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#2411989 - 12/01/17 06:58 PM Re: Stock 1970 340 T/A Block Compression Test [Re: f2502011]
EV2Bird Offline
No more politics

Registered: 06/23/14
Posts: 4490
Loc: Kansas Roads Between 0 and 140...
Not that id say do it, but every time I see a chevy guy float his valves, his carbon goes out the tail pipes as well.

Robert, most the time we would run them hard to blow the carbon out a good part of that was to clean the carboned up plugs as well.

Id check the plugs and see if they are burnt back and replace if needed.

Heck, you guys already got his rebuild done for him.

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#2412032 - 12/01/17 09:01 PM Re: Stock 1970 340 T/A Block Compression Test [Re: EV2Bird]
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 34396
Loc: Lincoln Nebraska
Quote:
Heck, you guys already got his rebuild done for him.
Hey we're here to help!
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live every 24 hour block of time like it's your last day on earth

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#2412033 - 12/01/17 09:05 PM Re: Stock 1970 340 T/A Block Compression Test [Re: RapidRobert]
amxautox Offline
Still Retired. Still Posting on Moparts. A Lot.

Registered: 05/13/03
Posts: 96645
Loc: On The Boat, On The Lake, Wa. ...
We don't mind spending HIS money. biggrin
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Tom

"Everyone should believe in something; I believe I'll go fishing."

-Henry David Thoreau

Men and fish are alike. They both get into trouble when they open their mouths

author unknown


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#2412075 - 12/01/17 11:16 PM Re: Stock 1970 340 T/A Block Compression Test [Re: dogdays]
f2502011 Offline
enthusiast

Registered: 04/19/12
Posts: 337
Loc: US
Originally Posted By dogdays
Wow, next they'll be telling you to get a borescope!

Those compression numbers from your first legitimate test are low. They are lower than low.

You said there is a lot of carbon in the engine. Last year Hot Rod magazine in one of their "we fix a problem car" articles worked on a mustang and it had low compression in some holes. The mechanic said lets take it out and "blow the carbon out." I always thought that was just a myth. He told the writer that sometimes engines get carbon deposits holding the valve a little open and losing compression.
Go out and get the car warmed up[, do a bunch of hard acceleration runs and some high speed runs. That may help. Get back home and aim the exhaust system away from buildings, people, etc. Remove air filter and with engine running about 2500rpm, trickle some water into one side of the carb. You should get a blast of white steam, maybe carrying with it little chunks of carbon. It's pretty dramatic and will stain a wall or fence. Repeat for the other side. Take it out and run it back up to operating temp and do it again. This may help.

It sure sounds to me like rings aren't working. Try to seat the rings with some sharp acceleration blasts followed by letting the engine pull the car down to speed with throttle closed.

Leakdown tests can tell you the condition of things. If you pressurize a cylinder and air leaks out past the piston the next step is surgery.

R.


The initial and second set of compression results were done with a rental gauge with unknown history from a local auto parts store. The results were questionable. The latest ones were done with the new gauge and were in within spec of > or = 110.

Can rings become unseated? If so how and why?

If I do the leakdown on a warm engine and get good results vs bad results on a cold engine what would that mean?
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1970 EK2 T/A 727

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#2413783 - 12/05/17 05:03 PM Re: Stock 1970 340 T/A Block Compression Test [Re: f2502011]
f2502011 Offline
enthusiast

Registered: 04/19/12
Posts: 337
Loc: US
Did cold leak down today new leak down gauges and got 13.5-14.3% loss at 90PSI. First had to fix my compressor it wouldn’t build pressure and fix a few air hose leaks.
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1970 EK2 T/A 727

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#2413907 - 12/05/17 08:22 PM Re: Stock 1970 340 T/A Block Compression Test [Re: f2502011]
Cab_Burge Offline
I Win

Registered: 08/23/03
Posts: 31673
Loc: Bend,OR USA
Are you going to do a warm or hot test? If not maybe do one cylinder and let us know what you find thumbs
I'm thinking your motor is good based on these results thumbs twocents
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#2413921 - 12/05/17 08:39 PM Re: Stock 1970 340 T/A Block Compression Test [Re: Cab_Burge]
f2502011 Offline
enthusiast

Registered: 04/19/12
Posts: 337
Loc: US
Originally Posted By Cab_Burge
Are you going to do a warm or hot test? If not maybe do one cylinder and let us know what you find thumbs
I'm thinking your motor is good based on these results thumbs twocents


Probably not based on the latest results.
_________________________
1970 EK2 T/A 727

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#2413928 - 12/05/17 08:48 PM Re: Stock 1970 340 T/A Block Compression Test [Re: f2502011]
NANKET Offline
master

Registered: 12/13/03
Posts: 4260
Loc: northwest USA
What is the problem with this car? What are you trying to solve? Does it run correctly?

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#2413950 - 12/05/17 09:17 PM Re: Stock 1970 340 T/A Block Compression Test [Re: NANKET]
f2502011 Offline
enthusiast

Registered: 04/19/12
Posts: 337
Loc: US
Originally Posted By NANKET
What is the problem with this car? What are you trying to solve? Does it run correctly?


Not sure there is one just trying to figure that out by testing.
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1970 EK2 T/A 727

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