compression test Avanti R1

[long1776]

Made another compression test, using a prof tester. All cylinders 155 except # 2 at 180. Squirted 4 shots of oil into each cylinder, that resulted in 5 cylinders unchanged and 3 cylinders increased 5 - 10.
What I don't know is how much should compression increase if rings were bad? Is 5 - 10 just normal usage for an engine with 85.000 miles? Is 155 normal with thick head gaskets? Why then do I have 180 in one cyl?
Lots of questions!

[Bud]

You may have excessive carbon build up in the cylinders that have the higher compression. If the compression only increases 10 psi with oil added the the lower reading cylinders, that's fine. You could have worn valve guides in the cylinders with the high readings causing oil to be sucked into the cylinder which is then burned. Bud

[long1776]

FYI, a PO installed new valve stem seals, I've also observed that the sparkplugs get sooty quickly. In a previous post I said that the vacuum is between 13,5 - 15, and oscillating.
Perhaps we can rule out rings and , perhaps, say that the heads should be restored, new seats, valves etc. Am I wright or wrong? Any ideas?

[PackardV8]

FWIW, at 85kmi a valve job will always help performance, economy and oil consumption. The CASO method of hand-lapping the old valves and knurling the guides will help for a few thousand miles and is all labor, no parts.

The best and most expensive cure is new valves, guides, hard exhaust seats, positive valve stem seals and surfacing the head.

Bottom line, by most Stude owner standards, your engine ain't broke. First, rebuild the ignition system - new points, condensor, rotor, cap, wires and plugs. Adjust the valves and carb to spec, then drive it for another year while saving money to do it right.

thnx, jack vines

PackardV8

[wcarroll@outrageous.net]

You might want to consider performing a leak down test instead of the compression test.

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