1963 Corvair Engine detonation

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edherba
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Joined: Mon Apr 29, 2019 9:08 am

Re: 1963 Corvair Engine detonation

Post by edherba »

Yes, 255F is oil temp.
I did not machine the head where the gasket seats. But over the past 50 years, maybe someone else did. How do I know? Can I measure the head gasket seat depth? What should it be?

edherba
Posts: 30
Joined: Mon Apr 29, 2019 9:08 am

Re: 1963 Corvair Engine detonation

Post by edherba »

From Clarks Corvair page 7: "Solid copper head gaskets, reuseable for standard bore thru 3½” (a must on +.030 or larger bores to avoid gasket “hang-over”). Can also be used to adjust for cylinder head resurfacing and lowering compression for running on regular gas. Stock thickness is approximately .032 (so .042 gains .010 and .052 gains .020). 2 Big Bore gaskets can be stacked to adjust for resurfacing. The stock distance from the head surface to the head gasket surface is approximately 0.570-0.580. CHECK TO SEE IF YOURS HAS BEEN RESURFACED".
These head gasket thicknesses are before they are compressed?

edherba
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Joined: Mon Apr 29, 2019 9:08 am

Re: 1963 Corvair Engine detonation

Post by edherba »

I bought some octane booster and put the whole bottle in a full tank of gas. The detonation was greatly reduced and would only be heard slightly when accelerating hard from stop. Oil temp is still a concern at around 255F after 15 minutes of driving in town. I may try swapping the carb jets from #51 to #53. See if that cools it down a bit. Plugs looked normal with the #51. I am on the verge of taking the heads off and installing the copper 0.052" head gaskets. My current compression varies between 160 and 180 depending on cylinder. Should I put the thicker gaskets?

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flat6_musik
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Location: Hesperia, CA

Re: 1963 Corvair Engine detonation

Post by flat6_musik »

That one thing that concerns me is that you mentioned the oil puddling in one of the cylinders, also the deposits around the outer circle of the spark plugs. I hope this motor doesn't have any oil consumption issues, because that will be an instant path to increased detonation, guaranteed.

Have you noticed oil consumption that's above normal?

edherba
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Joined: Mon Apr 29, 2019 9:08 am

Re: 1963 Corvair Engine detonation

Post by edherba »

No oil consumption issues that I noticed. Puddling in cyl 5 is because car is parked on a floor with a slope towards the floor drain and that cyl is the lowest point. I'll keep an eye on that though.

edherba
Posts: 30
Joined: Mon Apr 29, 2019 9:08 am

Re: 1963 Corvair Engine detonation

Post by edherba »

So I redid the compression test with another compression gauge just to eliminate the possibility that my gauge is wrong. It showed compression between 170 and 185 psi. When I checked again with my tester I got 175-190psi. This is done cold. So I guess it confirms that my compression is definitely high. How thick of a head gasket should I use to get the compression down to around 150psi ? Should I go straight away with the 0.052" (0.020" thicker than stock).

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terribleted
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Re: 1963 Corvair Engine detonation

Post by terribleted »

You should measure to see what thickness is needed to return to stock dimensions.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia

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