Vhpd

Technical Help for the A & K Series Metro. Please state what year and model you're referring to for better responses.
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Wibblyp
Posts: 87
Joined: Wed Mar 15, 2017 4:41 pm

Vhpd

Post by Wibblyp »

Should I buy a pair of Vhpd cams ? Currently running a 1.8 with possibly a vvc cam. If these cams were cheap would they provide any benefit ?

Ta
Paul
Dave VVC
Posts: 69
Joined: Thu Mar 16, 2017 7:40 pm
Location: West Mids

Re: Vhpd

Post by Dave VVC »

VHPD cams are a solid lifter profile, so no good with hydraulic cam followers,
so you would need to convert to solid lifters and double valve springs as the
powerband peaks at higher rpm.
Also you would need a mappable ecu as the std one wont cope.
Wibblyp
Posts: 87
Joined: Wed Mar 15, 2017 4:41 pm

Re: Vhpd

Post by Wibblyp »

So if I did as you suggest and went solid and emerald for example, would the Vhpd cams be a worthwhile investment ?
Dave VVC
Posts: 69
Joined: Thu Mar 16, 2017 7:40 pm
Location: West Mids

Re: Vhpd

Post by Dave VVC »

Hi, yes you would need to convert to solid lifters with the appropriate springs/caps etc and a mappable ecu, the std ecu wont cope.
The mgf supercup cams were Iirc285 - 290deg duration, and were good for 190bhp, with the springs
I had with my head, valve bounce was @ 8400 rpm, which is why I did my trackday VVC engine
keeping the VVC mechs (as I like them), I worked out that If I miss-shifted at 7000 rpm from
4th to 3rd. (it does happen), the rpm would only go to 8200prm, so not trashing the engine
as you would do with hydraulic lifters, obviously I had to use solid lifters on the inlet cams
as well, but seeing as the hydraulic profile does not have anywhere near as much of a valve
opening ramp as a solid lifter cam (thats what tappet clearances are for), I reduced the gap
to 4 thou on the inlet cams only, otherwise the lifters would just get hammered, engine sounded
sweet with no noises, I had the supercup ex cam reground by Piper to one of their profiles that
was closest to one I wanted, which gave me with a light ported head, @ 180bhp with a lovely
drivable engine that almost passed cat emissions with no cat fitted!, I still have the engine from
when I removed it to fit the 20VT engine.
Wibblyp
Posts: 87
Joined: Wed Mar 15, 2017 4:41 pm

Re: Vhpd

Post by Wibblyp »

Thanks Dave,
One further question, is it not advisable to shim the existing hydraulic followers ?

Ta

Paul
Dave VVC
Posts: 69
Joined: Thu Mar 16, 2017 7:40 pm
Location: West Mids

Re: Vhpd

Post by Dave VVC »

Hi, you cant shim hydraulic followers, as they run against the cam base circle,
You would shim the solid followers, as the clearances would change simply by
lapping the valves in, Its a bit time consuming on a 'K' head as the cam carrier needs to be fitted,
I had to make new shims for the vvc inlet cams when I did mine, as the cam base circle was larger
than the ex cam, plus I closed the gap on the inlet cams down to 4 thou, the ex cam was shimmed
as per Pipers settings Iirc, 10 thou. One thing you must check when fitting the solid lifter valve caps
is the part of the spring cap the shim sits in is not higher than the top of the valve stem, as the shim
must sit on top of the valve stem, 2 things cause the spring cap to sit higher is worn valve collets,
(quite common), and worn spring caps where the collets sit, also having worn spring caps, reduce
valve spring force when the valves are closed. Dont forget, solid lifter spring caps are not the same
as hydraulic caps, they are machined to accept the valve shims.
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