High CHT problem SOLVED

svanarts · Post by **svanarts** » Thu May 10, 2007 8:06 pm

At least I *THINK* so.

My CHT (I only measure #4) has been steadily creeping up. I've asked for suggestions via email and various forums and a combination of suggestions seemed to have helped.

Background:
During climbout in the summer months my CHT has been reaching as much as 425 degrees F. At this point I'd level off and throttle back until it came down to about 390 and then continue on climbing if I needed. Level flight saw CHT averaging about 395. Just a little too high for my comfort.

What's been done:
What I've done is to implement a suggestion by another builder that suggested I glass in the sides of my cooling ramps on the upper cowl. They were open and allowing high pressure air from above the cylinders to flow through the sides of the cooling ramps and into the low pressure portion of the lower cowling. I've also blocked off a portion of the (rather large) hole I had cut for my oil filter which is mounted behind #4 on the baffle.

I also did a very careful timing of my magnetos. They were only a little off but it was just enough to raise the CHT. That suggestion came from Bart LaLonde. The combination of changes have lowered my CHT by slightly more than 20 deg. I would normally see mid 380's on a day like today (70 deg) but this morning I saw mid 360's. I'll report back after doing some hot weather flying.

I may have to adjust my gerry-rigged oil cooling door to get the oil temp down as the weather gets hotter.

Over all I'm pretty please and much relieved.

Post by **Spike** » Fri May 11, 2007 9:49 am

Pictures needed.

aerial · Post by **aerial** » Fri May 11, 2007 12:04 pm

What kind of CHT guage and sensor are you using? I would like to install some kind of cheapo on one cylinder to see what's going on with the Mustang. I have noticed that on my Mag check the R is running a little rough. Now that you are the consummate timming expert I may have to make a trip to Oakdale for documentation.

Scott, do you run Marvel in your gas? How much and how often. TCP? Are you burning 100LL or MoGas?

svanarts · Post by **svanarts** » Sat May 12, 2007 3:52 am

No I don't run Marvel though I promised myself I would. I'm using the bayonet type CHT sensor and it's hooked to a Rocky Mountain MicroMonitor (state of the art back in the day). I run regular 100LL without TCP. I do get lead accumulation in my plugs though. I have to clean them every annual. You might just try to give your plugs a good cleaning and see if the engine runs any better. But come on down to Oakdale anyway just to be sure.

My RV buddies and I are planning another trip up to Shelter Cove soon too.