Operation of Type 4 cam?

Alpine · Post by **Alpine** » Fri Jan 23, 2004 10:01 pm

I haven't split my case yet so I haven't actually held one in my hand ... can someone describe how it functions? It only has four lobes, right? Working from the front of the engine (impeller end) what valves do the lobes open as you move to the back of the engine? For example, does the first lobe (nearest the front of the engine) operate the intake valves of the numbers two and four cylinders and then the second lobe operates the exhaust valves of the same cylinders? Thanks.

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Fri Jan 23, 2004 10:10 pm

Both inboard lobes operate the intake valves on all cylinders by sharing lobes...

Both outboards operate all exhaust valves...

This is how we can make split duration cams..

Guest · Post by **Guest** » Fri Jan 23, 2004 11:59 pm

So, if I understand it right, the lobe closest to the fan (on a 914 engine) operates the exhaust valves of the number 2 and 4 cylinders, the next lobe (moving towards the back of the engine) operates the intake valves of the number 2 and 4 cylinders, the next lobe operates the intake valves of the number 1 and 3 cylinders and the last lobe operates the exhaust valves of the number 1 and 3 cylinders?

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Sat Jan 24, 2004 12:35 am

Thats correct.

Alpine · Post by **Alpine** » Sat Jan 24, 2004 11:30 am

Ok, thanks. I'll be able to visualize it better when I disassemble the bottom end. Here's a picture from my Haynes 914 manual - the offset of the cylinders from one side to the other is obviously exaggerated but you would think that there could be no offset for the valves to be operated the way they are.

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Sat Jan 24, 2004 11:51 am

Forget all those books, and just tear it apart!

Books don't teach you much, dirty hands do!

I can appreciate your desire to do it right, but let the engine teach you. Make it run, thats what I did.