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Old school engine diags- Sun machines. Anything new like that ?

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trjohnnie John Malinick
Mirror Lake, NH, USA   USA
Check the stuff for sale on Craigs list or Ebay. You can find these real cheap for sale as no one can run them any more. For anything 1980 or older,they are great. The secret is being able to read what the scope is saying. I cut my teeth on this stuff back in the early 70s. Teach your self to read an old scope and you'll be a God to your buddies. Set up a car with a scope and a vacuum gauge and you will never have to buy beer again.

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JohnW63 John Williamson
Apple Valley, CA, USA   USA
I've been checking, I'm watching some old , used, Tektronics O scopes and hoping some low cost inductive leads will work. Sounds like you trigger on #1 spark plug wire and have Channel A on the line from the coil to distributor.



Home of the 1969 GT6+ MK II resurrection project
and a sorry looking 1968 GT6+ parts car trying to stay whole.

Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, NV, USA   USA
In reply to # 1572898 by JohnW63 What I like about the old Sun scopes is the trace of all sparks. You can see issues with the shape and size of the spark all at once.

I've got what seems to be a random miss on my Mustang. Changed plug wires, checked for bad plugs, checked for vacuum leaks around the carb, got the Edlebrock carb adjusted by a guy with a Dyno. Just can't get it to run smooth. Can't really tell if it is ignition or fuel caused. Even removed the Pertronix module and put points back in it and swapped to a stock coil. My Dad has an old Sun 1011 , but the scope was not stable, so I'm not sure if it still works properly. I got a PDF of the manual for it and some troubleshooting sheets and schematics.

Sounds like a wobble in the dizzy.

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JohnW63 John Williamson
Apple Valley, CA, USA   USA
Doug,

Brand new , aluminum billet , distributor. AND... the problem didn't go away when I put the stock one back on. Tried with points and a Pertronics set. With and without the "Flame Thrower " coil. Swapped the spark plug wires, too. Well, I had to, because I had a small fire that melted two plug wires, due to spilled brake fluid. Had to change a wire loom, and an air conditioning hose too. Even tried using a laser thermometer on the exhaust manifold, with the theory that the one missing would be a bit cooler.

It could very well be carb related, even though it's a new Edlebrock 4 bbl. I was told a story of one that shipped with loose jets. I just want to see the spark traces to rule out ignition,



Home of the 1969 GT6+ MK II resurrection project
and a sorry looking 1968 GT6+ parts car trying to stay whole.

Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, NV, USA   USA
In reply to # 1585558 by JohnW63 Doug,

Brand new , aluminum billet , distributor. AND... the problem didn't go away when I put the stock one back on. Tried with points and a Pertronics set. With and without the "Flame Thrower " coil. Swapped the spark plug wires, too. Well, I had to, because I had a small fire that melted two plug wires, due to spilled brake fluid. Had to change a wire loom, and an air conditioning hose too. Even tried using a laser thermometer on the exhaust manifold, with the theory that the one missing would be a bit cooler.

It could very well be carb related, even though it's a new Edlebrock 4 bbl. I was told a story of one that shipped with loose jets. I just want to see the spark traces to rule out ignition,

I'd check compression before diving into the carb.

JohnW63 John Williamson
Apple Valley, CA, USA   USA
Doug,

I admit, I have never checked the compression, but that is because it sounds very even, when cranking. I know I should, just to rule it out. It's the first engine I ever rebuilt, so , I could have made a mistake with the rings. I had it on a engine stand since 1999 or so, and got it in the car just 2 years ago, I'd say. Had a kid, and life got in the way. The project started and stopped a few times on the way.



Home of the 1969 GT6+ MK II resurrection project
and a sorry looking 1968 GT6+ parts car trying to stay whole.

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1586257 by JohnW63 Doug,

I admit, I have never checked the compression, but that is because it sounds very even, when cranking. I know I should, just to rule it out. It's the first engine I ever rebuilt, so , I could have made a mistake with the rings. I had it on a engine stand since 1999 or so, and got it in the car just 2 years ago, I'd say. Had a kid, and life got in the way. The project started and stopped a few times on the way.

Checking compression when the motor is freshly assembled and still on the stand is one of the easiest and most effective diagnostics that you can run.
It will reveal early on if there are issues, and there will never be an easier and quicker opportunity to remedy an issue than that point.
Yes, you may still develop issues later on when the motor is actually running under power, but the 20 minutes you spend are a cheap investment.

Carter

JohnW63 John Williamson
Apple Valley, CA, USA   USA
Quote: Checking compression when the motor is freshly assembled and still on the stand is one of the easiest and most effective diagnostics that you can run.

Yeah, if I had 20/20 hindsight, I would have. Not sure how I would have hooked the starter up, since it attaches to the bell housing and would need the flywheel installed, which is where the engine stand attaches.



Home of the 1969 GT6+ MK II resurrection project
and a sorry looking 1968 GT6+ parts car trying to stay whole.

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