engine sputtering, tachometer fluttering

[Scutty]

After a lengthy storage and recent carb work, I'm trying to get the backfiring and missing out of the engine. The car is a primarily stock, I'm told it has a hot cam, I'm running rebushed solex 40PIIs. The car has been in and out of storage and hasn't ever run well for the 4 years I've had it. I've recently replaced wires and plugs, cleaned and reworked carbs, I'm about to replace my 009 with an 050.

I noticed something while driving last evening. The tach drops off when the car misses and looses power. When the car runs fine (only lasts for 5-10 seconds) the tach is steady, but when the car sputters, the tach wavers violently from 1000 to 4000. I'm in gear and cruising at speed, so I know the actual engine speed is near constant.
The tach gets it's signal from the coil, right?, so does the wavering tach indicate the sputtering is caused by a bad coil? or condenser? or distributor?
Please give me all your thoughts for the driving the demon out of my prized possession.

[wastintime]

How lengthy was the storage?

[Scutty]

I had the engine rebuilt by some untrustworthy mechanics in 97. I drove the car (poorly) the summer of 98 and 99. It's been in storage since then, the carbs, plugs, and wires I did last month.

[WFBowen]

Scutty:
I'd definitely get a new distributor in there as your current one might be shorting, especially under advance plate movement. As you mentioned, you might as well stick another coil in there while you're at it & double check all of your wiring for loose connections, etc. I wouldn't be revving the motor too much until you're sure you've got this problem licked - high speed miss can cause a lot of things to come unglued, especially in an aircooled motor. Are there problems in other electrical circuits?
Good luck,
Bill.

[Scutty]

As far as electrical problems, the more I look, the more I find. Probably 10% of the time when the key is turned I don't get any noises at all. After smacking the battery connections or rolling from my downhill facing parking spot, it does start. Maybe a weak ground or a weak battery?
My green dash light is out with the key half turned, but I've got an aftermarket VDO gage. No left turnsignal, no horn. I've got my work cut out for me.

You weren't specific, what damage can high rpm missing do?

I'm still wondering what would cause the erratic tach movement, any ideas anyone?

[craign]

Scotty,

I had the same problem with the Tach, after running for a while it would swing wildly where from 2-6k, while the engine and MPH stayed constant. I cleaned the connections on the coil and made sure they were real snug and have not had a problem since. I have a Bosch blue coil I am going to install but need to pull the generator/fan assy since I have a backing nut that is turning with one of my bolts on the existing coil clamp. I should be able to reach it throught the fan hole once it is off.

Craig

[Scutty]

Did your car cough and choke in harmony with the swinging of the tach? I can understand how bad wiring from the coil to the tach would send an intermittant signal and give a swinging tach needle. What I have got, I believe, is different. Something is causing an engine miss and it's also screwing with my tach.

[craign]

No sputtering and choking but a severe high idle problem when hot. I put in a new distributor and syn'd and tuned the carbs for that one. I wasn't getting a full "spring back" on the old distributor when hot.

[jac912]

Electrical prob's are hard to trace unless you've personally followed all the wiring and know what they all do. I got mine running great last summer then had a very similar experience to yours. While driving, usually in the 2000-3000 rpm range the engine would cut out momentarily with the tach diving to 0 immediatley. Usually it would fire up after a second as ignition was still on and wheels are turning. Turned out to be a bad ignition switch. $7 at Advance Auto Parts for the simplest unit they had.
Jim in Ma.

[C. Clark]

Hello,
Popping, back firing, in my case was carb problems, to lean / to rich, generally out of adjustment or sucking air from the butterfly stems or somewhere. I replaced the Solex carbs with Webers. While I was at it I read here that the .050 dist. was the way to go. Roland Kurtz the resident Porsche guru called the .009 a engine killer, I'm really not sure about that.
Since your tach is acting wierd the dist. may have something to do with it since the dist. produces the signal that is sent to the tach.
The longer I'm around this stuff the more I realize it's either spark or gas in most cases. Those old Solex's can be a real problem.
Good luck and Happy motoring,
Chas.