Piston Ring gap question

[Pugnowski]

Hello all,

question for any engine builders out there. I am in the middle of a rebuild of 99 Ford Expedition and am measuring the rings. My machinist bored the block .020 over and I have the correct rings. However, when I am measuring the gap of the top and second rings..I am already at the maximum gap by Ford which says .011 for the top ring. I can easily pass a measure through that, and even a .012.
Should I just by the next size rings up and grind down to size? Don't really want to just half ass it.....


Thanks in advance...

 

[stamp11127]

Measure the bore of each cylinder at 3 depths to make sure they are .020 oversize and not an issue with the bore diameter.

If those are correct then get with the manufacturer for the correct replacement rings. The set you have may be mislabeled.

If you have an old set from the standard size piston, measure those in the bore also for comparison.

 

[Pugnowski]

Ok..thanks..will do..I have seen recommendations from .0045 to .004 times bore diameter for 1st ring, .0035 for second, ..this is a NA motor, mostly stock...is that what you would recommend?
It just seems that Ford recommends a much tighter gap,..that is all...

 

[stamp11127]

The ring gap will depend on the type of piston and ring used. In the old days a top ring gap of .014-.016 on the chevy 327 was common. But with the epa requirements the engines are built tighter in today's world.

Personally I would go with the recommended specs.

 

[Pugnowski]

Thanks Stamp!..will do...

 

[stamp11127]

Something to be aware of is oil viscosity. As the clearances are tightened up the oils are thinner to fit in the tighter spaces. I still shake my head a 0w oil. Man that is thin....