Engine Rebuild

manxvair · Post by **manxvair** » Mon Oct 01, 2012 3:26 pm

Yes I'll be going reverse rotation. I won't be able to start the chassis project until I finish her towd (some time next year) I'll let you when the conferr chassis is available.

manxvair · Post by **manxvair** » Wed Oct 03, 2012 2:47 am

Ok the verdict is in, #5 intake seat went to junk, piston hit it and metal shaving's in cylinders 1 & 3.

CairoManx · Post by **CairoManx** » Wed Oct 03, 2012 9:53 pm

When
the Corvair engine is used in aircraft, its normally only mounted at
one end of the crankcase (with dynafocal mounts) with no problem. The
engine crankcase is definitely capable of supporting itself and in an
aerobatic aircraft, it will support the weight of the entire aircraft
when its hanging from the prop.

What you should probably add are
"torque bars" to strengthen the frame horns which are relatively weak
and are often bent with just VW engines.

Dropping
valve seats was mostly a problem on the 140hp engines which had larger
ports and so less "meat" in the head structure surrounding the seats.
The valve seats are usually OK in a 110hp engine and usually eventually
drop in a 140hp engine, but there's always exceptions like on your 80hp engine.

Deflashing

a head is absolutely essential if you
want it to run as cool as it can. Clark's has "How to Keep Your Corvair
Alive" for just $17 and its filled with info on making the Corvair
reliable. If you have a Corvair engine, its a great read cover to cover.
I think the success of electric fans on a Corvair says more about its
inherent strength and resilience than the effectiveness of the fan. I
don't think there's any doubt that it would increase CHT.

1856 · Post by **1856** » Thu Oct 04, 2012 4:20 am

Thanks that is great information and suggestions. I'll work that way ...

Mark

ManxManiac · Post by **ManxManiac** » Sat Oct 06, 2012 4:05 am

AHA... just as I suspected, a dropped seat.

All horsepower ratings of stock Corvair heads have been guilty of dropped valve seats. However, the stock 140hp heads seem to have the problem most frequently. There is a lot less aluminum where the seats are installed on the 140 heads, but having "deep seats" installed, along with a few other "attention to detail" items, has pretty much cured the problem.
The 80hp, 95hp, 102hp, 110hp, 150hp & the 180hp turbo heads aren't as bad, but they can & do drop seats too.

"De-flashing" the Corvair cylinder heads, has been proven time & time again, to be one of the best & most important things to do to the heads. When GM or their "low bidder" made the Corvair cylinder heads, I guess they never cleaned the molds & the result was lots of "casting flash". On some of the heads it greatly reduces the airflow thru the heads, causing them to run hotter, which is a enemy of the valve seats. I know of Corvair heads that ran fairly high cylinder head temps & after a good de-flashing, the head temps dropped dramatically by almost 50%!
The Corvair's "air cooling system" actually works real well, of course the engine's "life blood", it's oil, is a big part of cooling too!

Unlike VW heads, there are not any aftermarket manufacturers making new ones for the Corvair. Ever now & then, a NOS set comes along on Ebay or some other selling venue, but they usually end up going for a crazy amount of money! Bad part is, they still have the thin seats. The newest Corvair "used" head is 43 years old, so I guess after living that many years they have a right to drop seats!

One procedure that has been done over the years to Corvair valve seats is to "stake" them. A special tool that looks sort of like a dull chisel or a center punch, is driven into the aluminum around the seat, so the aluminum is squished/squeezed/tightened up against the outside edge of the valve seat, thereby helping to hold it in place. Some folks do not like this method, as they feel it will create "hot spots", causing pre-detonation/pinging, even with conservative timing settings.
Another procedure is too actually drill thru the aluminum around the seat & making a small indent on the outside of the valve seat. The hole is threaded & a small set screw is installed & tightened, using a high temp thread sealer, to help it stay in place. I've only seen a few of these, but they seem to be working fine, as one guy has almost a 150,000 miles on his Corvair engine & it still runs great!

One key thing on Corvairs or any engine for that matter, is to make sure the cooling system is sealed up properly, the oil cooler fins are clean & you keep the engine serviced, tuned up & running as proficiently as possible. You will greatly increase its longevity & the amount of FUN FUN FUN you will have for a very long time!

manxvair · Post by **manxvair** » Thu Dec 13, 2012 5:24 am

Ok I got the engine all done and dialed in for now.

[youtube]https://www.youtube.com/watch?v=T2ck4j76tbE[/youtube]

FulsGld · Post by **FulsGld** » Thu Dec 13, 2012 5:35 am

Hey;

Can't get the video to play cause it says it's private. Would sure like to see it...

Ed-Chenal · Post by **Ed-Chenal** » Thu Dec 13, 2012 5:50 am

Same here.....

manxvair · Post by **manxvair** » Fri Dec 14, 2012 1:35 am

Sorry, I made it "public" please try again, 1st time sharing a video clip(obviously)

Ed-Chenal · Post by **Ed-Chenal** » Fri Dec 14, 2012 5:30 am

Sounds good Mike....

manxvair · Post by **manxvair** » Fri Dec 14, 2012 5:43 am

Thanks Ed, It sounds the best it ever has, and runs like never before!

FulsGld · Post by **FulsGld** » Sat Dec 15, 2012 1:31 am

Hey Mike;

Interesting alternator setup. Is that a kit from someplace or homemade? What are you using to drive the cooling fan? Is that electric? If it is, is it thermostatically controlled? Is there a remote oil filter on it?

manxvair · Post by **manxvair** » Sat Dec 15, 2012 7:45 pm

Hey Gary,
It's a homemade kit fabbed by a buddy of mine 15+ years ago. Fan is electric always on with the ignition, oil filter is stock without the 90* adapter.