High compression 205 psi average on all cylinders

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GasDaddy140
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Re: high compression 205 psi up date

Post by GasDaddy140 »

Right-on Tom!
Alan Duquette
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64powerglide
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Re: high compression 205 psi up date

Post by 64powerglide »

Good to hear of the happy ending, now enjoy the ride. :tu:
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azdave
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Re: High compression 205 psi average on all cylinders

Post by azdave »

Awesome you got it figured out!

I merged your recent update to your original thread. In the future, readers will find all that what was done to solve your troubles in one place without having to search multiple threads or missing the new update altogether.
Dave W. from Gilbert, AZ

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bbodie52
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Re: High compression 205 psi average on all cylinders

Post by bbodie52 »

tom becker wrote:Mon Aug 21, 2017 3:52 pm

I'm back with an update on the engine compression. I got my compression lowered to 145# average by adding a thicker head gasket. I also replaced the cam with a Iskenderian 270-HL-HYD grind cam. I got a degree wheel and using .050 lobe lift got the cam on the mark. The engine vacuum is down to 11 inches and steady, I was told with that cam, the vacuum would be lower, but not sure it should be that much. Now to driving. the engine idles good. starting out in low its ok, but when I give it full throttle, the acceleration seems poor as if not getting enough gas. The same for drive, runs ok until you step into it, and some times it cuts out. It just seam it not getting enough fuel. The fuel pump is new and pressure and gas flow was checked out and ok. Do I need to get larger main jets? Not sure what's in there now, but after your comments I will remove the cabs and check them out. Thanks for any help, TOM

Mon Aug 30, 2017 8:54 am
First I would like to thank Corvair Forum and all that those who helped giving me advice on my engine problems. Most of the poorly running engine was do to the distributor. Someone at sometime worked on the distributor, and installed the advance weights and cam assembly in backwards. After correcting the problem the vacuum went from 10" up to about 15" steady, not bad for that 270 cam. I took it for a test drive and WOW it ran great. Thanks to all of you. TOM
I wish that I had picked up on your original description back on August 21, when you first described your problem. I ran into the exact same problem back in 1970 when I finished rebuilding a Corvair engine for a neighbor. When I took the car out on its first test run and stepped on the gas pedal, it felt like somebody had just tossed out an anchor! The car ran fine at idle, but as soon as I tried to apply some power, all of the power evaporated. The harder I tried to push the engine with increased revs, the worse it got. I had no idea what was wrong until I rechecked the ignition timing with the timing light. The timing was spot-on at idle, but I discovered that when I revved the engine the timing mark on the pulley went the wrong direction! Instead of a centrifugal advance, I had a centrifugal retard! As a part of the engine overhaul I had completely disassembled the distributor for a rebuild. That was my first time rebuilding a distributor and since some time had passed between disassembly and reassembly of the distributor, I failed to notice that it was possible to flip the centrifugal advance weights upside down and put them in backwards. It was like creating a little "timing bomb" that was ticking away in the engine unnoticed — until I stepped on the gas. Like all engines, it needed more timing advance. But that is not what was getting!

The problem is an unusual one that most people don't even know is a possibility with the Corvair distributor. Few people disassemble the distributors completely, and even if they do they have at least a 50-50 chance of putting it back together correctly. But when you get it wrong, it becomes all too obvious the first time you try to drive the car!

Centrifugal Advance Weights.jpg
Brad Bodie
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tom becker
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Re: High compression 205 psi average on all cylinders

Post by tom becker »

Thank you Brad for your comments. Now there are two of us in the Corvair world that learned the hard way. I wonder just how many others just gave up. So if the question ever comes up again we will have an answer on where to look. TOM
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