Help with engine setup for 110 powerglide

[vairguy63]

An automatic (PG) Corvair needs an engine that develops most of it's power at less than 4,000 RPM. The 110HP engine is a good fit because it develops more power at lower RPM due to:

Longer stroke vs. EM engines
High compression
Smaller valves vs. the 140HP engine (four carbs)

In fact when the 140HP engines was ordered with a PG it was really more like 120HP since the PG version came with a 95HP camshaft that was retarded by a special crank gear to try and flatten the torque curve over a broader RPM range. This was done because the 140HP engine from the manual transmission car just did not work well with a PG.

By today's standards the 110HP PG Corvair is just adequate in modern traffic, but it does the job well. In heavy city traffic it is actually a lot nicer to drive than a manual transmission Corvair.

Just my opinion based on subjective experience.

Appreciate the advice and tips 66vairguy. I don’t want to be penny wise and pound foolish as you said. Was just exploring the option since this will not be a performance build- but don’t want detonation or possible dropped seat for the $5 difference per fill up!

I offered to get him a newer car but he wants nothing to do with them. Probably my fault since I’ve been daily driving classics since before he was born. My oldest son got a ‘63 Spyder for his 1st car and I don’t think that helped either. But he wants the cruiser style of the PG.

Looking fwd to doing this build with him. We’ll upgrade to front discs if possible since I haven’t found any info on a dual master conversion for the ‘60. Also putting seatbelts in her for him and passengers.


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[terribleted]

OK so 91 octane unleaded ethanol mixed fuel is the best you can get? That would be a fine choice in the 110 I described especially if adding .010-.020 head gasket thickness. Here it is rated at 92. If you must run 87 then the 95 heads would be a better choice. Stay small in overbore and stock in camshaft, jet the carbs a couple numbers bigger than stock (51 or 52) and keep the compression at stock or slightly less ( maybe add .010-.020 to the head gasket thickness after compensating for any head gasket seat step machining).

Sounds good terrilbleted. Thanks for the advice and specifics. Sounds like the 91 is a better choice all around. I’ll have to go 30 over on the pistons since the LM barrels I have are .021-23 over now :/

The 110 heads have a thin step now that will need to be machined/flycut to probably remove the step completely to get even surfaces. Should I stack .052 and .032 copper gaskets to get it back to approximate stock squish/quench?


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You might need to stack copper head gaskets? You need to measure or CC to find out. you would need to use thicker than stock .032 thickness for sure to go back to stock. I usually measure and compensate for the thickness lost in machining. When I build one for me I usually add .010 to stock stack to help with ping. You must be careful who does the machine work. Cutting the gasket seats must be referenced properly from the face of the head not the valve cover surface or crooked heads result.

[66vairguy]

Ted had good comments.

Detonation usually doesn't affect seats, it damages pistons. The large valve 140HP heads have more problems with dropped seats vs. the other Corvair engines. Any Corvair engine that is overheated will probably drop a valve seat. Also over revving the engine with stock valve springs causes "valve bounce" that can damage the valve seats.

The shop that did my heads has done Corvair heads for decades. The local Corvair mechanics have used the place for many years. I get new valve guides, valves, springs, and of course deep seats. The shop machines not just the gasket registry (area of head gasket touches), but the chamber step to give a CC value that drops the compression about half a point to deal with today's fuels (I always CC heads that are rebuilt). I run 91 octane premium fuel and have had NO detonation issues with the stock timing.

[vairguy63]

OK so 91 octane unleaded ethanol mixed fuel is the best you can get? That would be a fine choice in the 110 I described especially if adding .010-.020 head gasket thickness. Here it is rated at 92. If you must run 87 then the 95 heads would be a better choice. Stay small in overbore and stock in camshaft, jet the carbs a couple numbers bigger than stock (51 or 52) and keep the compression at stock or slightly less ( maybe add .010-.020 to the head gasket thickness after compensating for any head gasket seat step machining).

Sounds good terrilbleted. Thanks for the advice and specifics. Sounds like the 91 is a better choice all around. I’ll have to go 30 over on the pistons since the LM barrels I have are .021-23 over now :/

The 110 heads have a thin step now that will need to be machined/flycut to probably remove the step completely to get even surfaces. Should I stack .052 and .032 copper gaskets to get it back to approximate stock squish/quench?


Sent from my iPhone using Corvair Forum mobile app

You might need to stack copper head gaskets? You need to measure or CC to find out. you would need to use thicker than stock .032 thickness for sure to go back to stock. I usually measure and compensate for the thickness lost in machining. When I build one for me I usually add .010 to stock stack to help with ping. You must be careful who does the machine work. Cutting the gasket seats must be referenced properly from the face of the head not the valve cover surface or crooked heads result.

I’ve got a good machine shop that’s been doing Corvair work for over 40 years- but not exclusively.

A while back I was doing an engine build for a friend and his heads appeared to be stock/uncut so I measured the step in the chamber at .057. Does that sound right or do you have different specs on that?.


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[vairguy63]

Ted had good comments.

Detonation usually doesn't affect seats, it damages pistons. The large valve 140HP heads have more problems with dropped seats vs. the other Corvair engines. Any Corvair engine that is overheated will probably drop a valve seat. Also over revving the engine with stock valve springs causes "valve bounce" that can damage the valve seats.

The shop that did my heads has done Corvair heads for decades. The local Corvair mechanics have used the place for many years. I get new valve guides, valves, springs, and of course deep seats. The shop machines not just the gasket registry (area of head gasket touches), but the chamber step to give a CC value that drops the compression about half a point to deal with today's fuels (I always CC heads that are rebuilt). I run 91 octane premium fuel and have had NO detonation issues with the stock timing.

Agreed!

I always CC as well and usually don’t find that much variance. But... I just showed my son how to CC heads last night and we did a set of 140 heads someone brought me-already machined- they cc’d at 46.4, 46.8 and 46.4 on one head and on the other... that one varied 47.4, 48.6 and 49.4. The step was nearly gone in both heads and the surface had been machined to remove an equal amount to what they flycut from the step/ gasket surface according to the owner.

Should I remove material from the chamber areas evenly to bring them all to about 49cc or is this variance ok?


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[terribleted]

That thickness of the step is about right. I just measure some on a 140 head the other day that I am sure has not been cut and saw .056-.057 or so.

[vairguy63]

That thickness of the step is about right. I just measure some on a 140 head the other day that I am sure has not been cut and saw .056-.057 or so.

[emoji1360]


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[vairguy63]

Project update... cleaned the XXA case and prepped it according to Bob Helt’s guidelines. Got the ‘65 110 heads back from the machine shop. Have an Otto 10 cam with new Cal Corvairs gear & lifters ready to go. The machine shop pressed new .030 cast pistons onto machined LM rods and matched them to our set of barrels. New Hastings cast rings, and my son is cleaning the front oil housing... let the assembly begin!

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