Valve Cover to Cowl Interference

[rperry]

I recently acquired a 1953 C-170B with C-145 to which Superior Millenium cylinders were mounted (80 hours ago). Within the last 30 hours I now have a hole in the nose bowl from interior wear at the #5 (rt fwd) cylinder location and a hole in the #6 valve cover from wear against part of the cowl. Does anyone have experience with Superior cylinders (SA10200-A20P) or any other forward cowl interference problems who might advise me on these issues. My thoughts run along the lines of the Supeior valve covers or the whole cylinder assembly being "taller" than the originals. I'm looking for advice before embarking on my own solutions or parts swaps to alleviate the problems.

Dick Perry
(505) 856-7008

[blueldr]

I ran a set of Superior cylinders in my '52 C-170B and never found any difference from factory cylinders. There is, of course, a difference in the cowlings.

[marathonrunner]

I know someone at Superior I can contact to see about height, I will do that. I do not think they added height though. I would use a caliper and measure the height of the valve covers. That may be something that could cause it. Do you have anything on the mount that is different? Just thinking outside the box. I mean is it sagging or washers added or maybe some damage to firewall that may have affected this? As always it could be a lot of things besides what appears to be the problem. I will check though on the cylinders and post a reply

[marathonrunner]

Ok the cylinders are dimensionally the same as TCM's. I would think cowling issues of some sort. Good luck

[jlwild]

It sounds to me like your baffling is worn out between front cylinders and nose bowl. Repair it quick as cowling parts are very difficult to find .

[hilltop170]

Post some pictures of the worn areas and it might be evident to one of the members as to what is going on.

[c170b53]

A good suggestion just mentioned; check that the engine mount rubbers at the firewall are not worn.

[minton]

Another shot in the dark:

Anyone thought of checking the overall cowl (reinstall) after the top? Sometimes there is oblong wear in the mounting holes on the cowling @ the firewall end. Loosening the screws on the lower cowl section slightly and lifting the front of the cowl/ retighten the screws while holding upward pressure / check clearance from cylinder. If that helps and you need a little more now loosten the upper and lift again/then tighten while holding the upward pressure. It has worked for me in the past.

Just a thought.

[rperry]

Thanks for all the input. I identified the culprit as the short angle bracket at the front of the lower cowl where the nose bowl attaches. Apparently at one time the cowl was installed canted to the right enough for that angle to contact the valve cover, causing the initial valve cover damage (repaired). At last annual, before I purchased the aircraft, it looks like it happened again, causing the latest damage and reaulting oil leak. Even with the cowl screws loosened and and the cowl pushed to the left, there was very little clearance. I have a new valve cover installed. The angle is now ground down and a piece of 1/4" ID fuel hose installed over the exposed edge to act as a buffer in case of future misalignment.

Dick
C-170B, N3016A

[blueldr]

Are you sure that your engine mounts are not sagged to point that the engine allignment is deteriorated? This would also include the rubber at the firewall mounting points.