Marcus' Corvair conversion, 914-C6 Options

[r3dplanet]

A few years back I got all excited about doing a Corvair engine conversion for my 1971 car. The project waffled. Numbers were crunched and chewed. Thought and diagrams and opinions were drawn out over long winter evenings.

One particularly rainy winter evening, I found an ad on Craigslist advertising a warehouse full of Corvair parts including engines. So my pal Rory and I drove a hundred miles into the boonies late one rainy night to what turned out to be an unmarked, geographically isolated, former slaughterhouse illuminated by a single 60 watt light bulb. No cell phone reception, no escape. We were met by a couple of toothless brothers who couldn't stop talking about Daddy. Seemingly they only did what Daddy wanted them to do. Daddy wanted them to sell the stash of Corvair parts. Daddy wanted them to steal my Toyota cargo van. Daddy needed to approve the transaction of cash for an engine. Daddy, it turned out, was long dead. The two brothers kept trying to separate Rory and I, and the creepier of the two brothers kept demanding my car keys so he could test drive my van, despite my insistence that it wasn't for sale. For the first time in a long time, I wish I had a tazer gun on me. The brothers eventually showed us exactly what I wanted - an RD code 1965 110HP engine. Fearing for our lives, Rory and I muscled the engine into the van while the brothers went to find more stuff for Daddy to sell to us, or you know, maybe a club or some rope or a ball gag or something.

I left the $100 on the bench and tore the hell out. Rory and I laughed all the way back to town, ever so pleased that we were neither killed, nor raped, nor eaten. Plus, we were one up on a Corvair engine.

So with a provenance like this, and seeing JRust's new car, Dr. Evil's project, and 914coops Nader's Nightmare all take shape I've finally decided to get serious about my own project: the VW-Porsche 914-C6.

The "C" stands for Corvair.

[injunmort]

I don't mean to be obtuse, and I certainly don't know corvair engines but you said the cam runs on the machined aluminum surface of the case without a bearing. did I understand that correctly?

[r3dplanet]

Correct. I have no idea why. Apparently GM engineers didn't think cam bearings were necessary - which seems a bit unsettling. But after finding virtually no wear with the bore gauge, I've come to think that it isn't a huge deal. Apparently, my low wear is near identical to other Corvair engine rebuilds in that the cam journals just don't seem to wear down. One reason I think is that the cam sits so low in the engine that it's constantly flooded with oil. But like you, I certainly raised an eyebrow when I discovered this. Apparently this design decision has been justified over the decades.

I don't mean to be obtuse, and I certainly don't know corvair engines but you said the cam runs on the machined aluminum surface of the case without a bearing. did I understand that correctly?

[DBCooper]

It wasn't just GM engineers, remember who they were looking to for inspiration. Until the mid-sixties VW engines didn't have cam bearings either, the cam rode in the case. Works fine for a couple of hundred thousand miles and then the wear is enough that you can't maintain oil pressure, need either a new case or the old one machined for bearings. Hundreds of thousands (millions?) of engines. So measure the bores well, in every possible location, and especially for roundness.

Oh, and special attention to the thrust surface.

Correct. I have no idea why. Apparently GM engineers didn't think cam bearings were necessary - which seems a bit unsettling. But after finding virtually no wear with the bore gauge, I've come to think that it isn't a huge deal. Apparently, my low wear is near identical to other Corvair engine rebuilds in that the cam journals just don't seem to wear down. One reason I think is that the cam sits so low in the engine that it's constantly flooded with oil. But like you, I certainly raised an eyebrow when I discovered this. Apparently this design decision has been justified over the decades.

I don't mean to be obtuse, and I certainly don't know corvair engines but you said the cam runs on the machined aluminum surface of the case without a bearing. did I understand that correctly?

[McMark]

Porsche did the same thing until the stopped making the cases from aluminum.

It wasn't just GM engineers, remember who they were looking to for inspiration. Until the mid-sixties VW engines didn't have cam bearings either, the cam rode in the case. Works fine for a couple of hundred thousand miles and then the wear is enough that you can't maintain oil pressure, need either a new case or the old one machined for bearings. Hundreds of thousands (millions?) of engines. So measure the bores well, in every possible location, and especially for roundness.

Oh, and special attention to the thrust surface.

Correct. I have no idea why. Apparently GM engineers didn't think cam bearings were necessary - which seems a bit unsettling. But after finding virtually no wear with the bore gauge, I've come to think that it isn't a huge deal. Apparently, my low wear is near identical to other Corvair engine rebuilds in that the cam journals just don't seem to wear down. One reason I think is that the cam sits so low in the engine that it's constantly flooded with oil. But like you, I certainly raised an eyebrow when I discovered this. Apparently this design decision has been justified over the decades.

I don't mean to be obtuse, and I certainly don't know corvair engines but you said the cam runs on the machined aluminum surface of the case without a bearing. did I understand that correctly?