Tappets

[Paul T.]

My winter project is to give the CYL HD a refresh including re-shimming the tappets, my question to the font of knowledge is can these be replaced with a heavy duty hydraulic type 🤔

 

I know of HPC engines that have been tuned to rev to 8.5K while still successfully using the standard tappets, I guess i'm a little tired of the noise

 

Is this becuase the cams have a less agressive profile on the HPC and the valve lift acceleration on the VHPD is too fast for the HYD's to keep up 🤔

 

Cheers Paul

[CageyH]

I think the cam profile is too aggressive for the Hyd tappets.

You could probably change to a Piper 285H cam without affecting the power output too greatly.

 

Only dead fish go with the flow....!

[SLR No.77]

As suggested the Piper 285 is available in a hydraulic profile, designated by the "H", and is still good for 200bhp. Therefore necessary to swap cams and followers.

 

If you do decide to change and sell your solid followers, I'd be very interested. I've been looking for a set for a while for a vhpd head I'm working on

 

Stu.

 

www.superse7ens.co.uk..........the rebuild 😬

 

 

[oilyhands]

Thr VHPD profile is actually very mild in terms of valve acceleration, unfortunately the ramp is cut for solid tappets so you cant use hydraulics. As suggested the BP285H is a good alternative profile and has much higher valve acceleration and greater overall lift.. however they are not straightforward to swap to because

 

i) the VHPD springs will not accomodate the lift without coil binding

ii) the VHPD caps are unsuitable for hydraulic followers

iii) the cylinder hyead may not have the feeds to the follower bores required to charge the followers with oil

 

Oily

[oilyhands]

Stu,

 

It is perfectly possible to run the VHPD cams on converted hydraulic followers, the profile is not too agressive for them when converted to solid using shims.

 

Oily

[SLR No.77]

Yes, Rob Walker's offered me a set that I think you converted a while back, but currently the valves are all assembled with vhpd caps and springs. I'm being patient and waiting for a set to wander by! If nothing turns up by the time the rest of the engine is ready, I think I'll need to swap the caps and go the converted route.

 

Stu.

 

www.superse7ens.co.uk..........the rebuild 😬