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Got my cam today...a bit confused!

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Old 07-16-2003, 10:38 PM
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Default Got my cam today...a bit confused!

I ordered my cam from TSP, but its a custom comp ground cam.

The specs I wanted were 230/224 .575/.563 111LSA

On my cam card, this is what it says

(typed out) Gross Valve lift .588/.584 but written in PEN it says "with a 1.75:1 rocker"

What does that mean, I'm confused, any help would be FANTASTIC! TIA

Btw, everything else is correct.
Old 07-16-2003, 10:50 PM
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Default Re: Got my cam today...a bit confused!

well, your cam actually only has like .340" of lift, however, the rocker arms "multiply" the lift and that is how you get "valve lift", which is quoted on the cam card.

So, if they were speccing it out with 1.75 rockers, the lift numbers will read higher.

What's all this mean to you?

Well, .588/.584 divided by 1.75 rockers is a cam with .336/.334 lobe lift. Now, stock LS1 rocker ratio is right around 1.7:1, so, multiply those 2 numbers by 1.7 and you get .571/.567 which is pretty close to the .575/.563 numbers you ordered.

Does that make sense?
Old 07-16-2003, 10:51 PM
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Default Re: Got my cam today...a bit confused!

Yes it does, thanks for the interpretation!
Old 07-18-2003, 11:39 AM
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Default Re: Got my cam today...a bit confused!

I didnt know they made 1.75:1 rockers for our cars? If so, who makes them, and where can you buy them?
Old 07-18-2003, 02:42 PM
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Default Re: Got my cam today...a bit confused!

well, your cam actually only has like .340" of lift, however, the rocker arms "multiply" the lift and that is how you get "valve lift", which is quoted on the cam card.

So, if they were speccing it out with 1.75 rockers, the lift numbers will read higher.

What's all this mean to you?

Well, .588/.584 divided by 1.75 rockers is a cam with .336/.334 lobe lift. Now, stock LS1 rocker ratio is right around 1.7:1, so, multiply those 2 numbers by 1.7 and you get .571/.567 which is pretty close to the .575/.563 numbers you ordered.

Does that make sense?
That's interesting to learn. I thought grinding camshafts was an exact science. Learn something new everyday, I suppose.

What kind of performance difference would one see between the two lifts mentioned above?

Josh
Old 07-18-2003, 03:00 PM
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Default Re: Got my cam today...a bit confused!

SDPC sells 1.7, 1.75, and 1.8 rockers for our vehicles. They are shaft mount rockers as well...really nice pieces. Check them out here:

http://www.sdpc2000.com/cart.asp?act...amp;catid=3082
Old 07-18-2003, 03:29 PM
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Default Re: Got my cam today...a bit confused!

Nice! I just might have to invest in those for my next mod! I havent had any needle bearing failures yet, but with 68k miles and over 400 RWHP, I don't want to start!




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