MTFCA Forum

Given a slow revving, low compression engine like a model T, what difference would an extra .005" in the ring gap make. What may be the manifestations of this? In the past I was concerned with too tight clearance but thought little of a bit wider ring gap.

Allan from down under.

If it performs well, I wouldn't worry about it. On a T, I'd be inclined to go toward the upper recommended limit for ring gap. T's with modern rings will have better oil control than the stock rings. Too much gap is too much, of course. Excess ring gap when new might lead to premature oil pumping or compression loss as rings seat and as they wear. Too much gap, whether from wear, tapered bore, or excess initial gap will promote blow by, which can interfere with lubrication and cause overheating of rings, especially at the gaps or anywhere a poor seal occurs. Too little gap can lead to serious issues right away. An engine that is expected to be run hard might benefit from a bit wider gaps and a careful, extended break in.

To tight is bad. Can cause extra cylinder wear & ring breakage. Remember a T has no water jacket around the cylinders. A little extra clearance over the tightest manufactures standard recommended clearance is in order, IMO.

A fellow motor builder described extra clearance as not so critical. Its like trying to throw a bucket full of water thru a key hole.
That being said, I set piston clearance @ .0045-.005. This makes for a wider ring gap with standard ring sets, so I fit .010 over bore rings to stay out of the excessive ring gap range. My memory says .016" - 018" which I dont rely on, so I check the recommended gaps according to a motors manual recommendation for 292 Y-blocks. Top ring should have the most clearance due to running hotter.