk' type carburetor cleaner (only 3 qt. or so per can -- you will need more) and a large metal pan or tray big enough to put one carb. in it. Get the Haynes Weber manual ... remove carbs and disassemble them one-at-a-time, and soak all of the metal parts in the cleaner for however long the instructions on the can say. Rinse off everything with water and blow out all passages with compressed air -- a portable tank will work fine. Webers are easy to disassemble, and each of yours is a mirror image of the other, hence the reason for doing them one at a time! It is an easy process if you don't get overwhelmed by the complexity of the diagrams!

Your engine runs off the idle circuit well beyond 3000 rpm, so there is probably gunk and deposits clogging up your main jet distribution circuits, and the vat-type cleaner is the only way to clean it out. They will look almost new when you get through, and you will have overcome one of the major fears about Webers -- that they are hard to work on! They aren't!!! Get two rebuild kits and manifold gaskets beforehand, but if you are careful and lucky ... you may not need all of the gaskets.

Good luck!

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Warren Hall
1973 911S Targa
1992 Dodge Dakota 5.2 4X4 parts hauler

[fred cook]

Reg,

Just thought I would share something that I learned about cleaning carburetors a while back. The outside of the carbs usually wind up with a dried varnish looking goop that is actually old gasoline. An easy way to really get the carb bodies clean is to get a can of spray bumper sticker/paint remover. After completly stripping the carb, put on a pair of rubber gloves, and spray the carb body with the paint stripper. Let is "soak" for about a minute, and scrub it down with a stiff bristle toothbrush. Rinse off with cool running water. If the carb is particulary nasty, it might take two applications. Do not, I repeat, not let the paint stripper stay on the carb body more than a few minutes. This stuff will leave permanent stains on the carb if left to dry. The finished product should have the glossy sheen that makes newly cast parts look so good. Good luck.

80 911SC

[Superman]

Warren knows his stuff, as we all know. My advice was going to be less specific, but similar. Your symptoms remind me of various 'ditry fuel system' problems I have seen. I'd advise blowing out the fuel lines while the carbs are off, and possibly draining and rinsing the gas tank. Replace all filters.

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'83 SC

[Reg]

Thanks for the posts.

I heard a hissing sound from the passenger side carbs when I had the air box off, and it was suggested that I could have a problem internally such as a bad ring or valve.

I should note that when I attempted to adjust the carbs with a synchrometer, the carb over 6's air screw was and is seized.

I do not have a local shop nearby where I can get this work done. Closest shop is where the PO had the car worked on, and I'd kind of maybe rather not go there.

There are very good shops available, but are 2 hours away , and likely miles away from my budget too!

I can see this car ending up there in pieces!

I wonder how well Wayne's book covers the carb rebuild subject.

Thanks again everyone. I am working on the car Sunday.

[Zendalar]

My problem was like yours with the cylinder number 6. At idle it did not matter if the spark plug wire was attached or not. The car also smoked, a lot. I did a compression test and it showed almost zero compression at #6.

I got many advices what to do and one advice was "Abuse your car, not too much, but still abuse it."

Guess what? The compression came back to cylinder #6. It was just stuck piston rings and needed some driving.

[john walker's workshop]

the carbs were zeniths originally and they need a bit more effort than webers to get functioning properly. a good cleanup is the first step, with new float valves, seals and gaskets. i just did a 70 that was sitting for 8 years and the dead gas completely rusted the inside of the gas tank, requiring replacement. the carbs were varnished inside where the dead gas had evaporated, and took a lot of cleaning effort. a lot of the jets and check valves for the squirters were varnished and gummy and it was good i had some parts carbs for parts. the gummy varnish is difficult to remove because carb cleaners are weaker than they used to be and won't dissolve the stuff. enlarge the idle jets to .55mm to get rid of the spitting and popping.

[Reg]

I am going to swap a plug too.

Maybe I got a dud from Bosch?

So, if I drive the car now , am I apt to hurt it by attempting to drive the sticky rings free?

[Zendalar]

It did not hurt in my case and if there is little compression in the #6 then that cylinder is getting enough oil so at least it won't...well..get stuck.

If the valves and carbs are adjusted and carbs clean, I would at least try to "drive" the rings loose.