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394 Compression Test

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Old May 21, 2012 | 12:19 PM
  #1  
aristellier's Avatar
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394 Compression Test

As my 63 Starfire puffs smoke a bit after idling I'd thought I'd do a compression test just for peace of mind and to make sure there was nothing sinister going on lower down.

I have only managed to do a dry test with the engine warm, the results were as follows:-

1/175, 2/175, 3/155, 4/175, 5/155, 6/165, 7/170, 8/175

Am I right in thinking that these figures are acceptable?

I am going to change the valve stem seals so hopefully this will cure the puffs of smoke.
Old May 21, 2012 | 01:45 PM
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3 and 5 both being low says there may be some issue with head gasket on that side, but overall I'd say your readings are good.

394 are known for valve seal and guide wear and blowby, but if the car runs well and doesn't gulp oil, I'd let it alone. It's probably a good idea to pull the valve covers and rod out the cylinder head drainback holes- if seals/guides are worn and oil isn't draining back to the pan, vacuum will suck it in around the valve stems and cause those annoying little puffs of oil smoke.
Old May 21, 2012 | 01:58 PM
  #3  
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Ditto! If you pull the PCV and the breather while warmed up at idle, do you see a lot of oil smoke, called blowby.
Old May 21, 2012 | 02:10 PM
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Yes I do get the blowby as you describe, My last 63 Dynamic had the same problem.
I'll check what you say about rodding the drain back holes.
Old May 22, 2012 | 12:33 PM
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Would you use something like a bottle brush to rod the drainback holes?
Old May 22, 2012 | 02:21 PM
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A bottle brush will be good, or a metal bristle rifle cleaning brush.

A bent-up wire coathanger always did a bang-up job for me.
Old May 22, 2012 | 11:03 PM
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Cheers.
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