110hp block + 140hp heads

[ossieoz]

I’ve been lucky this weekend and managed to buy a 110hp block that’s 95% complete and looks like it’s been renovated already :)

T0203RH, so it’s a 110hp with PG i believe

I’ve also (in the same purchase) got hold of two 140hp heads (not assembled). The original 110 heads were not there anymore.

I’ve been checking out if it’s possible to put the 140 heads on the 110 block. With all my googling I believe it is possible and not an issue. Just bolt on and drive, so to speak... Or?

I’m actually thinking of using the heads with only two carbs and blocking off the secondaries. This sort of leads me to my next question... I actually would prefer 110 heads on the 110 block and was thinking of seeing if anyone in the Swedish Corvair club has some 110 heads that they would like to swap for my 140 heads. Are 140 heads worth a lot more than 110 heads? I know of course condition is an issue, but if they are in similar condition, what is my position on swap ‘power‘? ;)

Thanks again for any help :)


1961 Greenbrier, 1962 Rampside and 1964 Monza cab.

[bbodie52]

T0203RH is a 1965, 1966, or 1967 110 hp configured for a Powerglide automatic. The 1965-1966 140 hp Corsa engine and the 110 hp Monza engines shared the same camshaft, and essentially the same bottom end. The 140 hp crankshaft was a nitrided crankshaft (advanced heat treating) and can be identified with an Ampersand (&) stamped at the flywheel end. The main difference was the cylinder heads, single muffler exhaust, and only dual carburetors. The compression ratio was the same on both engines, so performance was similar at the low end. The difference became more-apparent when the revs increased and the secondary carburetors opened up, taking full advantage of the larger valves and the dual exhaust in the 140 hp engine.

I pulled the camshaft specifications below from the GM Heritage Center Specifications for the various years. I believe that in 1965 and some later years the 110 hp and 140 hp engines used the same camshaft. Some later 140 hp engines received different camshafts and I believe there was some change in cam timing offset as GM experimented to try to find a combination that would work better as SMOG pumps and other government-mandated emissions standards forced modifications.

Thu Apr 05, 2018 12:47 pm

Brad is basically correct about the 1965 110HP and 140HP cams being the same (#891). There has been discussion that the #891 cam profile was revised slightly to prevent valve bounce around 5,000 RPM during the 1965 model run. Also some claim the late 65 and 66 140HP engines used the turbo cam (# 304). Anyway ---- yes many have bolted 140HP heads onto a 110HP engine without a cam change. Note the 140HP and turbo engines got a nitrided cranksahft and the 110HP did NOT. For limited hobby NORMAL driving it's not an issue. If you are going racing then it is.

Oh - the PG (automatic) 140HP engines got a mild (#889) cam with a special crank gear retarded 4 degrees.

The 140 hp exhaust manifolds have a larger cross-section with larger gaskets for better breathing. Dual exhaust was standard as well, so your 110 hp exhaust system will not fit. The larger valves and enhanced exhaust system were meant to complement the 4x1 carburetor setup with secondary carburetors. If you eliminate the secondaries you will simply run out of airflow at the top end to make full use of the big valve heads at high engine RPM speeds.

The 140 hp heads should be a direct bolt-on for a 1965 or later 110 hp engine. The 1964 110 hp engine was the only exception, as the outside diameter of the cylinder barrels on 1964 engines (cylinder bore into head) was only 3-3/4" in 1961-1964. In 1965 and later this diameter changed to 3-13/16".

[ossieoz]

T0203RH is a 1965, 1966, or 1967 110 hp configured for a Powerglide automatic. The 1965-1966 140 hp Corsa engine and the 110 hp Monza engines shared the same camshaft, and essentially the same bottom end. The 140 hp crankshaft was a nitrided crankshaft (advanced heat treating) and can be identified with an Ampersand (&) stamped at the flywheel end. The main difference was the cylinder heads, single muffler exhaust, and only dual carburetors. The compression ratio was the same on both engines, so performance was similar at the low end. The difference became more-apparent when the revs increased and the secondary carburetors opened up, taking full advantage of the larger valves and the dual exhaust in the 140 hp engine.

