Question regarding engine differences for EM.

[lostboy]

I just picked up a 98hp automatic engine with the head stamping of 3795960. I'm finding a lot of mixed information. I am under the impression that these are 98/102 heads and am wondering what else is specifically different between this engine and the standard 80hp. Camshaft?

Reason I ask is that my right cylinder head has external damage from rodents. The engine runs great and doesnt overheat, but the head is in terrible condition externally. I was going to just swap both heads, but if there is a justifiable reason to swap the entire engine I would consider that move.

Thanks Guys!

[bbodie52]

3795960 — 1961 98 hp 145 CID 9.0:1 Compression Ratio

Manual Choke carburetors (only year). Automatic choke cylinder heads and carburetors were introduced in 1962.

Road Draft Tube (No PCV System). Positive Crankcase Ventilation (PCV) was introduced in 1963.

Engine displacement increased from 145 CID to 164 CID in 1964. Alternators replaced generators in 1965.

The distributor design on the left was introduced in late 1961, and is was found on all 1962-1969 Corvairs.








The link below will provide you with a list of useful websites that are Corvair-related. Some of the links will lead you to an extensive technical library that will allow you to download shop manuals and other technical references in Adobe Reader format at no cost. There is also a link that will help you to locate nearby CORSA (Corvair Society of America) club chapters. While the Corvair Forum can be very helpful as you work on your Corvair, having local friends and contacts in your region who are knowledgeable about the Corvair can also be very helpful. These family-friendly CORSA chapters often offer picnics, group scenic drives, technical training and assistance, car shows, and competition events that can greatly enhance your enjoyment of Corvair ownership. You will also find a list of essential Corvair parts suppliers. Clark's Corvair Parts in Shelburne Falls, MA is the biggest and oldest Corvair supplier in the world. You will find a link that can provide you with a series of videos that amount to a tour of the Clark's Corvair Parts facilities. I think you will be amazed at the quality of the reproduction components they offer — particularly the interior carpeting and re-upholstery items. Parts suppliers such as this truly make our Corvair hobby possible.

Common and Useful Corvair Websites

viewtopic.php?f=225&t=6007

For more powertrain and engine details, see the attached 1961-Chevrolet Corvair GM Heritage Center Specs. The DELCO ROCHESTER - Models H, HV Carburetor Service Manual provides technical details on the various carburetor design modifications that occurred over the years.

[lostboy]

So is the cam profile different in the two engines as well?

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[bbodie52]

What two engines? The only engine horsepower rating associated with the cylinder head casting number 3795960 you listed was 98 hp in 1961. The 1961 Corvair GM Heritage Center Specifications indicate only two hp ratings in 1961 — the 80 hp Turbo-Air and the 98 hp Super Turbo-Air. Those two engines did use different camshafts, and the specs for each are listed on page 20 of the 1961 Corvair GM Heritage Center Specifications. The 102 hp rated engine you mentioned was not introduced to the Corvair lineup until 1962.

In 1962-1963 the 102 hp rating replaced the 98 hp rated engine from 1961. There were two lower hp ratings listed as 80 hp and 84 hp. The 84 hp engine appears to be associated with 1962-63 Monza engines connected to a Powerglide automatic transmission. The 4 hp increase came from a different cylinder head that produced a 9.0:1 compression ratio, while the 80 hp engine only had an 8.0:1 compression ratio. The 80/84 hp camshaft in 1962-63 was the same as the 1961 80 hp camshaft, but the 102 hp camshaft used in 1962-63 appears to have used a slightly different exhaust lobe profile from the 1961 98 hp camshaft, which seems to account for the hp increase from 98 hp to 102 hp. (The 150 hp turbocharged engine introduced in 1962 used the same camshaft as the 102 hp engine).

The cylinder head technical specifications associated with casting no. 3795960 are confirmed by the technical specifications listed on the Clark's Corvair Parts catalog page shown below.

http://www.corvair.com/user-cgi/catalog ... age=TECH-3

[lostboy]

What two engines? The only engine horsepower rating associated with the cylinder head casting number 3795960 you listed was 98 hp in 1961. The 1961 Corvair GM Heritage Center Specifications indicate only two hp ratings in 1961 — the 80 hp Turbo-Air and the 98 hp Super Turbo-Air. Those two engines did use different camshafts, and the specs for each are listed on page 20 of the 1961 Corvair GM Heritage Center Specifications. The 102 hp rated engine you mentioned was not introduced to the Corvair lineup until 1962.

In 1962-1963 the 102 hp rating replaced the 98 hp rated engine from 1961. There were two lower hp ratings listed as 80 hp and 84 hp. The 84 hp engine appears to be associated with 1962-63 Monza engines connected to a Powerglide automatic transmission. The 4 hp increase came from a different cylinder head that produced a 9.0:1 compression ratio, while the 80 hp engine only had an 8.0:1 compression ratio.

The cylinder head technical specifications associated with casting no. 3795960 are confirmed by the technical specifications listed on the Clark's Corvair Parts catalog page shown below.

http://www.corvair.com/user-cgi/catalog ... age=TECH-3

Ok. I was basically inquiring what the difference was between my stock 80hp and the 98 that I have on a stand. As I said I was originally only going to use the heads but if I follow what you posted I think that will yeild me a whopping 4hp increase, but again I would be doing that for the cooling capacity to be restored as my stock 80 heads are externally destroyed.


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[bbodie52]

Ok. I was basically inquiring what the difference was between my stock 80hp and the 98 that I have on a stand. As I said I was originally only going to use the heads but if I follow what you posted I think that will yield me a whopping 4hp increase, but again I would be doing that for the cooling capacity to be restored as my stock 80 heads are externally destroyed.

The 80 hp heads use a 8.0:1 Compression Ratio, while the 1961 98 hp heads and the 1962-1963 102 hp heads provide a 9.0:1 CR. The 102 hp engine power increase came from a slightly different camshaft used in 1962. The different exhaust lobe profile on the 1962 camshaft accounts for the 4 hp increase in 1962.

The 1962 80 hp engine also saw a 4 hp increase (to 84 hp) with a 9.0:1 CR fitted to Monza engines that were tied to Powerglide transmissions.

[lostboy]

Ok. I was basically inquiring what the difference was between my stock 80hp and the 98 that I have on a stand. As I said I was originally only going to use the heads but if I follow what you posted I think that will yield me a whopping 4hp increase, but again I would be doing that for the cooling capacity to be restored as my stock 80 heads are externally destroyed.

The 80 hp heads use a 8.0:1 Compression Ratio, while the 1961 98 hp heads and the 1962-1963 102 hp heads provide a 9.0:1 CR. The 102 hp engine power increase came from a slightly different camshaft used in 1962. The different exhaust lobe profile on the 1962 camshaft accounts for the 4 hp increase in 1962.

The 1962 80 hp engine also saw a 4 hp increase (to 84 hp) with a 9.0:1 CR fitted to Monza engines that were tied to Powerglide transmissions.

Thanks. So basically I can expect something in the range of a 4hp increase if I use these heads.




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