valve clearances

tim hill · rice boy Joined: 23 Oct 2001 Posts: 44

will my valves hit the top of my pistons? i have a g200 bottom end and im currently getting 1 1600 head done up out of three. the heads' casting number is 14 and it will be getting faced, not machined, alloy rockers off some other head, a big cam from another head and ported. this head has the bigger valves and i heard that they could hit the top of my pistons. the pistons in the g200 are standard flat tops.

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

To get a head faced, you use a machine, hence the term 'machined', so its the same thing.

The only way to tell with any accuracy is to dummy assemble the head, smear plasticine or bluetack onto the tops of pistons 1 and 4, bolt the head to the engine with a gasket, and then turn the engine over. The valves will imprint into the plasticine/bluetack and you can measure the clearance with a vernier calliper.

No one here is going to know if your cam and your head combo will make your valves hit your pistons. You should be telling us if they will hit.

Ben Wight