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compression
Posted by: vairygood ()
Date: March 14, 2017 12:10PM

Is this something I need to worry about? It is rather unusual I think.
#1...160,#2...120,#3...170,#4...120,#5...170,#6...125.
I am open for ideas.I replaced the lifters,1/2 turn after slight clatter.Runs smooth.
Thanks in advance.
Buster

Buster Tindel
Gulfport Mississippi
63 vert
65 Corsa 140 4 speed

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Re: compression
Posted by: jcorvair ()
Date: March 14, 2017 12:31PM

Yes, seems odd that the left side is that much lower than the right side. Are those results dry or with some oil in the chambers?

What do you know about the engine and heads?

James
Maple Ridge, BC

2013 Hyundai Santa Fe Turbo
2013 Hyundai Elantra (daughter's future car)
2009 Silverado HD Crew Cab 4x4 (for haulin cars, trailers, fifth wheels, quads, etc.)
2013 Victory Car Hauler (enclosed)
2015 Polaris 570 EPS
2016 Polaris 570 SP

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Re: compression
Posted by: MattNall ()
Date: March 14, 2017 12:55PM

Are you sure the Combustion chambers are identical on all 6?





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: compression
Posted by: vairygood ()
Date: March 14, 2017 01:04PM

As far as I can determine the drive train is orginal,heads,block,trans. to the car.I have never had the heads off. The readings were taken after being ran for 30 min.

Buster Tindel
Gulfport Mississippi
63 vert
65 Corsa 140 4 speed



Edited 1 time(s). Last edit at 03/14/2017 01:06PM by vairygood.

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Re: compression
Posted by: MattNall ()
Date: March 14, 2017 01:20PM

one head could've been changed...

One head may have 2 head gaskets..

All you can do is pull them.





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: compression
Posted by: gnvair ()
Date: March 14, 2017 01:32PM

I have seen engines running rich on one bank that would cause similar situation as the additional fuel can wash the cylinders.
The numbers you posted are very consistent on both banks.
I would try checking the tune on it and making sure that you don't have any vacuum leaks.

Lee J

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Re: compression
Posted by: red64vair ()
Date: March 14, 2017 01:43PM

Buster

Have previous compression test indicated the same or is this the first test on this engine?

Larry Blaylock
Saltillo, Mississippi
64 convertible
66 customized Corsa coupe


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Re: compression
Posted by: vairygood ()
Date: March 14, 2017 01:51PM

Larry,this is the first time I have dobe a compression check,I just did a test drive and I have a bad miss,I came back and let it idle in gear(wheels chocked and parking brake on)I pulled one wire at a time and it seems to stumble worse when I pull the right bank wires,not so much when its the left bank.timing is good and so is dwell.Its like no fuel to left bank,that's what I'll look at next.

Buster Tindel
Gulfport Mississippi
63 vert
65 Corsa 140 4 speed

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Re: compression
Posted by: vairygood ()
Date: March 14, 2017 01:54PM

Matt,No I'm not sure about the chambers.

Buster Tindel
Gulfport Mississippi
63 vert
65 Corsa 140 4 speed

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Re: compression
Posted by: Timothy Shortle ()
Date: March 14, 2017 03:58PM

Are you sure this is a concern? If the car runs well (it should with these readings) then drive it.

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Re: compression
Posted by: vairygood ()
Date: March 14, 2017 04:24PM

Tim,no,I'm not sure this is a concern,thats why I asked the question.If I can find the miss then I'll know more,if it has nothing to do with the compression then I'll just drive it as usual I guess.

Buster Tindel
Gulfport Mississippi
63 vert
65 Corsa 140 4 speed

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Re: compression
Posted by: BobV66Vair ()
Date: March 14, 2017 04:29PM

Has a leak-down test been done? You might find one bank leaks a lot. Then do the wet tests to narrow down the issue. May still have to pull the head to investigate. A vacuum leak will be easy enough to fix but not most of the things that may be wrong. Then, of course, you will run into the "mightaswell" issue and do the entire engine.

Bob Vinnacombe
Sandy, Oregon
1965 Corsa 140 stock
1966 Monza Soon to be race car
1968 Monza Parts for now

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Re: compression
Posted by: vairygood ()
Date: March 14, 2017 05:06PM

As crazy as it is none of the cyl leaked down,I let the compression set for 3 minutes on each one and no drop

Buster Tindel
Gulfport Mississippi
63 vert
65 Corsa 140 4 speed

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Re: compression
Posted by: MattNall ()
Date: March 14, 2017 05:10PM

Different heads, or different gaskets...





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: compression
Posted by: BobV66Vair ()
Date: March 14, 2017 05:19PM

MattNall Wrote:
-------------------------------------------------------
> Different heads, or different gaskets...


X2. You may drive it but the stress on the crank and other parts will eventually show. Kind of like an out of balance crank but milder. I would pull that head, find the cause and make sure I would get the same compression on both sides.

Bob Vinnacombe
Sandy, Oregon
1965 Corsa 140 stock
1966 Monza Soon to be race car
1968 Monza Parts for now

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Re: compression
Posted by: Lane66m ()
Date: March 14, 2017 07:19PM

Just curious, was the left carb held wide open for the test?

Al Lane
Ellabell GA

1966 Monza Coupe, 110 hp, 4 Spd
1966 Corsa Turbo Coupe, 180 hp 4 Spd
1964 Greenbrier Deluxe, 6 dr, 80 hp car engine, PG
2015 Chevrolet Malibu 2LT
2015 GMC Sierra SLT Crew Cab
1968 Camaro SS Coupe 350 CI 295+ HP PG
1947 Farmall A tractor 15 hp


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Re: compression
Posted by: vairsUPnorth ()
Date: March 14, 2017 08:47PM

If a repeat of the compression test has a similar result [after making sure that both carbs are fully open, some oil for sealing, etc.] try to find the head numbers before taking anything apart. If the numbers are the same, then something is different about the assembly of the engine on each side. If the heads are different, then you most likely will be in search of a head to match the higher compression side, unless of course, you want to go for lower compression to run on low octane fuel.

[corvaircenter.com]
Dale Dewald
Hancock, MI

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Re: compression
Posted by: JimBrandberg ()
Date: March 15, 2017 04:43AM

How about more carbon build up on one side from running rich?
You don't say what engine you have, 8/1 or 9/1 compression ratio.
Either one, 120 is sort of low but whether it's low enough to "go in" is not an easy decision.
Just shooting from the hip, I'd say one side is low and the other side is high, I might expect 150 or so. That's just a very broad general statement.
Sometimes I do the Seafoam down the carburetor choking smoke treatment if I suspect carbon.
I agree it would be good to identify both head numbers for a start. A lot can happen in 50 years.
Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: compression
Posted by: vairygood ()
Date: March 18, 2017 05:19PM

I'm not going to try and understand but after doing a lot of checking,heads are the same,I did another check(WOT again) and came up with 160 and 170 compression on the left bank,runs smooth again andno problem on acceleration.Go figure lol.
Thanks for all the input,never to old to learn.
Buster

Buster Tindel
Gulfport Mississippi
63 vert
65 Corsa 140 4 speed

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Re: compression
Posted by: jjohnsonjo ()
Date: March 18, 2017 05:24PM

Are both chokes blocked open as well?

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

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