SOT: The truth about Corvair engines, Nothing but the facts and experience, please Options

[ClayPerrine]

I'm not convinced that running the R/P backwards would hurt it.
Reversing the brake band/block on first is easy, no need to even disassemble the gearbox.
I don't know if how the bearings are retained in the case would be a problem though,
but the starter appears to be a significant issue.

You also have to consider the thrust loads on both the input and pinion shafts of the 901. Turning in the correct direction, the helical cut gears on the shafts push the input and output shafts in different directions. When you reverse the input rotation, you change the thrust load. That makes the thrust bearings engineered into the transmission irrevelant, and the thrust load happens against surfaces not designed to handle it. It also changes the backlash on the ring and pinion combo. When there is load on the pinion gear, it climbs the ring gear slightly. When you reverse it, it will not climb the ring gear, changing the backlash and affecting both the life of, and the noise from the gearbox.

Yes, it would work. But no, it won't last long. The extra horsepower of the corvair engine, combined with the incorrect thrust loads will make quick work of the transmission.


FYI.. the reason the corvair engine turns backwards is that the corvair gearbox was a modified saginaw 4 speed that had a hollow main shaft so they could put an extra long input shaft through it's middle to connect it to the rear mounted engine. And the differental assembly is a standard 10 bolt diff that was found in everything GM made. So they made the engine turn backwards so they didn't have to make all new gearbox pieces.

[Dr Evil]

9 bolt diff, 6 on early cars.

[carr914]

[VaccaRabite]

This thread is doing nothing for my wants to build a Corvair....

Zach

[RJMII]

This thread is doing nothing for my wants to build a Corvair....

Or for me it would be a corvair powered street/dune buggy. The manxter 2+2.
(IMG:http://www.914world.com/bbs2/uploads_offsite/www.meyersmanx.com-8112-1298569686.1.jpg)

[Tom_T]

How much is the head work? Shop around to the other places that work on these, the prices vary quite a bit. If you have the heads already, Corvair Ranch may be able to beat the locals. $6000 seems high as I did my build for less than that with new VW parts, etc.

Check parts prices against Clark's catalog, then call around and see what you can get for less. Corvair Ranch does beat Clark's prices, most retailers use Clark's as a base and go up from there.

Dr. Evil,

My mistake, I was including the cost of the SDS-EFI two additional throttle Bodies for the FI.

The Motor with Mostly new parts is only around $3,000 and some change.

But that's why I'm making a spread sheet (IMG:style_emoticons/default/biggrin.gif)

Smitty - looking at your sig line about running for Congress in CA 39th Dist. - you do realize I hope, that once anyone Googles for you and finds you on this website, that they'll realize that you're a NARP - Not A "Real" Politician"!!!! (IMG:style_emoticons/default/lol-2.gif)

Best of Luck , then you can make it a Federal Law that ALL cars 30+ years old are exempt from smog checks, extra fees, driving restrictions, etc., be given exclusive HOV lane priveledges, etc., etc.!!!! (IMG:style_emoticons/default/laugh.gif)

Cheers & Luck! (IMG:style_emoticons/default/beerchug.gif)
Tom
///////

[Dr Evil]

This thread is doing nothing for my wants to build a Corvair....

Or for me it would be a corvair powered street/dune buggy. The manxter 2+2.
(IMG:http://www.914world.com/bbs2/uploads_offsite/www.meyersmanx.com-8112-1298569686.1.jpg)

Wow, that is nice.

[Dr Evil]

For those interested in doing this, I have the heads, adapter, and new holley carb for the set up. The heads are already bored for 94mm p/c and are rebuilt with in the last 1500 mi (IMG:style_emoticons/default/smile.gif)

[r3dplanet]

Hi. I've been picking out bits and pieces for a Corvair motor for myself. I've also been making friends with the Corvair crowd over at www.corvaircenter.com. It's a great forum that stays technical and they've seen their share of VW-Porsche conversions.

If anyone wants to read, I've started a post over there (my name is Redstar these days) that might be worth a read from users here. It's a bit political, but its just my opinion. I don't want to inundate them with my own version of 914 theory and politics, so I've kept it on the level. They've got a sweet knowledge base over there. What's interesting to me is that a guy there just sold his Corvair-powered 914 for $7000 just a few weeks ago. They seem to have known about us the whole time.

http://corvaircenter.com/phorum/read.php?1,385181

I've decided not to go with the VW 94mm cylinder/piston setup but instead will seek a 1965-66 140hp motor unless a rebuildable turbo motor falls in my lap. I'm going to do a Corvair conversion slowly, methodically, with many pictures that I'll cross-post here and at the other forum.

