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914World.com _ 914World Garage _ 1.7L Cylinder Compression Values

Posted by: rickso71 Jul 1 2005, 08:16 AM

What would be the lbs. cylinder compression for a rebuilt (and never started) 1.7L engine? I'm getting around 90# on three and 70# in 1. Hoping compression will improve after running it a while.

Posted by: echocanyons Jul 1 2005, 09:33 AM

I recently tested mine and I was getting 115-120 all the way around. (unknown milage not a fresh rebuild)

Did you test with the TB open?

Sounds like you tested it cold.

I would be concerned about the large % difference between 70-90

Maybe someone else will chime in...should a fresh rebuild test with normal compression or does it have to be broken in to fully seal?

Posted by: goose2 Jul 1 2005, 10:31 AM

I wouldn't worry too much about absolute values until the engine has been run a bit. A fresh rebuild that is cold, hasn't been run will be tight and slow to spin. Maybe check valve clearances and squirt a teaspoon or so of oil in each hole and try it again. Make sure there's oil in the sump and spin it enough to get oil pressure. (not an expert, but I play one on message boards)

Posted by: lapuwali Jul 1 2005, 11:43 AM

Yes, compression test figures are tricky. A newly rebuilt engine that wasn't broken in SHOULD be a bit leaky, that's what the break-in procedure is for. Measuring cold will also throw off the numbers. In many cases, a compression test will tell you as much about the state of your starter and battery as it will about the state of the rings and valves.