Mike:
First of all, I assume you meant that you are setting the lash to
to 0.012"I/0.014"E and NOT 0.120"I/0.140"E. If I am wrong in this
assumption, then I would say that whoever gave you that recommendation
is a quack, and should be avoided in the future at all costs.
Ahem. so, assuming that the lash is in fact 0.012"/0.014" let's
do a little math. If we assume a stock cam, you added something like
0.020" more lift when switching to the roller rockers. Subtract from
this the increase in the lash settings, and in rough numbers you netted
0.018" more for the intake, and 0.016" more for the exhaust.
These are small numbers. While I would expect that you will
measure a few more HP on a dyno or on your 1/4mi ETs, you will not
notice this in the seat of your pants.
I would guess you picked up about 3 HP at the crank, slightly
less at the rear wheels.
As far as lash settings go, I cannot say for certain what would
be "correct". I know that the looser you set the lash, the weaker
in effect you make your camshaft. My inclination would be to stick with
the stock settings of (memory check!!) 0.010".
If I recalled the stock lash number incorrectly, someone will
straighten me out. Obviously, if I buggered the stock numbers, the above
calculations would be affected as well, so you can completely
blow me off =:-o
Cheers,
Vance
------------------------------
1974 Mimosa Yellow Triumph TR6
Cogito Ergo Zoom
(I think, therefore I go fast)
-----Original Message-----
From: michael lunsford [mailto:mblunsfordsr@yahoo.com]
Sent: Wednesday, December 04, 2002 6:39 AM
To: 6pack@autox.team.net
Subject: Roller Rocker Performance Question
In response to the roller rocker question currently being bandied about on
the list I have the following to add to my previous post: I am currently
running a set of roller rockers that have a 1.55/1 ratio, on an essentially
stock engine with a compression ratio of 9.9 to 1. I have not noticed any
improvement in performance with this setup. I realize the only potential
improvement would be from the change of ratio from the stock 1.46 to 1.55
and the roller versus non roller friction reduction. I got a good deal on a
used set of Goodparts roller rockers and thought I would try them. Before
anyone says anything let me say that I realize that I need a higher
performance (non stock) cam to get the roller rockers to perform well but I
couldn't resist this experiment. I was told by one of our local experts to
set the valve lash at .12 intake and .14 exhaust. What is the concensus of
the list concerning the proper valve lash for this set up?
Mike Lunsford, 1970 TR6
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