Its funny because I thought I would escape an expensive triple-Weber carburetor conversion. Now.. I have doubts.

-marcus

[Don M]

I'm not convinced that running the R/P backwards would hurt it.

this used to be the consensus many years ago when VW/corvair combos were popular in the So Cal sand dunes, even the modest output ones in our group experienced ring and pinion failure on a regular basis, average life expectancy was 4-5 weekends. after some one figured out how to reverse the engine rotation this problem all but disapeared except in all but the most powerful buggies and even then really no more than the VWs of like power levels.

[Smitty911]

How much is the head work? Shop around to the other places that work on these, the prices vary quite a bit. If you have the heads already, Corvair Ranch may be able to beat the locals. $6000 seems high as I did my build for less than that with new VW parts, etc.

Check parts prices against Clark's catalog, then call around and see what you can get for less. Corvair Ranch does beat Clark's prices, most retailers use Clark's as a base and go up from there.

Dr. Evil,

My mistake, I was including the cost of the SDS-EFI two additional throttle Bodies for the FI.

The Motor with Mostly new parts is only around $3,000 and some change.

But that's why I'm making a spread sheet (IMG:style_emoticons/default/biggrin.gif)

Smitty - looking at your sig line about running for Congress in CA 39th Dist. - you do realize I hope, that once anyone Googles for you and finds you on this website, that they'll realize that you're a NARP - Not A "Real" Politician"!!!! (IMG:style_emoticons/default/lol-2.gif)

Best of Luck , then you can make it a Federal Law that ALL cars 30+ years old are exempt from smog checks, extra fees, driving restrictions, etc., be given exclusive HOV lane priveledges, etc., etc.!!!! (IMG:style_emoticons/default/laugh.gif)

Cheers & Luck! (IMG:style_emoticons/default/beerchug.gif)
Tom
///////

No worries Tom, I lost anyway. Seems the people of the district are more intrested in being taken care of than their Personal Freedoms. Oh well.

I should change my sig line, but I'm thinking about 2012. By that time My NARP will be a Air914 (IMG:style_emoticons/default/lol-2.gif)

Smitty

[jk76.914]

We got a new 63 Greenbriar Van - Blue with White stripes & the vinyl houndstooth looking upholstery - which we drove to CA on old 66 (only small bits of I-40 were started then). I think it only had the base 95 hp motor & auto trans (it was ostensibly Mom's DD), but it fried the valves in TX 1/2 way there & we were stuck while the local dealer fixed it (Amarillo IIRC - I was only 10 then, so fuzzy on the details at 58.5! (IMG:style_emoticons/default/blink.gif) ).

Great car, we had 6 small kids (2 - 10 yrs), 2 parents & all slept in the car on the way & every summer trip up to 67 - back from San Diego to Pittsburgh - no AC either! (IMG:style_emoticons/default/blink.gif)

As kids grew, Dad added an Army Surplus stretcher across the 2 back bench seats that folded up against the wall for driving, & open for sleeping. When we grew to 4 teens, Dad moved up to a bigger rig.

Then Dad got a 67 Chevy 3/4 tom pick-up with 327 ci 2 bbl auto trans & towing pkg. with a cab over camper - ahhhh - the luxury, still no AC though!

Those are great memories. Which jogged mine for some more trivia- Corvair trucks had valve rotators to make them last longer (sounds like it didn't help on yours!) and they also had a transmission oil cooler on the powerglide...

Valve rotators??? (IMG:style_emoticons/default/confused24.gif) I have not seen these, any pics?

I installed the tranz cooler on my PG. It was probably over kill, but I figure I like to floor it over mountain passes, in a bread box, in summer so it couldnt hurt. It was hard to find info on the cooler, it is not common and no pics could be found. I had to consult a guru about how to install and such and still no one could tell me which port is in and which is out.

Finally go around to scanning the shop manual page that covers the trans cooler ports on the powerglide cover. Also, found some valve rotator pictures- for sale on eBay of all places!

