Engine Rebuild

manxvair · Post by **manxvair** » Wed Sep 19, 2012 3:21 am

I got the spare 110hp Corvair engine tore down today, crank & heads off to the machine shop tomorrow.
This is going to replace the 80hp I broke on the Cool Country Nights run. I hope to have it up and running
for the Mojave Road run.

1856 · Post by **1856** » Tue Sep 25, 2012 4:37 am

Mike have you found what broke? We're in the processes of gathering parts and knowledge to complete a vair powered buggy.
MnC

manxvair · Post by **manxvair** » Wed Sep 26, 2012 4:25 am

No I have not tore into the 80hp motor yet to see what failed, This is a spare 110hp I had laying around that I am focusing on for the rebuild. The blown motor had 0 compression in #5, 100psi-cyls 2&4, 125psi-cyls 1,3 & 6. and a little bit of clanging noise.

ManxManiac · Post by **ManxManiac** » Wed Sep 26, 2012 7:23 am

Hey Mike, probably a dropped valve seat in number 5.

When I had my 140hp heads completely rebuilt after losing the intake valve seat in #5, I had "deep seats" installed on both intakes & exhausts. New valve guides, new int. & exh. valves, retainers & keepers! I completely "deflashed" the heads too for better cooling! I even cc'd & polished the combustion chambers! It'll be FUN FUN FUN when I get it back together & installed on Xena!

1856 · Post by **1856** » Wed Sep 26, 2012 7:40 pm

Mike I have read that dropping a valve seat was common in
the Vair power plant. At this point we're researching the rear engine mount ...
Hadley had developed the rear cage frame to carry that load back to the rear shock
mounts ... However after following the blue Vair powered buggy at Cool Country
Nights in the extreme, run as we did at Big Bear a few year ago without any
rear support, he said that he has been running it that way for 15 years without
problems.
Others have say you need to
carry that rear load back to the main frame. What are your thoughts on this? Inquiring
minds want to know…

MnC

ManxManiac · Post by **ManxManiac** » Wed Sep 26, 2012 8:26 pm

IMO... if you are running the Corvair engine with a Corvair transaxle, then you should consider using the rear mount. Though I do know of a couple f/g buggies & several sandrails that run Corvair/Corvair without the rear mount & have never had a problem. The Corvair bellhousing is fairly strong, but it is also fairly thin & I have seen them crack, but not in a f/g buggy or sandrail.

If you are running a regular or a reverse-rotation Corvair engine with a VW transaxle, a rear mount is not necesary, but for some it gives them piece of mind. All of the various brands of Corvair to VW adapters are fairly thick & quite strong, with the exception of the KEP (Kennedy) adapter. It is definately lighter, however, due to their casting method & its design, they are very strong & probably do not need a rear mount too.

There are always exceptions to the rule & if you are going to be jumping your buggy or some other wild & crazy activity, then you should probably install a rear mount.

The Corvair engine in "buggy trim" only weighs about 80 lbs. more than a VW engine.

When I install the 140hp in Xena, I will not use a rear mount, until I finalize the design of the rear bumper/cage. I will probably end up designing one into the rear bumper, just for my piece of mind... you never know when I might want to jump something.
Not sure how much difference it will make, but Xena's transaxle is mounted solid.

ManxManiac · Post by **ManxManiac** » Wed Sep 26, 2012 9:16 pm

Corvairs with the stock thin valve seats have logged hundreds of thousands of miles without ever having a problem with them. Why Chevrolet decided to use the thinner seats, probably equates to the bottom line... money/profit.
In the earlier years, yes Corvairs dropped seats, but not that often, but because of their "bad reputation", when one lost a valve seat, word about it spread like wildfire & I'm sure the bad seat stories got expounded on. Heat & a lean fuel mixture are two of the big problems that cause dropped seats. Usually, after a prolonged hard run & then shutting the engine down without letting it cool off & stabilize a few moments is when most of them happen. Of course the "newest" Corvair engines (1969) are 43 years old & after thousands of heat cycles & leaky "air" cooling systems etc., they are ripe to drop a seat.

Fixing the Corvair heads with deep seats isn't that expensive & if done correctly, they should last the rest of the engine's life & way beyond. One of the best things you can do to a Corvair cylinder head in order to improve cooling (the air flow thru it) is to "deflash" it. Cleaning out the casting flash is fairly easy & doesn't take much effort or time.

If you seal the cooling tin correctly, deflash the heads & make sure the fan belt isn't too tight, the stock Corvair cooling system works quite well.
Mike aka ManxVair has an electric cooling fan on his Corvair & it has worked great for over 10 years, but if you talk to a bunch of the Corvair "guys", they say it doesn't work well enough & will show you actual testing results to back them up. I know of at least 6 Corvair engines in stock Corvairs & buggies running the electric fan setup & none have ever had a problem.

Corvairs are great "old school" power! They are low rpm/high torque engines & their bottom ends are legendary for longevity. You can run them at 4500 rpms all day. I've owned quite a few over the years & all of them ran great & I never had any problems with them.

FulsGld · Post by **FulsGld** » Wed Sep 26, 2012 10:34 pm

Hey;

Figured I'd jump in here since everyone is talking about Dark-Side engines. A couple of years ago we were at Pismo Beach and we sanded the reverse-rotation engine that was in the Turista. It was using oil like crazy. I went ahead and swapped in a stock VW 1600, and have been using it to go places. A couple of weeks ago I started tearing down the reverse-rotation engine. Checked the ring gap on the compression rings on one of the cylinders and it is sitting at about 1/4". The oil control rings just fall right through the barrel. I'm not going to do anything with the bottom-end except check the rod bearings while I'm pulling the rods to change pistons. I'm putting together a list of parts that I'm going to need. Will get them through the Covair Underground in OR. I'll send the heads to a local machinist that has experience with air-cooled stuff. De-flashing the heads sounds like a good idea. I did drop a valve in one of the heads on a 140hp engine that I was running in my sandrail. Never fixed it, but still have it under the bench. Got a $200 quote to fix the damage and replace the 1 seat and valve. This is going to be a fun project.

