140 Compression question

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140 Compression question

Postby 71GTKammback » Mon Oct 05, 2015 2:31 pm

Hey 140 guys,

I am just about to pull the 140 on my 71 Kammback. Been in the car since new. Not sleeved. Numbers matching engine.

Ahead of the sleeve job / rebuild I did a compression check.

1=158. 2=159. 3=162. 4=153.

After squirting some oil in each cylinder

1=161. 2=159. 2=162. 4=158.

Carb wide open all plugs were removed for the testing. Motor about 150 degrees.

Motor smokes and goes through about a quart of 30 weight every 50 miles. Runs perfectly and strong.

Plugs 1, 2 & 3 were all black on the tips. Plug 4 had a whiter color.

Questions... What is a normal compression for a stock 140?

I probably won't have any luck but was hoping to locate something better than 8.5 to 1 pistons. I have 3 sleeve kits but they are all stock 8.5 to 1.

Any thoughts?

Thanks George
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Re: 140 Compression question

Postby kgroombr » Mon Oct 05, 2015 7:14 pm

The cylinders/pistons/rings may be OK. Vega's are known for valve seals to leak like sieve and cause oil burning.

Ken
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Re: 140 Compression question

Postby Monza Harry » Tue Oct 06, 2015 12:24 am

Those seem pretty even across the board. I would also check ring end gap alignment, as well as the valve train as Ken had mentioned. Something comes to mind from my High School years, a friend of mine had a Vega notch that fogged the whole neighbourhood as he drove through, he claimed that the rings had aligned themselves and one was frozen in the grooves. That does mean a complete teardown though. Harry
I'm not a hoarder I'm a preservationist 78 Monza Spyder (~Soon(ish +/- I guess) To Be 2+2 with Spoilers)
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Re: 140 Compression question

Postby 283vega » Tue Oct 06, 2015 7:15 am

I had a vega thirty years ago that burned a quart every tank.I pulled the head and had a valve job done . They knurled the guides and the oil use went to a quart every 2000 miles
283 vega
70 corvette


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Re: 140 Compression question

Postby hammerdown7 » Tue Oct 06, 2015 7:49 am

kgroombr wrote:The cylinders/pistons/rings may be OK. Vega's are known for valve seals to leak like sieve and cause oil burning.

Ken


This sounds like the best bet to me.

Dick
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