I pulled the camshaft specifications below from the GM Heritage Center Specifications for the various years. I believe that in 1965 and some later years the 110 hp and 140 hp engines used the same camshaft. Some later 140 hp engines received different camshafts and I believe there was some change in cam timing offset as GM experimented to try to find a combination that would work better as SMOG pumps and other government-mandated emissions standards forced modifications.

Thu Apr 05, 2018 12:47 pm

Brad is basically correct about the 1965 110HP and 140HP cams being the same (#891). There has been discussion that the #891 cam profile was revised slightly to prevent valve bounce around 5,000 RPM during the 1965 model run. Also some claim the late 65 and 66 140HP engines used the turbo cam (# 304). Anyway ---- yes many have bolted 140HP heads onto a 110HP engine without a cam change. Note the 140HP and turbo engines got a nitrided cranksahft and the 110HP did NOT. For limited hobby NORMAL driving it's not an issue. If you are going racing then it is.

Oh - the PG (automatic) 140HP engines got a mild (#889) cam with a special crank gear retarded 4 degrees.

The 140 hp exhaust manifolds have a larger cross-section with larger gaskets for better breathing. Dual exhaust was standard as well, so your 110 hp exhaust system will not fit. The larger valves and enhanced exhaust system were meant to complement the 4x1 carburetor setup with secondary carburetors. If you eliminate the secondaries you will simply run out of airflow at the top end to make full use of the big valve heads at high engine RPM speeds.

The 140 hp heads should be a direct bolt-on for a 1965 or later 110 hp engine. The 1964 110 hp engine was the only exception, as the outside diameter of the cylinder barrels on 1964 engines (cylinder bore into head) was only 3-3/4" in 1961-1964. In 1965 and later this diameter changed to 3-13/16".

Thanks for the info Brad. So as the 110hp is from 65 it’s a go... :)

Can i sort of assume it’ll be more hp than with 110hp heads then? 120hp maybe?


1961 Greenbrier, 1962 Rampside and 1964 Monza cab.

[bbodie52]

Same camshaft, dual exhaust, same compression ratio, and large valve 140 hp heads should certainly increase performance, even if you limit yourself to only the primary carburetors. Depending on the way you drive and the terrain and roads that you drive frequently on, you may never miss the absence of the secondary carburetors. I suspect that most 140 hp engines spend much of their life operating on only the primaries. If you decide later that you would like to explore an upgrade, you can always add the secondary carburetors, fuel lines and linkage at a later time.

[66vairguy]

Brad covered it.

About the value of 140 heads. Due to the larger valve seat diameter the heads are more prone to "dropping" valve seats vs. the smaller valve 110HP heads. The problem is effectively fixed by installing deeper valve seats, a common rebuild fix and the only one proved effective.

So ---- if the 140HP heads have been rebuilt with deep seats and new valve guides they are worth more than 110HP rebuilt heads. If the 140HP heads have NOT been rebuilt then they are worth far less, at least to me. Also the gasket surface and chamber have to be in good shape. Sometimes the gasket surface is "sunk" if the heads were badly overheated. If a dropped seat breaks up it will do considerable damage to the head (and piston). Over the years I've picked up a few loads of spare parts and I've given away four 140HP heads that were so damaged the cost to weld up and machine was not economically practical.

Just me, but I ALWAYS tear done and inspect an engine no matter what the claim about it's history. The stories I could tell about things done wrong on rebuilds. davemotohead has a even better stories of things done wrong.

[ossieoz]

Thanks for the info Brad and 66vairguy :)

I’ll check the heads and see if they’re fixed or not.


1961 Greenbrier, 1962 Rampside and 1964 Monza cab.