Rover Big Valve heads

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peterc
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Rover Big Valve heads

Post by peterc » Mon Jan 13, 2020 4:50 pm

Hi Guys, does anyone have any experience of using big valve heads on Rover V8’s
I’m currently investigating options on enhancing my 4.6 and RPI are recommending their Merlin Heads. These are completely new having been redesigned to improve flow over a standard Rover head but also incorporating big valves. 43.9 inlet and 36.8 exhaust.
For reference a standard Rover head uses 40 inlet and 34 exhaust so that’s 20% bigger inlet area and 17% bigger exhaust over standard. Sizes are roughly the same as a TVR 5.0L big valve unit.

I’m concerned that having too bigger valves would affect the low down torque and smooth driving in traffic although I appreciate that the cam design will be the deciding factor.
Any comments.
Peter C

SiJackson
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Re: Rover Big Valve heads

Post by SiJackson » Wed Jan 15, 2020 9:36 am

I had a pair of ported group 4 spec big valve heads from John Eales on my injected 3.9lt Land Rover Series with a hi torque cam from Real Steel to give it back a bit of low end and it was superb. A real flat torque curve from 2000rpm up and plenty of top end when needed. Idle speed was 800 rpm and smooth as silk. The cam as you rightly suggest is key.

peterc
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Re: Rover Big Valve heads

Post by peterc » Tue Jan 21, 2020 5:21 pm

Just for info to anyone looking into using the RPI Merlin Heads. The shape of the rocker cover footprint is completely different to a Rover’s so you won’t be able to re use your Ford rocker covers as the adapter plates won’t fit. It’s possible to re design a new adapter plate but it might look a bit awkward on the corner profile.
So back to the drawing board. Might go for a cam change first to see what improvement I can get without upsetting the bottom end flexibility.
Si, can you remember which cam you purchased from Real Steel. I’m currently comparing the Kent 214.
Peter C

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