Cam timing effects on compression

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datzenmike
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Re: Cam timing effects on compression

Post by datzenmike »

vgwagon wrote:
datzenmike wrote:If 61 degrees should give a cranking compression of 215, and knowing that increasing the closing degree lowers the compression, I assumed that maybe you are advanced one tooth (or 9 degrees). I was hoping that 70 degrees would drop it to 160psi and that would prove to be your problem.... Oh well.

What about retarding the cam a tooth and trying it? Cheap and easy to do. If it improves, maybe try another tooth until power drops off. Then fine tune it closer by advancing/retarding one 4 degree hole on the sprocket. Each hole is almost 1/2 a sprocket tooth.

You expect 160hp? So you are down about 50%... nothing to loose by trying.
That is impressive to make that call over the internet. You are the "L" master zen.
Well thanks Dennis, but don't let Hainz hear you. :mrgreen: I envy you guys building this stuff and running it. I spend way more time thinking about it than actually doing.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs
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defdes
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Re: Cam timing effects on compression

Post by defdes »

datzenmike wrote:
vgwagon wrote:
datzenmike wrote:If 61 degrees should give a cranking compression of 215, and knowing that increasing the closing degree lowers the compression, I assumed that maybe you are advanced one tooth (or 9 degrees). I was hoping that 70 degrees would drop it to 160psi and that would prove to be your problem.... Oh well.

What about retarding the cam a tooth and trying it? Cheap and easy to do. If it improves, maybe try another tooth until power drops off. Then fine tune it closer by advancing/retarding one 4 degree hole on the sprocket. Each hole is almost 1/2 a sprocket tooth.

You expect 160hp? So you are down about 50%... nothing to loose by trying.
That is impressive to make that call over the internet. You are the "L" master zen.
Well thanks Dennis, but don't let Hainz hear you. :mrgreen: I envy you guys building this stuff and running it. I spend way more time thinking about it than actually doing.
That's good, the world needs more thinkers....now get off your brain and start building.
510rob
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Re: Cam timing effects on compression

Post by 510rob »

you guys build it, you guys talk about it, you guys think about it, I just talk shit about it. :mrgreen:

Keith, is that 145WHP, BHP, or AHP?
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bertvorgon
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Re: Cam timing effects on compression

Post by bertvorgon »

That would be on the engine dyno, my assumption was that is what was used, not a chassis dyno. Of course it could be like Rebello's dyno......
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2 Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1971 Vintage 13' BOLER trailer
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defdes
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Re: Cam timing effects on compression

Post by defdes »

The guy I go to has a "Dynapack" chassis dyno, rear wheels come off and are plugged into the machine using splined adapters.
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Yellowcar
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Re: Cam timing effects on compression

Post by Yellowcar »

It's always a nice feeling to get something like that fixed, glad you didn't have to tear the whole motor down. I built a motor for a guy and was trying to figure out why it didn’t run right. Eventually I figured out that the cam had been ground wrong and while the marks all lined up right the timing was actually retarded. I should have degreed the cam rather than relying on the marks…
banzai510(hainz)
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Re: Cam timing effects on compression

Post by banzai510(hainz) »

I say 118 -125hp at the wheel!!!!!!!!!
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defdes
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Re: Cam timing effects on compression

Post by defdes »

:cry: ^^^^^^^^That's cold^^^^^^^^^^^ :cry:
banzai510(hainz)
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Re: Cam timing effects on compression

Post by banzai510(hainz) »

Dereks car had L18 with FI and if I remeber correctly he had 118hp
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bertvorgon
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Re: Cam timing effects on compression

Post by bertvorgon »

I'm going to go with Banzai, on that type of dnyo, maybe even squeek 130 out of it.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2 Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1971 Vintage 13' BOLER trailer
datzenmike
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Re: Cam timing effects on compression

Post by datzenmike »

135-145.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs
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defdes
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Re: Cam timing effects on compression

Post by defdes »

We have a winner!!!!
I actually pulled a 141.3, but I think this was the best overall AF ratio, torque etc..
40 HP and 20 lbs torque costs 5K...now I know.
dyno-1.jpg
dyno-2.jpg
datzenmike
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Re: Cam timing effects on compression

Post by datzenmike »

defdes wrote:We have a winner!!!!
I actually pulled a 141.3, but I think this was the best overall AF ratio, torque etc..
40 HP and 20 lbs torque costs 5K...now I know.
dyno-1.jpg
dyno-2.jpg
datzenmike wrote:135-145.
OH YE OF LITTLE FAITH!
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs
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