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Old 10-26-2004, 07:11 PM
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350 Sputtering

I have a '70 Chevelle, and I recently pulled apart the whole front end to do some painting, rewiring, and to replace the fender wells. When I put everything back together everything seemed to run fine for about a week. Now between 1500-3000RPM it sputters like its runnin on 4 cylinders. Another interesting quirk is that the alternator is charging constantly at 16 volts. I've tried playing with ground wires, grounding the ignition directly to the battery and whatnot but no matter what i do it seems I get no change in the sputtering problem. I'm sure I'm missing something simple but as for now I'm stuck.

-THX2000

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Old 10-26-2004, 07:18 PM
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Your regulator is up front by the rad, right.............?

wonder, if you rewired it wrong, or shorted it out. May affect the ignition too..............
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Old 10-26-2004, 09:08 PM
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Some questions..

Doc here

Is the battery going totally dead? If so you may not have enough power to run your coil at high rpms...

Is the ignition HEI or Points type? If points type, did you reconnect the resistor/resistor wire (cotton bound wire)? If not and your reading 12 volts at the coil...change your points, and get a resistor...they are probably burned up.

Is the Alternator Internally regulated? or do you have an relay type regulator? Do you have 12 volts there at the Battery terminal?

Are you reading 16 volts across the battery or elsewhere? Sounds like you have charge, but it isn't reaching the battery...

More info, please

Doc
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Old 10-27-2004, 06:37 PM
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Ok, heres a little more info on what I have and what I have done. I have an MSD Ignition with the 6A box and a holley 750 double pumper. It was running fine before I pulled the front end apart, so some of the things I did while redoing the front end. Pulled booster and master cylinder out and painted it, new power steering pump, pulled off both fenders and replaced the fender wells, pulled out all the relays to allow for painting, pulled all plugs and wires, and pulled off headers in order to repaint the heads, relocated MSD box to the firewall (was previously on fenderwell), shortened wires from MSD box to Distributor and from MSD box to coil. This is a fairly fresh engine (about a year old), with aprox. 4000 miles on it.

Ok, on to things I've tried to troubleshoot the problem. Replaced plugs, checked and rechecked the plug wires to make sure they were seated properly, removed the fuel filter from the pump to the carb and replaced it with a straight hose, checked the float levels, made sure the needles were clean, removed the alternator completely from the mix and wired the ignition directly to the battery (thought the high voltage could be causing problems, battery shows 13 volts), beat head senslessly into hood, and thats about it.

Thanks,
THX2000
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Old 10-27-2004, 06:44 PM
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If I were you I would plan on spending the entire weekend tracing every wire under your hood. I would bet the problem lies in there. It is hard enough to trace them when you are working on the car, let alone trying to do it over a message board.

Not trying to be rude so I apologize if I come off that way, but it sure does sound like an electrical issue and you are just going to have to spend the time making sure you didn't chafe a wire or something.

Good luck!!
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Old 10-27-2004, 06:47 PM
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Does it do this under a load or just rev at a stop? One thing I would check to is your coil. Take it somewhere to have a load test done or borrow one to try. Can't hurt.
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Old 10-27-2004, 07:16 PM
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If I have the ignition directly wired up to the battery, wouldn't that pretty much eliminate the problem of any other wiring being faulty? The only wire thats running through the car is the switch for the ignition, and theres really no serious voltage running through that so i dont see why that would be a problem. If I'm wrong let me know, I've still got lots to learn.

Western Star: It idle's fine, starts fine, and above 3000 it runs pretty decent, but between 1500-3000 its missin like crazy.

-THX2000
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Old 10-27-2004, 07:45 PM
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Ya it sucks when you can't figure it out. My mind races at night or trying to sleep hoping to find the answer. How long did the car sit? What about moisture in the fuel. You could always try running a seperate fuel line into a can of fresh gas. That would eliminate that end of it. There's some pretty smart people on here for input. It's certainly better to be standing in front of your engine.
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Old 10-27-2004, 08:04 PM
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Grounds

Doc here

Have you tried Running a Ground from your fender-wells

(Sorry, your going to have to burnish that new paint...)

with a star-washer,Then to the firewall (at the MSD box)with a star-washer, and then back down to the alternator mount bracket and then at the engine Block ground.
(That should be the same 1/0 cable going directly to the battery)
... in a daisy chain ?

Use 10 ga or better wire to run your new grounds.

And be sure Your Battery Cable goes directly from the battery, to your ENGINE block, Somewhere around the starter, Then to the frame, and tie your new daisy Chained ground to that ground.

This should straighten up your alternator too.

Are you using an Ignition Resistor? and does the MSD require one ? (check your MSD book) You may have to remove it if it doesn't require one.

Try that and we can go from there...

Doc
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Old 10-28-2004, 07:22 PM
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Thanks for the help guys, turns out the sputtering problem was due to moisture in the distributor. I never got around to putting on the new hood seal and with the recent rains we've had in CA some moisture seeped in.

-THX2000
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Old 10-29-2004, 12:56 AM
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KEWL!

Doc here

Simple is good!

Glad to here you got it resolved!

Had that happen to my 80 Vette when I "Gunked" The engine...popped through the Carb for 2 days no matter how often I dried it...turned out the coil was wet and dripping into the Cap...

Rock on...

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Old 10-29-2004, 07:45 AM
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Don't you just hate it when something so simple causes all that trouble?

Had it happen to me. Cruising along down the highway and all of a sudden the engine just starts backfiring. Had to stop it was so bad.

After calling for a ride, getting tools and coming back to the car, turned out the radiator had a pinhole leak and was shooting this little teeny stream of coolant directly into the dwell adjustment window on the distributor.

Glad you found the problem.
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