Compression on 420 engine

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PHPaul
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Compression on 420 engine

Post by PHPaul » Tue Nov 12, 2019 8:37 am

What would be considered a decent number for compression on a 420 engine?
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Lavoy
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Re: Compression on 420 engine

Post by Lavoy » Tue Nov 12, 2019 8:40 am

Been a long time since I tested one, but seems to me past 100, in the 120 range.
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PHPaul
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Re: Compression on 420 engine

Post by PHPaul » Tue Nov 12, 2019 10:35 am

Thanks. Getting 60-70 on mine, but it's not spinning very fast. I'll do the usual checks to see if it comes up.
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gregjo1948
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Re: Compression on 420 engine

Post by gregjo1948 » Wed Nov 13, 2019 5:26 am

I'd be surprised if it would even start up with compression that low.
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PHPaul
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Re: Compression on 420 engine

Post by PHPaul » Wed Nov 13, 2019 5:51 am

Starter is pretty tired but starts and runs well. Reasonably sure my gauge is okay, think the low numbers are just because it turns over so slowly.
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Greasy1
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Re: Compression on 420 engine

Post by Greasy1 » Thu Nov 14, 2019 11:25 am

Did you remember to open the throttle plate fully?
Hooked on crawlers when I worked on my first Euclid. Just bought 1957 420c

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