Rocker Arm Snapped After Rebuild

[Sean_Cassidy]

Hello all,

So, I bought an e30 that needed way too much work, wound up rebuilding the entire engine and have yet to get it started (I believe the injectors need replacing as the rest of the fuel system was severely gunked up). That’s beside the point. So I went to take off the fuel rail and in doing so removed the valve cover to gain extra clearance, and to my dismay I found cylinder 4’s intake rocker arm broken. I’ve done absolutely nothing aside from crank the engine over - it has never started, much less revved, and I’m absolutely certain that both the cam shaft and crank shaft were at TDC when installing the timing belt. It has a brand new timing belt, tensioner, etc.

My question(s): are there 2 TDC’s on the head? Like one for the intake and one for the exhaust? And, are there other reasons that a rocker arm could snap aside from contact? Such as poor valve clearances (which I’m quite certainI did correctly) or issues with structural integrity of the rocker arm?

Any thoughts are greatly appreciated!

Thanks in advance.

[digger]

What does rebuild mean? What rocker arms are being used and are they new or used?

When piston 1 is at TDC the valves are either:

• Both closed (end of compression stroke beginning of firing stroke); or
• Both open a during overlap (like 1mm off the seat with stock cam) which is end of exhaust stroke and beginning of induction stroke

The ”head” will be at TDC (cam gear mark aligning with mark on head) every second revolution of crank