ManxManiac · Post by **ManxManiac** » Thu Sep 27, 2012 1:15 pm

Hey Gary, how the heck you doin'???
When I bought my Corvair 140hp reverse-rotation engine, it already had a #5 cylinder, intake seat problem. But I adjusted the valves & it sounded pretty good, so I installed it on our Manx for some testing. During the 2nd lap around the block, the #5 cylinder intake valve seat broke in a couple pieces & 1 piece fell into the combustion chamber & messed it up. Since these heads were ported & polished a bit, I decided to completely redo them. I bought all new valves, all new valve springs/retainers/keepers & took everything to a well known Corvair machine shop in the San Diego area. They work on enough Corvair engines, that they have machines setup just for Corvair heads, engine cases etc.
They installed all new bronze valve guides, all new "deep" intake & exhaust valve seats, welded up & repaired #5 combustion chamber. They also back-cut the underside of the valve's heads to lighten them & to increase flow. All combustion chambers were cc'd & polished.
All the parts & labor totaled $605.00 + the cost of driving down to San Diego & back twice.
However, when we went down to pick them up, we stopped at a yardsale & we bought quite a bit of stuff for $100.00 & ended up selling it all for a little over $1500.00. So I figure when it was all said & done, the heads didn't cost me anything, we had lots of FUN FUN FUN during the 2 trips there & we still had money left!!!

My 164 cid Corvair engine, supposedly flywheel dyno'd on a Stuska Dyno... 219.6hp... I'm sure I will find out! It has a Holley 390cfm 4bbl carburetor on it, that was very lean on the primary side & about right on the secondaries. It should run even better now that everything will be back to spec.

ManxManiac · Post by **ManxManiac** » Thu Sep 27, 2012 1:40 pm

Here is a photo of my Corvair engine when I bought it & after I installed it on Xena.
It had been on Craigslist for a little over 2 weeks & a "Buggy Buddy" emailed me about it. Patricia & I drove to Yorba Linda & I ended up only paying $250.00 for it. Brand new Holley carb & new 4bbl intake manifold, new electronic distributor, new 2 piece OTTO oil pan, new Kennedy Stage 1 pressure plate & disc, new K&N air filter, new custom headers w/ SuperTrapp mufflers, new alternator & a heavy duty Crown Corvair to VW adapter. Plus the guy gave me a large IGLOO cooler full of spare parts & Corvair only tools. Yes I was & still am tickled pea green!

FulsGld · Post by **FulsGld** » Thu Sep 27, 2012 5:00 pm

Hey Maniac;

You scored BIG time! Hopefully you'll be impressed with the power and drive ability of your setup. Some folks do not like the 390 4-barrel carb setup due to the long runners, but I've had really good luck with very little to no hesitation when hitting it hard. I've had this setup on both the sandrail and FULSGLD. Looks like you got some nice prices on the work that you had done, and with the original purchase of the engine. I got my RR engine from a fellow in Pocatello, ID that had put this rebuilt engine into a VW bus. His son didn't like it so they put the VW engine back into it. $300 and he met me half way in Boise, ID. Looking forward to getting this thing back into the Turista for next season.

manxvair · Post by **manxvair** » Fri Sep 28, 2012 12:20 am

I wouldn't be surprised to find the issue to be a valve seat, I was pushing it real hard trying to get up a tricky hill with my clutch slipping (vair trans with 31" tires) when it started making noise and missing. It then developed a small, occasional metal type noise on that side, all the spark plugs on that bank were dark and fouled even after installing fresh ones. with valve cover off, valves appear tight and move with crank rotation.

The 80hp and 110hp are not interchangeable(crank/heads) so I'm putting my money in the 110hp.

When I redo the chassis for the buggy I'm going to a vw type 2 trans with a 5:37 r&p so I don't think I will worry about rear engine support. I was also checking out Dave's(blue buggy) installation, I've seen him on the rides before and I know he's not afraid to to challenge his buggy.

My parts arrived from Clarke's today so hope fully I'll get this together in the next week, and then i can diagnose the 80hp issues.

Gary and Mike thanks for a lot of helpful insight into the vair.

FulsGld · Post by **FulsGld** » Fri Sep 28, 2012 5:36 am

Hey Mike;

Did I hear you right? Are you going to swap out the Corvair transaxle for a VW transaxle? Is this a Conferr chassis ManxVair? If it is, won't that be a whole bunch of fabrication? Just wondering...

manxvair · Post by **manxvair** » Sat Sep 29, 2012 4:03 am

Yes Gary I'm going to have a whole new chassis made up by Dave Barrett, this old Conferr chassis has been used hard and has a lot of patched up spots, I just added some supports to the front because the tunnel cracked under the body flange and the front end almost broke off.

Mike

FulsGld · Post by **FulsGld** » Mon Oct 01, 2012 3:41 am

Hey Mike;

Nothing like a Dave Barrett Chassis. When will he be done building it for you? Since you are going to go with a VW transaxle, will you be building a Reverse-Rotation engine? I might be interested in your old chassis when you are done with it. I have a body, but a butchered back half of the chassis.