Trim gasket for baffle fit?

Chicken or egg question...
Fitting baffles and on a few of the valve covers the orange gasket has a fair bit of overlap and keeps the baffle from fitting well. There is enough overlap that one could use an exacto knife and trim the gasket to fit better while still ensuring a good fit. OR...do you trim the metal of the baffle back to the oversize gasket? Hmmm..

On the gasket there isnt just the oversize all the way around, there is an extra tab on the top for fitting on diff size heads I guess. Can one just whack that off for a better fit? Looked over a bunch of build sites and cant see anyone mentioning this.

Thanks for any feedback.

You're talking about the gasket under the valve covers, not the gasket material used between baffle and cowl, right? If that's the case, I found that loosening the valve covers allowed the gasket to shift enough to fit the baffling (I only needed slight amounts of movement to get clearance). Once the baffles were on, I re-tightened the covers and there's been no problems since. Don't loosen the covers so much that the baffling gets between the gasket and head or cover; that would degrade the seal.

On re-reading your post, my gaskets didn't have the tab you are talking about. I can't see any harm in removing material that is not under the cover, myself. Use a steel rule to protect the gasket from accidental slips while you cut.

I hate those silicone rocker gaskets, and those are 2 of the reasons. Also, they have the ability to leak just as well as stock gaskets. You can trim them, but if you trim them too tight to the cover they may leak. I'd leave the baffle fit tight and trim the gaskets. If they leak, go stock. If you overtorque silicones they'll leak. If you undertorque silicones, you'll lose rocker screws (and they'll leak). There's really nothing wrong with a little proseal on a stubborn cover. Prying off the cover ten years after beats ten years of drips.

There are different gaskets.

"Real" Gaskets are too big. The correct PMA'd gaskets are considerably narrower as well as the non-PMA'd ones Van's sells. Buy the ones from Vans and they should fit with little or no trimming of the baffle.

Cork Gaskets need to be changed often if you want to prevent them from leaking. You can go much longer, but eventually they will leak and they cook onto the head and cover. The silicon holds up much better and if/when they do leak the job of cleaning them up and fixing the leak is very easy. They dont cook to the head and cover like cork.

Baffle / Rocker cover fit?

I've been working on my -6A baffles and in process on replacing all the seal material. A question in my mind has come up... There looks to be good potential of leakage outboard from the high pressure area around the rocker covers as the aluminum flexes in flight.

On my IO320 there are two fastening screws at a diagonal 10-4 o'clock on the cylinder. I do see some motors (angle valve?) that have 4 fastening screws at 10,2,4,and 8.

I'm wondering what kind of technique to use here or if it's an issue. Larger silicone gaskets might help "trap" the aluminum baffling?

JonJay said:

"Real" Gaskets are too big. The correct PMA'd gaskets are considerably narrower as well as the non-PMA'd ones Van's sells. Buy the ones from Vans and they should fit with little or no trimming of the baffle.

Cork Gaskets need to be changed often if you want to prevent them from leaking. You can go much longer, but eventually they will leak and they cook onto the head and cover. The silicon holds up much better and if/when they do leak the job of cleaning them up and fixing the leak is very easy. They dont cook to the head and cover like cork.

Click to expand...

I have always trimmed the aluminum baffles to leave space around the rocker covers. It makes future maintenance easier.
On a side note, I have found that many people over tighten the rocker covers when using the silicone gaskets which can cause them to leak.

over tighten the rocker covers

Steve, noted. 25 in-lb. Having this forum to crosscheck with my A&P hangar mate on good practice (along with docs) has been a huge help.

SDS Billet Covers with o-rings

Another great option are the billet covers offered by SDS. these have a machined o-ring groove in them. No more gasket...use the provided o-ring. Keeps everything captured and in place. Way less potential for a leak.. Plus...Ross will customize them!

http://www.sdsefi.com/sdsaero.htm

Not sure anyone's answered Bob's question yet, specifically regarding the gap between the baffle aluminum and the cylinder head adjacent to the rocker cover gasket, where plenum air can escape and reduce cooling effectiveness.

I haven't sealed that area but I noticed the same thing. Now I'm wondering if I should.

Baffles

Pretty easy to put a doubler all around the cutout for the rocker covers instead of just at the fasteners. I wonder how many people who don't like the silicone gaskets own or have use of a torque screwdriver that will give you the specified torque?? No leaks form my silicone gasket. I have a Snap On torque screwdriver and don't overtorque.