Timing issue

[Tony Brooks]

Just to recap. The OP mentioned exhaust coming from the inlet. That sounds like a valve or valves stuck open. Apart from what I said about carbon, I wonder if the OP has maladjusted the valves when he refitted the head. I don't know what method he used and as he did not know about both rockers moving he may well have got it wrong.

[Tracy D'arth]

9 minutes ago, Tony Brooks said:

Just to recap. The OP mentioned exhaust coming from the inlet. That sounds like a valve or valves stuck open. Apart from what I said about carbon, I wonder if the OP has maladjusted the valves when he refitted the head. I don't know what method he used and as he did not know about both rockers moving he may well have got it wrong.

Good point Tony. Does the OP know how to set the tappets by rule of 9? Its the easy way. If he has set them wrong there will be poor compression hence no start.

[john.k]

These engines have very little space between piston and valve head..........IIRC ,one tooth out in timing and valve will hit piston.............however .one thing Ive seen is a pushrod not in its lifter socket ,again if this is missed at the hand rotation stage ,serious damage will be done . 

[Tracy D'arth]

7 hours ago, john.k said:

These engines have very little space between piston and valve head..........IIRC ,one tooth out in timing and valve will hit piston.............however .one thing Ive seen is a pushrod not in its lifter socket ,again if this is missed at the hand rotation stage ,serious damage will be done . 

I must disagree.

This engine is quite tolerant when it comes to valve to crown clearance.  The valves are perpendicular to the piston crown which is flat so any crash is less likely to bend valves than in an engine where the valves are inclined. The rockers usually bend first.

I have had BMC engines in the shop where the timing chain has jumped on the worn crank sprocket by several teeth and valve crash has not occurred.  Occasionally this has happened to such a degree that the combustion has billowed out of the induction inlet on every firing stroke.

If a pushrod is not located on the adjuster ball, the valve will not open hence no crash there either. But it will bend the pushrod.

Edited October 2, 2022 by Tracy D'arth