Shaking at speed

[Notablecarrot3]

Hi guys,

When I drive my bug I get a rough patch between roughly 2500 and 3500 revs (no rev counter sorry). It feels almost like the car's only on 3 cylinders and makes the car shake really badly at about 55mph in 4th.

If I accelerate through this it sits at high revs ok, low revs also are fine.

When I put the clutch down it stops immediately.

Since this problem I have changed both tranny and motor (stock 1200) for various reasons.

I had this shaking problem with my last motor. The only parts I have swapped over from the old one are distributor, coil, leads, carb (31pict), fuel pump and alternator.

I have tried a friend's HT leads and it made no difference.

Any ideas?
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[drscope]

Any chance you also reused the clutch?

Did you use a matched set of bolts to attach the pressure plate to the flywheel? Even a very small difference in those bolt weights can cause a lot of imbalance to the rotating assembly.
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Mother Nature is a Mean Evil Bitch!

[Notablecarrot3]

I reused the clutch mechanism but changed the plate.

I've only had the problem for a few months and before that I had no problem at all so it is something the car has developed...

It feels almost electric to me, it really feels like the car isn't firing on all 4 cylinders at certain revs.
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[JerryMCarter1]

any chance you can get the car on a scope ?
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Experience always triumphs over hearsay and You get to select which theory to believe