#2 CHT Higher than the rest

McPilot · #1 08-16-2016, 07:05 PM

Hello...

my #2 CHT runs about 20-25 deg F higher than the other cylinders. I did a search and saw that a fellow VAF member did a baffling mod to correct this. It looks like his baffling may be a little different.

He drilled a hole in baffling to allow air flow to the lower fins on #2 cylinder. I am thinking that this is the reason for my issue. It is my thinking that even though the #2 cylinder is obviously in front that the lower fins get bypassed by the air flow.

It looks like his baffling does not cover the lower fins on #2 cylinder as mine does. Any suggestions?

flyingriki · #2 08-16-2016, 07:07 PM

Check your sensor first.

lr172 · #3 08-16-2016, 07:13 PM

My #2 is also 20+ degrees hotter than my others. I just did the mod that a few others here did, directing flow to the lower fins. I hope to test fly tomorrow and will let you know if it worked for me as well. My baffling looks the same as yours? I will try to remember to snap a pic or two to show you what it looks like.

McPilot · #4 08-16-2016, 07:51 PM

Quote:

Originally Posted by lr172

My #2 is also 20+ degrees hotter than my others. I just did the mod that a few others here did, directing flow to the lower fins. I hope to test fly tomorrow and will let you know if it worked for me as well. My baffling looks the same as yours? I will try to remember to snap a pic or two to show you what it looks like.

That would be great. Thanks!

jimgreen · #5 08-17-2016, 12:24 AM

Couldn't tell if yours is carb or FI. A dirty injector can make a difference.

McPilot · #6 08-17-2016, 02:10 AM

Quote:

Originally Posted by jimgreen

Couldn't tell if yours is carb or FI. A dirty injector can make a difference.

It's a carb.. The baffling seems to be the culprit,,,

RV Jerry · #7 08-17-2016, 08:56 AM

Other people such as Dan Horton have spaced baffle away from cyl. To allow more air flow around cyl. Notice how cooling fins are machined which leaves no fin area.

McPilot · #8 08-17-2016, 08:58 AM

Quote:

Originally Posted by RV Jerry

Other people such as Dan Horton have spaced baffle away from cyl. To allow more air flow around cyl. Notice how cooling fins are machined which leaves no fin area.

Any photos?

Mike S · #9 08-17-2016, 09:25 AM

Dan's thread on baffle mods for cooling the finless area is here http://www.vansairforce.com/communit...ad.php?t=37835

Another thing to check is the fin area between the valves. Look down from the top of the engine, between the top spark plug and the valve cover. The cooling fins in this area are often somewhat plugged up with casting flash, and need a bit of touching up to let the air flow through.

lr172 · #10 08-18-2016, 08:15 AM

Mike,

I did the mod to route more air directly to the lower fins on #2. That cylinder had been running about 20* or so hotter than the next two. I did a test flight yesterday and #2 was the same as #4, so the mod dropped the temps about 20*.

Here are two pictures of the install. You can't see it, but I cut out a rectangle in the baffle about 3/4" high and covered most of the horizontal area of the cover. I am not sure that I need to route air to the upper fins, but did anyways. the holes in the top were 1/4". I figured that I would keep these minimal and drill more or larger as necessary. Overall, it was a simple mod. I chose not to remove any baffling and used rivets on top and just RTV below.

Larry