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Author Topic: Car has been runnning like crap for years. . .  (Read 8298 times)
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sicvic
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« on: May 12, 2014, 07:56:33 PM »

I know everyone's getting ready for the convention, but. . .

My 66 GT350 has a 289 with Windsor Jr. iron heads, a 292S Comp Cams cam, MSD 6AL, and an MSD distributor.  Built 15 years ago, low miles.  Road raced a few times.  Ran beautifully until I had two carb fires about ten years ago.  Hasn't run right since.  I have replaced the carb (two different ones), fuel tank, fuel filter (several times), engine wiring harness, replaced the MSD red coil with a stock one, new plugs, several sets of plug wires, cleaned various grounds, checked firing order several times.  I have tried various distributor spring combinations in the MSD distributor.

When initial timing is set to the stock 12 degrees BTD, the engine has no power below about 2,000 rpm; it's very hard to get the car out of the hole.  I now have the initial timing set at 30 degrees BTD (!), and it has decent power, but randomly misfires throughout the rpm range, and doesn't want to rev.  No preignition even with that wildly advanced timing.  Motor turns over easily and runs cool.  I am at my wits' end.  About the only thing I haven't repleced is the MSD box itself.  Could that be the culprit?

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zray
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« Reply #1 on: May 12, 2014, 08:37:48 PM »

Depending on the fire severity, and how it was put out, you might have as a substantial amount of debris in the intake manifold,  around the intake runners in the head, and on the intake valves. Have these items been removed subsequent  to the fire episodes, and cleaned ?

Z

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2112
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« Reply #2 on: May 12, 2014, 09:00:21 PM »

Just to answer one of your questions, I have had an MSD (and Crane and SVO) ignition box die for no explainable reason.

Isn't that why NASCAR cars have 2 installed, when one (word is not allowed)s the bed, they can immediately switch to the other?

I have also had coils and wires give similar symptoms, but you changed those out.

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gt350hr
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« Reply #3 on: May 13, 2014, 07:50:42 AM »

     Your problems are ignition related (IMHO) drop in a point distributor , set it at 12 initial and see how it runs. That will prove to you what's wrong. You've done everything else.
     Randy

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owner 6S477 HERTZ White w/Blue stripes-1of18-since 1974. OVER 3,500 drag strip runs made in it since then. My candidate for the "worlds Most drag raced Shelby" More added all the time.
waterboy
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« Reply #4 on: May 13, 2014, 08:40:55 AM »

Check compression on each cyl., might have a blown head gasket or bad valve.

« Last Edit: May 13, 2014, 11:46:51 AM by waterboy » Logged
Kiwi
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« Reply #5 on: May 13, 2014, 09:20:29 AM »

During the fire(s) you may have melted nearby wires. Even if electricity is still flowing through the wires, it might not be the proper amount and/or the resistance may be off. Or, maybe there is some type of arching between the wire(s) and a nearby metal object. Regardless, full electrical power is not getting to the intended source.

With my car, I upgraded to an aftermarket coil that needs a constant 12 volts input to work properly. If you use the original ignition switch power source a full 12V will not be delivered to the coil. As a result, the car started and it ran OK during light throttle. However, during heavy engine loads and/or during high rpm the engine was weak and would start to miss at higher rpm. The reason why I'm telling you about this is because if some of your wires are fried/melted (such as the power wire to the coil) then a similar thing may happen during motor use as the coil is not getting the proper amount of power.

The other thing that could be happening is if at some time the key was left in the on position and the ignition coil got fried (or melted down to some degree) inside. I had this happen once years ago and the result was the same as my above problem the engine would start and run, but ran crappy as revs built.

Try this:

1. As a temporary test, use a (fused) jumper wire from the battery to the coil input. Start and drive the car to see if the problem goes away. If so, then you know it's a wiring issue to the coil. [Note: the car will start, but with direct power to the coil the engine will not shut off when you turn off the key. Thus, you will have to remove the wire from the battery to kill power to the coil. But this is just done as a test and is not a permanent fix.]

2. If #1 doesn't work, switch the current coil for another known/working coil. Personally, I'd still use direct power from the battery to the coil during the test which will eliminate any possibility of bad wiring from the in-dash ignition switch. If the car runs well then you know the coil is bad/fried.

