Intercylinder baffle question

[mr_matt]

Hello again,

What do you guys do or think about with the intercylinder gap on a Lycoming?

This is the gap between cyl. 2 and 4, it's .2" wide. The stock intercylinder baffle extends out to about the spark plug hole but outboard of that it's clear sailing, about 3 3/8" x .2"

Thanks in advance,

 

[rvbuilder2002]

At first, it looks like a large unnecessary leak. But if it were to be blocked off, you would be inducing the same cooling issue on the front side of cylinder number four, that exists on the backside of cylinder number three that people install the spacer washer or bypass channel in the baffling for.

 

[D-Dubya]

However, you can close off the gap nearest to the fuel injection port with some RTV. In your photo, the left fins will still get air while the gap closest to the injector port gets closed off. Just be careful not to go any further inboard (only about an inch) with the RTV or you'll risk causing the problem Scott references above. Nor do you want RTV to go any deeper than the tips of the fins, or you'll reduce air flow in the area on the left (as referenced in your photo).

While it's all clean and unencumbered, you get the biggest bang for the buck sealing off the gaps with RTV at the inter-cylinder baffles where they meet the cylinder barrel and the engine casing. You may have to bend some of the small tabs around on those baffles for a better fit as well.