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Old 06-18-2008, 09:58 AM
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ignition timing and vac advance 239 flathead

engine: 53 ford 239 BA Flathead
Have a question about timing the engine. I've read alot of topics but still don't understand a couple of things.

1. When I changed the points out I set them between .14 to .16 for the breaker gap. I've not understood what setting Vacumme advance means though...I though it was then same as setting the points? am I way off? Also, I'm having a difficult time setting the ignition timing, now my timing light burned out...so I'm really ticked! to advanced turn the distributor counter clockwise right? Also, I've read to set the advance a little high for preformance

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Old 09-30-2008, 06:45 AM
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Your point gap is pretty right. About 15 thou. Vacuum advance means that when there's engine vacuum it sucks on the tube from the manifold & pulls the plate that the points are mounted on, thus bringing the points anticlockwise a bit so as to meet the high lobe on the dizzy shaft a bit early. This has the effect of opening the points early. (Advanced spark) If you lift the cap off the dizzy, and disconnect the little pipe from the dizzy to the manifold and suck on the end of that pipe, you'll see the points plate move anticlockwise a bit. The harder you suck, the further it'll move. (If you're having trouble sucking, I know a young lady who's good at it..???). To set your timing the easist thing to do is to get the No1 piston (that's the front left as you're looking in the engine bay from the front) at Top Dead Centre (TDC). At this point the rotor will be pointing to the No1 lead & you should turn the distributor, ever so slightly until the points are fully open. ie, they're sitting on a high point of a lobe on the shaft. The timing mark should be lined up with the pointer on the crank pully. If the timing mark is lined up ok, but the rotor is pointing at No 6 cylinder, then you're on the exhaust stroke. Rotate the engine one complete revolution till the rotor is lined up with No 1 pot & check that the points are open.

This is static timing, and the engine should start at this point. When it's ticking over, rotate the dizzy anticlockwise (advancing the timing) & the thing should idle faster, until it gets to a point where it starts to buck & slow again. At this point you're too far advanced & the thing won't run & probably won't even start. Take it back clockwise a little till it's idling good.
Take it out on the road and give it a run. If it pings on acceleration, you're too far retarded...not you, your timing!!. Stop, take the dizzy anticlockwise a bit till it will accelerate from a slow speed without pinging.

Also if it spits & farts when you rev the engine (while not moving) it's too far retarded. Advance it a bit at a time till it revs smoothly without baulking.
If that works ok then your timing's not far off. Don't worry about the timing light.
That's how the old blokes did it!!

The pistons number 1 2 3 4 on the right side front to back & 5 6 7 8 on the left side front to back.

I've probably told you things that you already know, but I hope this helps.
Good luck mate.
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