DRJ78

Appreciate everyones feedback. I contacted Lynn and will be having him complete an annual and seeing if he can determine the issue. I'll follow up and let everyone know what it turned out to be.

Yes it does only happen in the first 20 minutes or so of flight it seems. I have not noted which fuel tank. I will do that next. I use ROP settings at cruise. I tend to get around 10.5 GPH to the best of my calculations on fuel flow at those settings. I will not commit to that being 100 percent accurate.

I've put 350 hours on the plane. I normally climb at 100 MPH at 2500 RPM and Full throttle. At cruise I'll generally run 25 Squared. I lean slightly on the ground but possibly not aggressively enough. What is morning sickness...?

GRJ and GSXR thank you for recommendation.

It ran rough enough my first assumption was some sort of detonation and I wanted to end it as quickly as I could so I leveled off for air flow. I'll add some more context. The last time it did it was on takeoff from KMRH. Full rich mixture. Ran rough. Leveled off and reduced power. This was at 1200 feet. Smoothed out. I do not have a fuel flow gauge. I agree an engine monitor would be great and has been on the agenda for last year or so. $4,000 in re-doing the ignition system ate into that budget earlier in the year and now Further background. The first time it did it was I initiated a climb from about 2000 feet and forgot cowl flaps. Ran rough, leveled off, opened cowl flaps. Smoothed out. That was when I had him boroscope and do a compression check. Unfortunately I did not get a CHT that time. Since then when it has done it the CHT has been around 360.

Hey Guys. Got a 78 201J Model. Engine has about 400 hours on it. On climbs it will run rough from time to time. When it does if I level off and enrichen the mixture it will smooth out. I only have CHT on one cylinder. In climbs it will generally hover around 360. It did it once 10 hours ago then went away. Did it again just the other day. Had our A&P boroscope the cylinders and perform a compression check. All cylinders were over 75/80 and cylinder walls looked great. Airplane had brand new spark plugs, ignition harness, and magnetos put on it last annual. Any idea what this could be? I know it's rare to get detonation on a non turbo engine. Cowl flaps open and again CHT is around 360. I'm in North Carolina. Any recommended service centers within 300 miles or so that can solve this issue? My longtime A&P recently retired and I'd like to find someone to solve this issue as I don't feel comfortable flying it until it's fixed. Thanks.