Upgrade Cam Cap Bolt kit

High tensile flange headed upgrade bolts for z20le* cylinder head cam caps

Most upgrade cam manufacturers recommend the use of upgraded bolts, not many actually know what to use – we use these every time we take the cams out of an engine , we have tested these bolts in the hundreds and we are finally happy to say they are fit for use.

We find that torquing these bolts into 10NM works well , always make sure the threads are clean, lightly lubricate the bolts with light oil before install.

These upgrade bolts require no modification to the cylinder head for install , they are a direct fit . They can be used if simply rebuilding the engine with standard cams or with our largest off the shelf performance cams.

RND Motorsport Z20let/r/l/h Single upgrade valve springs

Having pushed so far on the Z20 engine , we are using what we know to make the more normal power builds better. Learning more on the subject of how much valve spring you need for what you are doing lets you free up some HP in not driving an over sprung engine. Making the springs more accurately lets you drop the pressure back off a little bit because the real world average spring rate is much closer to what you want, on a less accurate spring you have to make them generally firmer to account for the soft ones still being OK to run. This potentially could mean you are over driving 15 valve springs just to make sure the one weaker spring is still doing its job well.

As with most of our high quality items that we sell, these are UK manufactured by a very reputable company, they are much more used to hitting a less than 1% deviation on spring to spring. This is key to being able to run a much closer to desired spring pressure without so much extra for the sake of it.

Wound from high quality steel , both ends ground flat , micro peened and coated , pretty much everything you can do to a spring to improve its performance and life.

These springs will give you in the region 20% more initial seat pressure than a stock spring , with 10mm of lift then they are about 13% stronger than the stock springs. In some cases the other springs we have measured are around 35% stronger with 10mm lift, fine in some applications but not needed in many others. These springs are set to be just right for most fast road cam applications. If you need a little more spring pressure then a 1mm shim will bump the pressure curve on by 10LBS , we have not required this option on anything we have tested so far.

Free length - 45mm

13.00mm lift before bind using stock valve spring retainer and stock seat.

Max lift recommended 11.5 mm

Installed seat pressure with 34mm install height – 79 LBS +/- 1%

pressure at 10mm lift with 34mm install height – 158 LBS +/-1%

Billet Steel Cylinder head hollow dowel pair - 

Replace the junky standard ones for some of these , proven to not crush down and allow the head to move so much