Intake valve size gen 5 heads
 

Anyone know the correct intake valve size on a set of stock gen 5 heads?? 2.25?

Re: Intake valve size gen 5 heads
 

Black or blue motors ? Rectangular or oval ports ?

Black rectangular ports come with 2.19 intake valves.

Re: Intake valve size gen 5 heads
 

Rect. ports I am told the blocks are 94's and the heads are gen 5. Seems like my mech. may have put in wrong intake valves. They are 2.19 in them and mach shop says they should be 2.5 or 2.25? Don't remember exact. what size he said,regardless they are wrong. Ran ok for 60 or so hours. Did a leak down test and needless to say I am tearing down the second motor. :mad: Heads were supposebly brand new and he put together.Trying to figure out why valve size is wrong.
Jamie

Re: Intake valve size gen 5 heads
 

Sounds to me like you are working with the wrong machine shop unless its a custom or actual HP engine. A 94 is a Gen V. All mag engines both carb and efi/mpi had 2.19 and ALL HP versions had 2.25 intake valves.

You may want to reconsider your direction and find out whats really wrong. If someone put 2.19 valves in a 2.25 seat, you wouldn't have made it 60 hours.

Re: Intake valve size gen 5 heads
 

You are correct. The valves were 2.190 in the heads. Apparently there is not enough metal under the valve to properly seat,so 2.25 are going in. Bad design to me...

Re: Intake valve size gen 5 heads
 

I can't see your pics, I'm not a paying member. However, 2.19 valves in a 2.19 seat with a proper valve job are just fine and have been produced by the thousands. Anyone telling you different is misleading you.

Hopefully someone that can see the pics will respond for you. Please find out what the REAL problem is before you are back here asking again, not to mention quite a bit lighter in the pocket.

Tell us a little more about what your engine is and what caused you to tear it down.

Re: Intake valve size gen 5 heads
 

Engines are merc 525sc's,completly re-built with new parts,including heads. Starboard motor has not wanted to idle for some time. It would always stall around the docks. Seemed to be missing on 1 cylinder,but ran good WOT. Thought it may have been the carb and had that checked out...not the case. So we did a leak down test and found 3 cylinders above 70% leakage. Thus ending up tearing down. Not really a good reason for the intake valves to be on the edge of the seats in a new head with 70hrs.

Re: Intake valve size gen 5 heads
 

Port motor seems to run fine,but checked #8 cylinder last night and same thing. 80% leakage... Did not go any farther with the test on that one. Know it needs to be tore down too.

Re: Intake valve size gen 5 heads
 

I'm pretty sure that the 525 SC came with 2.19 intake valves. Do you know where the leakdown was escaping to? By your description it almost sounds as though you may have tuliped valves.....sucked up into the head just before it breaks off.

Are you sure your base timing was correct? Retarded will do significant damage as well. Does the engine show any signs of detonation?

Keep asking and digging, I don't think you found your issue yet.