valve clearance question

[Robert J Hampton]

I have just replaced the head gasket on my AD3-152. While I had it down I readjusted the valves .012 cold but I think I may have got them a little snug. What would the symptoms be if the valve clearance was not enough? The engine starts great, my only concern is what sounds like a slight sucking sound coming from the exhaust. Would it be wise to readjust with a little more clearance?
 

[Jerry/MT]

Your intake valve lift would be a little bigger and your power would come up bit due to more airflow. Your exhaust valves have less seat contact time and run hotter.
 

[Mike in Mn.]

I'm not an expert on that engine but 12 seems a little tight to me. I would re-torque the head gasket and re-adjust the tappet clearance according to the book. Sometimes the exhausts require more clearance that the intakes. Get it hot, re-torque the head and re adjust the tappets while hot.
 

[Robert J Hampton]

readjusted valves and runs right now. thank for your replies.
 

[DavidP, South Wales]

Hi Robert, bit late coming in on this one but it is essential that the engine is at number 1 TDC for both phases of tappet adjustment. This is confirmed by the TDC line being visible in the engine backplate inspection hole.
DavidP, South Wales
 

[Phil Tibbetts]

I've always felt it was better to have them a little loose than too tight. Never seen a burnt valve from them being too loose. I'm not talking a lot but if your feeler gauge is slightly loose at .012 and tight at .014 I would feel good about that.