EM motor versus LM Motor

[jdflight]

Good afternoon

I was wondering if you could point me in the direction to find the differences in the early model and late model engines. I am wanting to build one for my 61 monza and I have a lead on a free early model motor but one of my club members said not to go with the early model motor because I will be limited by the crank. I am wanting to increase horse power to 150 or above and he suggested a late model would be better.

[bbodie52]

Compared to your Early Model 1961 Corvair, Late Model engines (plus 1964 engines) have many advantages, including...

• A longer stroke crankshaft that produces 164 cubic inches, as opposed to 145 cubic inches in 1961-1963 engines.
• Automatic choke (1961 was the only year with a cable actuated manual choke — which was an intermediate step away from the poor design used in 1960).
• A lightweight magnesium cooling fan plus belt guides that all but eliminated the strain on early fan belts that caused frequent fan belt failures.
• A Positive Crankcase Ventilation (PCV) system replaced the road draft tube in 1963. The new system did a much-better job of removing piston blowby contaminants and gases from the crankcase, which prolonged oil life and all-but eliminated crankcase sludge buildup.
• An improved design for the oil cooler that reduced clogging of the air passages for better cooling of the oil.
• An improved distributor design was introduced in 1962.
• GM switched to an alternator in 1965, which gave better performance and reliability over the old obsolete generator design.
• Rochester carburetors received continuous design improvements over the years.
• 140 hp engine was introduced in 1965. It had four carburetors, better-breathing heads with larger valves and larger exhaust ports/exhaust manifolds and dual exhaust. (The camshaft was the same grind used in the 110 hp 2-carburetor engine introduced in 1964). The 110 hp 2-carburetor engine is considered to be one of the best compromises, with high reliability and good performance.

I would also recommend staying away from the 1960 engine, which was only 140 CI and had many design flaws that slipped into production for only one year. Also, the 150/180 hp turbocharged engine should be avoided as a daily driver. It gets poor gas mileage, demands expensive Premium fuel, is difficult to tune and is temperamental. Fun for weekends, but not for regular, frequent use.

Please let us know if you have more questions. Also, many people who browse the Corvair Forum benefit from reading questions from others that are answered on the open forum. The use of Private Messages bypasses that open forum design. Please feel free to post your questions on the open forum for all to read. It has the added benefit of drawing answers from multiple sources, which can provide you with a better choice of more-complete answers and opinions.

I hope that my answer has helped you in deciding how to proceed.