I am not sure if I am in the correct category. When installing the roof rail weatherstrip on a 1970 Cutlass Supreme do you notch it to fit around the blow out clips?

 

Mine is just tucked in, but someone else installed it and I couldn't tell you if it's correct. Doesn't seem to cause any issues, and no breaks in the strip.

 

Sounds like hardtop. I'm a big car guy, just to put it out there up front. And from earlier year - 1966...

I've had a particular focus on roof rail rubber / wind noise / water intrusion for years. Dig around under my user name for roof rail rubber & noise related posts in case they help.

Reproduction manufacturers make the foam roof rail rubber strips a little long on purpose. Not only can they sell for multiple models with one extrusion, the extra length allows the end user to adjust the start/end (front/rear) back & forth to get the best seal possible.

My first piece of advice is remove & clean your roofrail channels & get the old goop/glue/etc out of 'em. Consider polishing the visible edges to make 'em shiny for show. Use 3M dum-dum to seal the channels to the body on the upper side. A heat gun & solvent helps here in removing the old body seal goo. Assuming the lower (rubber retention side) is clean - test fit the rubber and run it for a few days/week before gluing it in. That allows you to listen for window whistles, noises, gaps, and to see if there are any physical inconsistencies you'd like to correct. More or less, take a few days to slip the gasket back & forth to get minimum noise/wind and hopefully water intrusion. Consider testing water fitness by blasting water hose at the window tops just to see if the squish you've set keeps water out.

Once you're satisfied with your idea of best fit _only_then_ glue it in with 3M black weatherstrip adhesive. I recommend this stuff since 3M sells a solvent for it. Much easier to use than silicone sealant you'll have to grind off....

Theory
I believe the top edge of the window-to-rubber seal matters a lot less than the inside-of-the-window-to-vertical seal for preventing water, wind & noise intrusion. The window top edges were not square in my cars, plus the windows are curved. After years of fooling with this stuff, I concluded the rubber edge that hangs downward like a tooth is what really seals the windows. I try hard to keep that vertical sealing surface as consistent and tight as I can. To be clear, I mean the outer vertical edge of the rubber seal against the inner vertical edge of the top of the window. Usually the interface about about 1/4" before gasket "squish".

Practically
Long ago my first instinct was to pull the roofrail foam rubber extrusion tight front to rear for a consistent seal. I learned that if you pull the rubber seal tight front to rear, it stretches the foam rubber so thin that it seals less well against both front & rear windows because it's stretched. What's better is to keep the most all of the length of the foam rubber seal and let it "bunch" just a little where you have inconsistent "squish" of window to foam rubber. I avoid variances more than 1/16"-1/8", and if you can, let the seal bunch at the front window corner, and maybe the front/quarter window seal. The idea there is to leave some extra foam where you can expect a bigger window-to-seal void.

Shim for tightness
O.k.,onto cheating. Haven driven "modern" cars for about 40 years, I'm impressed with how much quieter they are. And the older I get the more I appreciate quietness. For purposes of this post, be aware that you can get closed cell foam rubber in 1-1.25" widths which can be placed _above_ the roof rail channel between it & the body. This non-factory part shims the roof rail channel tighter to the window by reducing the window void by just a bit. As window rollers & regulator channels wear, windows just aren't as tight as they were 50 years ago. So shimming the sealing surfaces down is one solution to the tightness (aka quietness/water intrusion problem.

I've used this both on my 98 convertible & my '66 Starfire to good effect. This is not a recommendation, just an experiment you might want to try if you're dissatisfied with aging factory parts. If you got this route, you will likely need longer screws to secure the roofrail channels to the body through the closed cell foam shim.

Try it if you're into the experiment, have the time and patience. And don't compare old cars to modern ones. You'll never get a 60's - 70's car as quiet as a modern one. Later cars all have windows that wind up into door frames. Later cars don't have ventipanes (wing windows). Later cars have styrofoam in the doors. And multiple sets of seals to make them quiet. All those factors make the old stuff kind of quaint. Like an oil lamp vs. halogen light.

Anyway just a few ideas in case you'd like to dig in. Hope I didn't go on too long.

Cheers
Chris

 

Never cut into the skin of a window seal. It slips behind with ease. I used plasti-dip to restore the rubber coating.
I didnt glue my rail rubber into the chrome U channel. Been that way since 1990.

 

ok Thanks all good info. The channels were removed, cleaned and polished. New blow out clips installed. Rails reinstalled using 3m caulking strips. There is no glass in it right now but I am installing all new glass so I am going to wait until the new glass is in before i install seals. Thanks again for all of the tips and info.