the lifter bore in the block is too short for roller rockers. whent he factory
tr8
(group 44) ran, they used roller lifters but with a radical cam/lifter design.
the lifter fit down over the cam lobe and the roller was recessed into the
lifter.
worked well on a race car but not a good street application. the street car
doesn't
come apart after every event like a race engine so the cost factor would be very
significant. ted
Susan and John Roper wrote:
> Paul, I have recently been sniffing around in the area of roller lifters and
>am
> told by people that I trust that the lifter bores are too short to allow use
>of
> currently available roller lifters. Tell us about the aftermarket heads that
> are available. John
>
> Paul Rakich wrote:
>
> > Hi List members
> >
> > I've been scouring this list for some time now and have found that it
> > contains very little information (if any!) relating to hydraulic roller cams
> > that can be used with the Buick/Rover alloy V8 (or its derivatives). This
> > seems a little strange (if they are, in fact available), as I would suspect
> > that this is definately an area that would be of concern to the performance
> > enhancement for these engines - especially the bigger capacity variants of
> > these motors that are close to 5.0L. High flow heads for these motors are
> > horrendously expensive (approx. $2000.00 in Oz anyway) and there aren't too
> > many good porting shops with expertise knowledge in this area either. The
> > final product would probably cost almost as much as a set of new high-flow
> > heads anyway - especially to get close to the flow numbers of Buick 300
> > heads. So how can you make these motors perform without taking out a second
> > mortgage on your house?.......
> >
> > Enter roller cams..... Roller cams allow a larger volume of intake charge to
> > enter the cylinders when utilising standard cylinder head ports, relying on
> > the faster opening ramps of the cam design (usually at a higher valve lift),
> > all this adding up to improved performance. The Australian Commodore V6
> > (Buick variant) is one such engine which benefits enormously from the
> > advantages of an OEM hydraulic roller camshaft - having an almost flat
> > torque curve throughout the entire rev range, resulting in a very tractable
> > engine. A high capacity Buick/Rover V8 however, has very good low end torque
> > but dissapointing top-end power due to standard heads inability to flow
> > sufficiently for the increased engine capacity. A hydraulic roller cam could
> > compensate for this by increasing the flow but not necessarily the cam
> > duration, resulting in a flexable engine throughout the operational rev
> > range with good idle characteristics. Sound too good to be true? Believe it!
> >
> > It appears that instead of relying on a possibly suspect porting job, or
> > purchasing a pair of expensive heads, there could be another more reliable
> > cost effective alternative. I'm certainly not saying that a hydraulic roller
> > cam alone will be sufficient to achieve all the breathing requirements of a
> > high capacity engine - but it would certainly come close. After all, nearly
> > all current performance OEM engines with pushrods use roller cams nowdays.
> > As there is also a need to develop larger capacity versions of the
> > Buick/Rover V8, there would also be a requirement to overcome the standard
> > engine's breathing limitations without resorting to high dollar techniques
> > like turbocharging and supercharging.
> >
> > ......and finally to my questions: Is there a hydraulic roller cam available
> > for the Buick/Rover V8? Who is the supplier and at what cost? Can one of
> > these cams be fitted to this motor or are the modifications required to the
> > block too extensive (i.e. lifter gallery oil passages)? Can the lifters,
> > retaining plates etc. from the Buick 3.8L V6 (late 80's) be adapted to fit?
> > Remember - the lifters from the old Buick V6 will fit the V8 (I heard that
> > somewhere!) and if that's the case, what mods were done to the Buick V6
> > block to fit the roller cam and lifters. Since the V6 block is (or was)
> > basically cast in the same mould as the V8 (minus 2 cylinders), can the same
> > mods be applied to the V8 to fit the roller cam and lifters?
> >
> > Mmmmmm - I wonder if the Shadow knows?
> >
> > Paul Rakich
> > Rover SD1 V8 SE2
--
Ted Schumacher
tedtsimx@q1.net
http://www.tsimportedautomotive.com
Fax: 419/ 384-3272 (24 hrs.)
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