351w rocker arm question

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Oct 12, 2004 | 09:42 AM

camccardell

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351w rocker arm question

Ok, this may sound kinda dumb, but what is rocker arm ratio?

I mean I want to purchase some roller rocker arms for my 74 351w, but there are soo many types to choose from and there are ratios like 1.5 1.6 1.7 etc.]

So I need to find out which ones to get

thanks

Chris

Oct 13, 2004 | 07:16 PM

RLKBOB

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From: Petersburg, MI

You probably want to use 1.6. It's the ratio that the valve is opened vs. how high the cam lifts. If the cam actual lift is .300 and you have a 1.6 rocker arm the valve will open .480 (.300 x 1.6)

Oct 13, 2004 | 07:40 PM

camccardell

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alrighty,

well it's an rv cam with the stock springs on the heads.
machine shop said the stock springs would handle the lift of an rv cam,
and now I got it, bigger ratio = more cam lift, but do I have to worry about the springs binding if I use anything bigger than a 1.6?

Thanks

Chris

Nov 22, 2004 | 08:41 PM

Tombstone

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Joined: Oct 2004

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From: Los Angeles

If I were you I would spring for the new springs. It can be costly to find out you needed them.

You are asking this question as you are looking at buying roller rockers?

When I went for some roller rockers on my 351 heads I needed mill the pedestals down about a 1/4 inch to use screw in studs. I was using some d50e heads

Ultimately...
If you do a dry assembly and spin the crank by hand you will be able to see any bind situation.

Nov 23, 2004 | 08:44 AM

stangboy_82

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Joined: Jul 2003

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From: Aviano AB, Italy

It sounds like you are having machine work done??? easiest thing to do is just go over the combination with the machine shop if they're halfway competent they should be able to give you a good opinion on what will work and what will not or if you get a cam made from at least any of the big cam manufacturer's eg. comp, crane, isky, etc..... then you can buy the cam rocker's spring's and anything else having to do with the setup from them in a set that you know will work and you know will perform with the intended results