3. If you are running an external ignition box (MSD or such), either try another ignition box or disconnect the box and just run the normal coil (the car should run this way). If the problem goes away, then you know it's the aftermarket ignition box.

3. If #1, #2, and/or #3 don't work, try Randy's suggestion of switching out the distributor.

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camp upshur
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« Reply #6 on: May 13, 2014, 10:24:55 AM »


sicvic,
 
You have done a lot of sensible troubleshooting and parts replacement ($) related to spark, and fuel delivery. Unfortunately to no avail yet. Perhaps time to step back and assess.  (I have a veritable speed shop on my shelves of parts I've bought chasing problems)
It could be a ballast resistor related issue as mentioned, which is easily and cheaply troubleshot as mentioned.

Your comments about unusual timing needed to get engine to run marginally, random misfires and nonsensical performance are all indices of the camshaft-crankshaft relationship being slightly off (i.e. chain jumping a tooth).

Just something to think about. Good Luck.

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acman63
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« Reply #7 on: May 13, 2014, 11:57:45 AM »

I had a 66 GT350 in here awhile back that had a similar proble,.  we finally figured out that the outer ring on the balancer had moved and we had to time it about 40.  sent the balancer out to get redone and it solved the problem.

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corbins
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« Reply #8 on: May 13, 2014, 06:45:47 PM »

Another though...timing chain has jumped a tooth or two. There is no reason to have to run that much initial unless something is wrong somewhere else. I agree with most of the above, I'd put on a know good dizzy and coil, time it at 12-14 initial and see what it does , If it still running bad, you have a problem elsewhere. Have you ever checked for a broken valve spring? Just a thought...
Good luck, let us know what you find out.

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stickshift
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« Reply #9 on: May 14, 2014, 03:53:37 AM »

The smart money is on the balancer. This has become all to common of an occurrence. The balancers are glued together and at some point it gives up and causes exactly this scenario. At this point they all should be rebuilt.

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gt350hr
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« Reply #10 on: May 14, 2014, 08:00:52 AM »

   Check the dampner by pulling #1 spark plug and turning the engine over until the piston is at tdc ( close is OK). Then look at the dampner and timing mark to see if it reads "0" If it's off 30 or so degrees , the ring has moved.
      "Jumping teeth" on a non nylon timing gear is near impossible.
   Randy

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owner 6S477 HERTZ White w/Blue stripes-1of18-since 1974. OVER 3,500 drag strip runs made in it since then. My candidate for the "worlds Most drag raced Shelby" More added all the time.
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« Reply #11 on: May 14, 2014, 09:03:34 AM »

......"Jumping teeth" on a non nylon timing gear is near impossible.
   Randy

Randy,

Not saying this is the case with sicvic's problem but....wouldn't an original 66 HiPo cam timing gear have nylon coated teeth?

Dave

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Dave
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gt350hr
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« Reply #12 on: May 14, 2014, 09:31:47 AM »

    Yes Dave it would! 40+ years later , I would hope the original isn't still in there but IF it's a low mileage car it's possible. The nylon teeth crack and break off from heat ( normally) and high mileage. I have seen "new" ( crate) engines 40+ years old and the nylon gear is still perfect, so a low mile part could still be OK. The point is it's almost impossible to get a chain to jump IF there are teeth on the gears.
    Randy

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owner 6S477 HERTZ White w/Blue stripes-1of18-since 1974. OVER 3,500 drag strip runs made in it since then. My candidate for the "worlds Most drag raced Shelby" More added all the time.
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« Reply #13 on: May 14, 2014, 01:21:30 PM »

Something  let go to cause a fire to your carbs. most likely its  timing,  not ignition.     use a vacuum gage to trouble shoot before you replace everything.

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Kiwi
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« Reply #14 on: May 14, 2014, 07:57:03 PM »

Something let go to cause a fire to your carbs. most likely its timing, not ignition.
Which further confirms what acman63 and gt350hr said.

« Last Edit: May 14, 2014, 09:45:41 PM by Kiwi » Logged
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