Compression & Cam

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FatJake
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Compression & Cam

Post by FatJake » Mon Dec 08, 2014 1:36 am

Is 7.5:1 compression to low to run an Engle W125 cam?

Everything I've read says it likes around 9.5:1. The car has dual Dellortos on it, so it'll get plenty of fuel. Will it be a monster to tune?

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turbobaja
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Re: Compression & Cam

Post by turbobaja » Mon Dec 08, 2014 3:16 pm

Yes and Yes. Although I'm sure it will "run".

Sounds like it was built for boost. Or with Berg mentality.
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FatJake
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Re: Compression & Cam

Post by FatJake » Mon Dec 08, 2014 5:12 pm

turbobaja wrote:... Or with Berg mentality.
That's exactly how my buddy put it together.

Will it just end up being a nightmare to tune and drive? Am I better off ripping it apart and putting something like a 110 in it.

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Re: Compression & Cam

Post by turbobaja » Mon Dec 08, 2014 6:11 pm

I don't have any personal experience tuning a setup like that, but there's got to be some logic to why Berg liked such low CR. I think it was for insurance/safety reasons with our air cooled engines. It certainly wasn't due to cutting edge chamber/piston design :lol: . If this engine is in an off-road Baja it might be just fine and live a long, forgiving life. In a street car I would pull it down and bump up the compression to make use of that cams rpm potential and pick up some response down low.
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Re: Compression & Cam

Post by Leatherneck » Mon Dec 08, 2014 7:33 pm

I'm running the same compression with a 110 cam and sgl Del 45. I am sure you will be able to tune it since they say duals are easier to tune then sgls.

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Re: Compression & Cam

Post by Piledriver » Mon Dec 08, 2014 7:42 pm

Leatherneck wrote:I'm running the same compression with a 110 cam and sgl Del 45. I am sure you will be able to tune it since they say duals are easier to tune then sgls.

Ah, that would explain the sooty plugs and tailpipe.

If you don't have a wideband O2 setup, even borrowed, you are grasping at straws trying to tune it.
Low DCR makes for odd plug readings.

"Modern" fuel additives don't make it any easier, most folks gave up reading plugs (if using pump gas) a decade ago ...still works to some extent on racing gas, but different fuels color plugs differently, and it only means anything for WOT pulls as in drag racing.

7.5:1 static CR is not as far out to lunch with a 110 as it is with a 120, but it's still lower than optimal for a clean running engine.
Without manifold heat you are going to have to jet it on the rich side just so it doesn't fall on its face on a regular basis.
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