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

[Dr Evil]

There has been lots of interest in the corvair power plant over the years as a possible source of cheap HP for many vehicles. There are used in experimental aviation, dune buggies, buses (such as mine), and in place of many other air cooled VW power plants. They are fairly cheap to buy and build, very easy to build and maintain, and plentiful with readily available parts from several suppliers.

The main divide in the corvair engine line took place in 1965 when the displacement of the engine was moved to 2.7L and was offered in a NA 110HP, NA140HP, turbo 150HP and turbo 180HP. The only differences in the long block between these engines are the nitrided crank found in all but the 110HP, and the heads: 110 had one single barrel on each head, the 140 had 2 with one acting as primary and one as secondary. The turbos had a single barrel blow through setup.

The heads are the major limiting factor in the design. They are not built in an intuitive way and rob much hp. The 140 head had bigger valves, but like its 2.0L TIV analog, would drop valve seats due to the limited amount of material between the seats in the head, and the inability of larger seats to shed heat as well as smaller seats. This can, and has been overcome by those who have been rebuilding these heads fro decades by making sure the crush tolerance on the seats are correct, and staking the seats in place.

Currently, you can get a set of rebuilt, 140hp larger valved heads, with new hardware and no core for about $1200 from Corvair Ranch in Gettysburg, PA. I bought a set that was rebuilt and had the plenums taken off for tri porting for $1500 shipped off of ebay from Starr Cooke in El Cajon, CA, another well known Corvair entity.

Modified with plenum removed for individual runners:


The above uses an adapter that allows the placement of Weber triples. My set came with this adapter.

Here is a head with a stock plenum, modified with bungs for FI. This is a 140 head as it has two carb bases on it:


Standard engine:


One of the cool things that many ACVW folks like is that the corvair engine has stock hydraulic lifters on it that use standard lifter, push rod, and rocker parts from Chevy. Easy and cheap to obtain.

Another great feature that I like over ACVW is the box design on the case. The top and bottom come off and allow for any maintenance. Swapping rods, bearings, what ever, is easy.

[r3dplanet]

One more thing.

Under the heading of "interesting statistics," I found on www.corvair.org that of the 1.7 million Corvairs produced, 1.3 million of them were manufactured from 1960-1964. From 1965-1969, there were 400,000 produced, the bulk of which were born in 1965. Only 6000 were made in 1969. So while it is more difficult to get a 1965-later engine, they're going to be considerably more rare. I think that the 1964 motor, the serious transition year, would also be a good find. It doesn't have quite as meaty material where the head meets the block and the crank hasn't been chemically nitrided, but you can nitride any crank for $50 the last time I looked. The 1964 motor is still 164ci. What you need to make sure of that if you're out sourcing parts and you're buying rebuild kits, make sure that all the manufacturing years line up. 1964 is also a transition year because the later 1964 engines were actually the 1965 engines, but the 1964 engines still had the early style numbering scheme, so it might be pretty difficult to recognize a '64 motor just by the serial number.

I'm posting this to others who might be snooping out engines and may find this information useful.

-marcus