# '66 engine damage?



## Alan (Jul 8, 2006)

Hi, last week I took my '66 GTO for a ride. All was OK for first mile, then started running rough, then stopped. I tried hard to re-start the engine, until it backfired so loud that it sounded like dynamite. I flatbedded it home to my garage. A few days later I tried to start again, same loud backfire. Then I noticed that I can turn the rotor easily by hand, so I think the timing chain broke or jumped. Question is, did those backfires do any damage to the engine, and how can I tell?


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## Rukee (Feb 8, 2007)

No, it shouldn`t damage the motor, might blow the mufflers open, but it shouldn`t hurt the motor.
If you can turn the rotor, I`d suspect the distributer gear might be broke, or a sheared roll pin if it uses one. If it was the timing chain, you`d have to be turning the cam too(opening and closing the valves) when you turn the rotor, and I don`t think you`d be able to do that.
Welcome to the forums by the way.


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## Alan (Jul 8, 2006)

Thanks for the reply Rukee. I was just about to start on getting at the timing chain, maybe should hold off on that. Now thinking that if I pull off one of the valve covers and turn the rotor I can tell if the problem is the chain or the distributor gear. Unless someone can suggest any easier way to diagnose which one it is. Thanks again.


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## Rukee (Feb 8, 2007)

Just mark the location of the rotor and distributer housing, and pull the distributer out. I`ll put money on that`s where your problem is at. 


The angle of the gears there at the cam and distributer makes it very easy for the cam to turn the distributer, but very hard for the distributer to turn the cam. Unless possibly the very end of the cam is snapped off I wouldn`t think you could turn the cam from the rotor.


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## Alan (Jul 8, 2006)

Rukee you were right. I pulled the distributor and found the gear pin sheared off. The gear was fine but turning freely on the shaft and came right off (lucky it didn't drop into the engine). I'll probably replace the distributor, since it's the original one. As I was turning the engine over with the starter the gear on the end of the cam was turning, so the timing chain must be OK. My new problem is aligning the rotor. There was no point to marking the rotor location, as the engine had been turning without it. Any suggestions as to how to locate the new distributor to get it in sync with the balancer?


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## Rukee (Feb 8, 2007)

Pull the #1 plug and roll the engine over with your finger over the plug hole, when the compression blows your finger off the hole, stop turning the motor over. Line-up the timing marks on the balancer to 0*, then drop in the distributor so the rotors pointing at #1 plug wire.
Or, pull off the one valve cover and turn the motor over watching the valves till you see the #1 cylinder on the compression stroke, again line up the balancer to 0* and drop in the distributor lined up to #1.
If you use a unit like an MSD ignition box, the stock distributer will work great and won`t need replacing/upgrading. I`d rather see you just replace the roll pin and buy the MSD unit rather then a diffrent distributer. You`ll see more performance increase. Just my 2cents.


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## Rukee (Feb 8, 2007)

Page three of this thread shows how I made a plate to mount and hide the MSD unit behind the fender and inner fender well. Works great and no-one knows it`s there, sept the few hundred people who read the thread. 
http://www.gtoforum.com/f50/trunk-pan-replacement-14451/


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## Alan (Jul 8, 2006)

Hi Ruckee, Here's my plan to realign the distributor: With the distributor out, I keep popping the starter until the mark on the balancer lines up with the usual 6'TDC hashmark. Then I put in the distributor and move it around until the points brush is on a high point on the cam, opening the points. Then I clamp the distributor, put the wire from the #1 plug into whatever spot the rotor is pointing to, then the other plug wires in the firing order from there. Will that work?

About the MSD unit, the Ames catalog shows something called Pertronix electronic ignition system that converts the points distributor. Is this the same thing? If not, can you suggest a good commercial MSD? Thanks again for the good advice.


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## Alan (Jul 8, 2006)

Just to wrap this up, replaced the sheared roller pin in the distributor, put it back together, tuned it up and she's running better than before. Seems nothing else was damaged by the backfires. Thanks especially to Rukee for the good advice, saved me a lot of trouble.


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## Rukee (Feb 8, 2007)

Alan said:


> Just to wrap this up, replaced the sheared roller pin in the distributor, put it back together, tuned it up and she's running better than before. Seems nothing else was damaged by the backfires. Thanks especially to Rukee for the good advice, saved me a lot of trouble.


No problem, any time. Glad it worked out so easy. 




Alan said:


> About the MSD unit, the Ames catalog shows something called Pertronix electronic ignition system that converts the points distributor. Is this the same thing? If not, can you suggest a good commercial MSD? Thanks again for the good advice.


No, you don`t want that. You want an ignition box like this one....
MSD 6AL CD Ignitions: MSD-6420 - summitracing.com
They make a slightly cheaper one without the rev limiter, but I really like the idea of it. If anything should happen, you spit out a drive shaft, or you burn up a clutch or whatever and the RPM`s skyrocket, the built in rev limiter will keep the motor from grenadeing. It takes all the voltage off the points and instead just uses a resistance through them to fire "Multiple Spark Discharge". It fires the plug more then 1 time per compression stroke. It really wakes the ignition. Plus, now with no voltage going through the points, they tend to last almost forever.


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## likethat (Oct 5, 2007)

I use a 6AL, unilight points replacement, and +4 Bosch platinum spark plugs on my 11 to 1 compression 427 67 RS Camaro. I can use 94 oct. gas with out spark knock. It really made a huge change to the engine. I am sure I am getting spark knock that I cant hear. But it doesn't sound like some one is hammering on the pistons now and it's super quite. When I take it to the track I use 100 oct. and when I am going on long cruses I mix about 3 to 1 94+100 oct. SHHH mixing aviation fuel with unleaded :seeya:


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