St170 valve springs are two different lengths. This is a problem on my new crate head as the cams are not the same as my older black top.

Standard Bt Zetec springs are all 44.5mm long.

The st170 Has two spring lengths.

Inlet 45mm

Exhaust 47mm

The 47mm are coil binding at just before full lift on both inlet and exhaust.

All lengths approximate

The cams are stamped as sports cams and are a blank that are sold to people like kent cams and ford. They have a model number that is similar to that used in a homelegated race series. But not marked up as kent. May be ford saved them for something special ?








Either way, one cam has more lift. I have two sets of springs so its not a problem.

New Rs pistons are no longer available. I should have had a set when they where. Oem rods havnt been available for a long time.

In my opinion the oem zetec rods are the weaker link than the pistons so making them weaker by reaming them to take used Gm pistons is more of a bodge than the st bottom end.

An Rs engine can be had for around a grand but a refresh with a new water pump won't be cheap. Fully forging a zetec is going to cost simlar money with machine work unless you can do this your self.

The deal with the Rs ecu is, you spec the engine to something like the rs and you plug and play. This will make it through an mot and will run like oem. It's a budget way of doing it.

Even with Ms or any after market engine management unless you're building and mapping the ecu as intended with megasquirt then you will soon be spending £500+ on the ecu same again mapping it. A little more for taking it back for tweeks then there are a couple of days of work and the transport to and from you mapper.

Any one can have 500hp if you check book will open that far. My 260 target is beer money and gets me away from the shit tv the wife watches.