[Dr Evil]

Dude! You rock. Thanks for the info. You know what, I have seen those rotators on one of my heads (duh). I forgot all about it until you posted that pic. I hope these are not necessary for my bus usage of 140 heads.

Thank you so much.

[Gearhead1432]

I would like to know more about the valve rotator. My understanding so far has been that normaly every time the valve opens it is rotated due to the offset of the rocker in ralation to the valve stem. Don't all engines operate like this?

Looking at the picture it seems like the valve rotator is a sort of two peice valve spring retainer, maybe even a bearing?

Thanks,
Rob

[Gearhead1432]

Another concern would be the weight the rotator adds to each valve. Probably not a good idea for any high performace engine. I can see how it might help in a bus were rpms are limited and load can be high.

-Rob

[jk76.914]

Another concern would be the weight the rotator adds to each valve. Probably not a good idea for any high performace engine. I can see how it might help in a bus were rpms are limited and load can be high.

-Rob

Exactly right. My Googling uncovered articles that indicate the rotators are used in engines that don't rev high, and that spend a lot of time at or near full power in moderate rpm ranges. Like trucks and industrial engines. They are definitely heavier. I saw a number of sources selling "rotator eliminators"- basically spacers to space the spring up higher on engines that have had their thicker rotator removed. Seems lots of Chev impala sites sell these. Could be the 348 Chevy used them? It was originally designed as a truck engine but pressed into service as the first big block car engine in '59. The 409 replaced it in '62, though it was still available in trucks for a few more years.

Picture of a cross section is below, along with a write up... These are not from articles about Corvairs, but similar. Image is of the "positive" type.

I don't believe the side force on the valve tip could overcome the friction due to the valve spring- just not enough torque with the small torque arm it acts through.


Note that the heads, springs, and keepers are the same with rotators as without on Corvair. Only the valves themselves are different. I'm guessing they are longer, and that's how they handled the thicker keeper. I've never actually seen one myself.

[McMark]

I understand the internals would be spinning opposite of their designed intent. But just as a mental exercise:

If you install a 911 transmission in a 914 (type 4, etc) you get 5 'reverse' gears.
If you then install a Corvair motor and spin that transmission backwards, don't you get 5 'forward' gears?

It's still running on the 'backs' of the gears, but wouldn't flipping the diff be counter productive?

I shouldn't post because I'm talking out my ass. Pfffphbbrfft.
But another mental exercise:

In both the 914 and 911, the main gear stack is rotating the same direction. The flipped diff is the diff(erence).
So a 911 tranny in a 914 still has the main stack going the correct direction... Just the diff backwards.
Spin the whole thing backwards and that makes up for the diff diff, but the core stack is now backwards.
So yeah, Corvair motor plus 911 tranny = 5 gears forward and 1 reverse... But after all of this shell game, the core stack is backwards... Which is said to be bad?

If two wrongs makes a right, does a wrong plus a wrong plus a right make everything wrong but actually right because it is anti counter productive? (IMG:style_emoticons/default/blink.gif)

This will make more sense after I have a beer.

I'm glad someone understood what I was trying to say. (IMG:style_emoticons/default/thumb3d.gif)

[Dr Evil]

I got what you are saying, it was just silly (IMG:style_emoticons/default/rolleyes.gif) (IMG:style_emoticons/default/wink.gif)

[Dr Evil]

Another cost comparison:

Nickies for /6 OR /4 $$$$

Nickies for corvair = $1550 to your desired bore size.
http://www.corvairspecialties.com/cylinders.html

[r3dplanet]

Mmmm... Nikasil. Just like the cylinders in my BMW R75/5 engine. Delicious, delicious Nikasil.

As a proud fellow traveler of TEAL, I'm a little put off by this:

"This product makes the Corvair engine more like it's German counterpart, the Porche." PORCHE.

See: http://laughingsquid.com/the-typo-eradicat...nt-league-teal/

Oh, and look what showed up today! It's a 1967 110hp "RD" engine that will be rebuilt as a 140. I found all the reverse rotation parts locally for $300. Turns out, many Corvair folk have the adapter plates and reverse cams and what-not laying about the corners of their garages. Sure its a bit weathered, but it will soon be the subject of a 914world restoration-porn thread.

Total spent so far: $500, including the engine.

-marcus