just about to dive into some work on my 455. one of the things is replacing the valve cover gaskets. I'm a 2 stroke guy.... so I'm a complete newb when it comes to anything with valves. so I'm just wondering if anyone has any tips? while I'm in there should I check any parts for play? just want to make sure everything looks Ok while I'm in there. also should I even bother with new aftermarket covers? they're awfully cheap on ebay. so I was debating it. thanks guys.

 

Do a visual on the rocker bridges. If they are still factory they will be aluminum and on occasion they can break. If all looks good just replace the gaskets (NO RTV) and reinstall the covers.
Also it would be a good time to make sure that the bolt holes are all flat to the rail on the covers. If they are mushroomed at all they have been over tightened and need to be flattened out before installation or you will have a leak.

 

I use the rubber gaskets, RTV on the valve cover side and not on the head. If you ever need to remove the valve cover you don't need to replace the gasket.

 

You should not use RTV on the surface of a gasket. Either use a gasket or RTV, not both.
If you have two gaskets that come together, then a dab it required for a seal, but never on the face of the gasket.

 

And don't overtighten the bolts when you install the valve covers. The last time I did valve covers I had an inch-pound torque wrench (bought for differential gear setup) and I actually torqued the bolts to spec, and for the first time in 40 years the valve covers didn't leak!

 

Make sure your oil returns on both ends of the heads are clear. If you see a bunch of what looks like plastic chunks, you may need to do valve guide seals. Make sure bot the head and the valve cover surface are clean and dry. I glue the rubber gaskets to my valve with a thin coat of black weatherstrip cement.

While aftermarket valve covers are cool if they are not the same dimensions of the stock ones, they may interfere with your accy brackets. Then you'll have to mod the brackets to get them to work.

 

Awesome! thanks guys! this is exactly the kind of info I needed. Just want to make sure I check and service what I need to in there before I clean them up and bolt em back on.

 

I have a torque wrench. does anyone know what the spec is for tightening valves covers on a 455 ? ?

 

I'm guessing your torque wrench won't go low enough. The spec is 7 ft-lbs (84 in-lbs if you have an inch-pound torque wrench).

Be sure the flange on the valve cover is flat before reinstalling. More often than not, the flange will have been distorted by a previous overtightening. I hammer mine flat if necessary.

 

If you have problems with the gaskets and covers separating when trying to put them on the head, try this trick. Buy four or five (per side) 1/4-20 set screws that are at least 1 inch long. Screw one in the head at each corner. Place the gasket over the set screws and put the gasket on over the set screws. Use flange nuts on the set screws and regular valve cover bolts in the open holes. Torque accordingly.

 

believe it or not the best luck I've had is to just use a hand nut driver to just snug even pressure.. less chance of over tightening...