Running on 5

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Datsolow
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Running on 5

Unread postby Datsolow » Tue Aug 09, 2016 11:21 am

Hi all . I took her out for another spin unfortunately now seem's to be running lumpy on the number 4 cylinder side. There is also a loud tapping coming from the rocker cover on that side.
I haven't been able to remove this as of yet , hoping maybe a loose rocker not allowing a cylinder to function correctly.
There is a chuff chuff noise coming from carburetor :eek:
Thanks again from uk :helpsos:
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funvairs
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Re: Running on 5

Unread postby funvairs » Tue Aug 09, 2016 3:24 pm

Running on 5 and chuffing thru the intake,the valve is being held open. a loose rocker the valve would be closed all the time. Sounds more like the valve seat fell out.
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Datsolow
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Re: Running on 5

Unread postby Datsolow » Wed Aug 10, 2016 9:28 am

Ooop compression test time
Datsolow
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Re: Running on 5

Unread postby Datsolow » Wed Aug 10, 2016 9:29 am

I didn't realise the valve seats were removable
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bbodie52
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Re: Running on 5

Unread postby bbodie52 » Wed Aug 10, 2016 11:32 am

Datsolow wrote: » Wed Aug 10, 2016 11:29 am
I didn't realise the valve seats were removable

The aluminum cylinder head material could not withstand the stress that must be endured by a valve seat. The steel valve seats are a press fit into the head and are normally not removed, unless severely damaged or if they loosen up over time. Dropping valve seats has become an increasingly common problem with Corvairs over time as they age — particularly in the 140 hp big valve heads. A qualified machine shop can replace a dropped valve seat, and special deep seats can be obtained and fitted to help prevent the problem from recurring.

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The machine shop route with deep seats can be expensive, and if one has loosened there may be further problems in this area in the future with other valves unless a preemptive and expensive head rebuild with a complete set of deep seats is undertaken. A used replacement head may be less-expensive, but a replacement is still an aging used head and could also develop similar problems later. Most heads are about half a century old and have far-exceeded GM engineers' operational time and mileage expectations! Remember that the use of cast aluminum in cylinder heads was a fairly new technology in the 1960's, and the Corvair was marketed as an economy car with limited service life expectations.

Further discussion...
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:link: http://corvaircenter.com/phorum/read.php?1,748499,748649

Bob Helt wrote:Well the suggestions are all over the map. My opinion is to have the one chamber welded up and then install a new seat. Then put it back together and go.......

Sure you could drop another seat sometime...or maybe never. It's an unknown.
I'd say that the crank is undamaged and that the piston is OK to use as is.

FYI, in MO, staking will not help at all and could cause hot spots.

My shop used to use a small hammer and tap all around each seat. From the sounds then, it was possible to determine how well the seat was being retained. Maybe that would work for you too.

:wrench: :idea: :dontknow:
Brad Bodie
Lake Chatuge, North Carolina
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Datsolow
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Re: Running on 5

Unread postby Datsolow » Thu Aug 11, 2016 2:33 pm

Hi thanks for the information , I took a look inside the rocker cover and the suspect cylinder (4) had a bent push rod ! I did the timing and still lumpy. (5)
Can I take head off whilst engine is still in the car?
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bbodie52
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Re: Running on 5

Unread postby bbodie52 » Thu Aug 11, 2016 3:33 pm

If you are going to remove a cylinder head, you should review the shop manual and the procedures below to see what you are getting into. The heads are somewhat difficult to remove with the engine in the car, since you need to get the carburetor mount and manifold to clear the engine compartment perimeter frame. The process of detaching the peripheral items around the perimeter of the engine and partially lowering the rear of the engine to allow the engine head to clear the body when sliding it off of the cylinder barrels and studs can be a pain. When you add doing all of this while lying on your back under the car, getting dirt in your eyes and mouth, and repeatedly dragging yourself back out from under the car to grab another tool you forgot... well I think I prefer just pulling the entire powertrain and working on the engine heads when everything is clear of the car. There just isn't that much more work involved with pulling the powertrain out of the car first.

Others may disagree.

Having one or more experienced assistants with you to help with the project can make things go faster and safer.

Removing Corvair Cylinder Heads
:link: http://www.corvairforum.com/forum/viewtopic.php?f=225&t=4063

LM Corvair Engine Removal — Part 1 and 2




Corvair and Corvair 95 Power Train Removal & Installation.pdf
Corvair and Corvair 95 Power Train Removal & Installation
(3.35 MiB) Downloaded 5 times


:chevy:
Brad Bodie
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Datsolow
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Re: Running on 5

Unread postby Datsolow » Sun Aug 14, 2016 1:20 am

Hi , I've done a compression check and 1=zero2=75psi 3=45psi 4=75psi 5=45psi 6=50psi.
Doesn't look so great how the hell was it running and still runs.
What is a healthy engine meant to read also , where do I go from here?
Thanks Paul
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bbodie52
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Re: Running on 5

Unread postby bbodie52 » Sun Aug 14, 2016 4:42 am

Paul wrote:Hi , I've done a compression check and 1=zero2=75psi 3=45psi 4=75psi 5=45psi 6=50psi.
Doesn't look so great how the hell was it running and still runs.
What is a healthy engine meant to read also , where do I go from here?

Healthy cylinders should read 130 psi each, with a maximum variation of 20 psi between cylinders. Zero is a complete failure (hole in the piston, stuck valve, etc.) If the rest of your readings are accurately measured (following the procedures in the attached shop manual section) at cranking speed with the throttle wide open, etc., then you are looking at worn cylinders and rings, blown head gaskets, worn out or damaged valves, etc. A cylinder leak down test using an air compressor to pressurize each cylinder can help to determine the cause without disassembly, but an engine with such poor readings would certainly require disassembly and overhaul... or replacement with a serviceable engine.

:sad5:
Attachments
1965 Corvair Chassis Shop Manual - SECTION 6 - ENGINE TUNE-UP.pdf
1965 Corvair Chassis Shop Manual - SECTION 6 - ENGINE TUNE-UP
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Brad Bodie
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Datsolow
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Re: Running on 5

Unread postby Datsolow » Mon Jan 09, 2017 4:09 pm

Thanks for info , I've just found a machine shop to cut new seats n valves £350

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