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My snail is bigger!
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Discussion Starter #1
I'm looking to size some custom camshaft grinds. I've been measuring out the stock front-bank camshaft and I've found these specs so far:

(from valve timing figures in the service manual)

Intake gross duration: 248 degrees
Exhaust gross duration: 248 degrees

(from measuring rocker arm ratios and cam lobe heights)

Intake valve lift: approx. 0.270"
Exhaust valve lift: approx. 0.270"

OK and I just checked the rear bank and of course the base circle and lobe heights are the same, but we all know the centerline of the front and rear banks differs by 4 degrees.

If anybody has a more accurate measurement for the valve lifts, please post that info up!
 

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My snail is bigger!
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Discussion Starter #2
Just checked a set of camshafts from a Diamante 6G74 and those have the same lift at least. No idea about the duration, I assume it's also 248. I know the rear bank camshaft on the 6G74 has a different dowel pin location, but it looks like the Mitsu P/N for the front bank camshaft differs from the 6G72. They must have a different centerline, but I bet that's the only difference.
 

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How does the variance in camshafts degrees between the front and rear banks affect forced induction applications?
 

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Discussion Starter #5
How does the variance in camshafts degrees between the front and rear banks affect forced induction applications?
The front bank tends to be more volumetrically efficient in the upper RPM band, and therefore tends to run leaner relative to the rear bank.
 

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Discussion Starter #6

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i thought stock lift was .320 and the stage 1 only played with duration and LSA and stage 2 added intake lift and stage 3 added lift to both. (im personally looking at going with stage 3 specs in my car)
 

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its due to the difference in LSA between the front and rear cams IIRC. those are hard set, so the only way to "fix" it is to get a different set of cams that dont have the different LSAs between front and rear.
 

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Discussion Starter #10
i thought stock lift was .320 and the stage 1 only played with duration and LSA and stage 2 added intake lift and stage 3 added lift to both. (im personally looking at going with stage 3 specs in my car)
There's no way stock lift is 0.320. That would require a rocker arm ratio of like 2:1... which we simply don't have. I can pull up the measurements I took when I get home, but I'm almost positive stock lift is 0.270"

I don't think that's a stretch. That's only a difference of 5/100 of an inch between stage 1 and stock. And I doubt some of RPW's turbo cams would have lower lift than stock. That seems counterproductive, even if the durations are much increased over stock.
 
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