[DeTomaso] Rocker arm ratios

Ken Green kenn_green at yahoo.com
Sat Jul 31 10:14:15 EDT 2010

A lot of the used sets of Jesel rockers are different intake/exahust ratios, like 2.0 and 1.9.  I have no idea why because it seems like they would just grind the intake and exhaust lobes to get the lift and duration, they want,  but maybe the rocker arms ratios have a slightly different affect, or it's just easier to swap rockers arms to adjust the lift?

--- On Fri, 7/30/10, Daniel C Jones <daniel.c.jones2 at gmail.com> wrote:

From: Daniel C Jones <daniel.c.jones2 at gmail.com>
Subject: Re: [DeTomaso] Rocker arm ratios
To: detomaso at realbig.com
Date: Friday, July 30, 2010, 10:21 PM

> Has anyone used different rocker arm ratios to correct for the leaness or
> in  various cylinders in a carburated engine? If so, what was the
I have not.  The usual correction is by stagger jetting the carb and/or
flow bench work on the plenum to equalize the flow into all the cylinders.
We tested shorter rocker ratios on the exhaust side on the 351C dyno
mule and had positive results on the dual pattern cam.  Vizard had
suggested 0.1 to 0.2 shorter ratios on the exhaust side would make
better average power and that was the result we saw.  Vizard once
put O2 sensors (and perhaps thermocouples) in each header tube of
a SBC and found a fair bit of power by stagger jetting, compared to
an optimized even (side-to-side) jetted carb.

Dan Jones

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