Installing thru hull tips
 

I just got a set of quicksilver 4" thru hull tips and before I drill massive holes in my transom I figured it would be in my best interest to ask a question lol the tips are 4" but there is lip for the exhaust house that's a little less than a 1/4" so when I drill the hole should I drill a 4 1/4" hole or should I keep it as small as possible and if I drill a 4" hole will I be able to squeeze it in? I'm guessing the best idea is to drill the 4 1/4 hole so I don't crack or break the fiberglass but I figured I would ask for some better advice :)

Go 4", then finish the hole (or any slight adjustments) with a simple sanding flapper wheel.

I'd drill a large enough hole.
Sounds like 4.25 is that size.

I'd drill the holes, then resin them after, so the transom doesn't have the option of water seepage and ultimately rot.

Also, make sure your holes are inline good with the risers, so that you dont have an angle on the rubber hose. The rubber can burn thru if theres a decent angle.

Everything he said, plus put a bead of marine silicone under the outer flange of the exhaust tips and coat your screws in LifeCaulk before you screw them in.

I would say NOT this. Go with the 4" for a several of reasons: Your flange bolt holes are already tight to your 4" hole, for this reason its always good to use at least a simple drill fixture for your main pilot hole and your mounting flange holes. Nothing wrong with having the tips snug in a 2-1/2" transom; the gel is not going to crack there...a simple chamfer to the gel with sand paper is adequate. The main thing here is carefully determining where your main pilot holes are placed. I used some simple white thin pvc drain pipe that fit perfectly on the riser. I then extended it to the transom and traced around it - determined the center of the traced circle and drilled the pilot hole using the fixture to keep things perpendicular. I drilled the pilot hole for the other tip from the outside the boat to ensure good cosmetic placement - you'll be very close on the inside as well.
Unless you can find a deep hole saw, you'll be cutting the hole in 2 steps; from inside and outside the boat, so again, the pilot holes are important. Here is a simple drill fixture that would be adequate for the job: http://www.acehardware.com/product/i...a=pla_18465513

If you are not in a hurry, a great way to make sure you never get rot from your screw holes is to drill them out oversize, say 1/4 inch, and then pack marine epoxy into the hole. After it has cured, drill your holes in those spots to the appropriate size for your screws. You will get excellent bite, and you will never need to worry about how well your caulk is sealing. This might be overkill for something like exhaust flanges, but it is a very good idea for something like trim tabs or K-planes.

Budman II I like the way you do things.

Why you would want to drill a hole that's not large enough for the pipe to pass through and then use an abrasive wheel to enlarge as opposed to just drilling to proper size hole escapes me. Having 1/8" of "play" around the tips is not detrimental.

To be clear Keith p........are you saying that the greatest outside diameter that needed to pass through the transom is 4.25"?
If so, you will never "squeeze" a stainless tip through a lesser opening than the tips largest outside diameter.

Ahhhh, but once you are married and with child(ren)...............
:eekdrop:

Keith, can you post a pic of these tips? i find it hard to believe they only gave you less then 1/4" of lip to mount the exhaust pipe onto...

There be confusion in this thread arrrggghhh.

I think this will help notice on the hose side the lip with the undercut.

http://www.ebay.com/itm/Quicksilver-...-/271885306151

And in case the link dies on ebay

[ATTACH=CONFIG]542009[/ATTACH]

Exactly! That shows why he needs a 4.25 hole. He can achieve that result by drilling a nice concentric hole with a hole saw or he could drill a hole that's too small and sand it out to 4.25". :whistle:

I agree with VC you have to read what the OP said carefully and look at the pic the long side being the hose side that lip is more than 4" by about 1/4" he says. You really don't have a choice in cutting a hole the size of that lip..... well you could go with a smaller hole and a larger hammer but I don't recommend that!

This is another case of pics are important!

Yes! Those are the exact tip I have! The part that goes through the transom is 4" but that little bump at the end where the hose goes on is a little less than 1/4" I ended up finding some directions that I didn't know were in the box lol and if I'm reading them correctly it says drill a 4 1/4 hole in the transom I will post pics of the directions when I get home.. But while I have everyone's attention lol I was wondering what the downward angle from the risers to the tips would have to be? I bought a set of corsa captains call diverters and it's going in an 86 formula 242 ls with a 5.7.. So I bought the tips expecting to just run rubber hose to them from the risers but then found a deal on the diverters I couldn't pass up and bought those.. While doing some measuring I realized my motor sits to low in the engine bay causing the risers not to be high enough.. Long story short lol I bought 6" riser extension blocks and want to put in the corsa diverters but I know that there has to be a downward angle just not sure on how much of a downward angle

Veneer calipers a corresponding hole saw and good to go. What am I missing?
FYI another poster here earlier this week had 6 used for sale in swap shop cheap.

But what should the downward angle be?

Also, run the hole saw in reverse as you start your cut. First 1/8" or so deep is good. Then, proceed in forward to just past 1/2 the thickness. (Roughly 1 3/8" deep)
Repeat from the bilge side out.

With those type of tips you have no control of the angle...the flanges are 90* to the pipe so they can only go on one way unless you make yourself some wedges to tilt them.
As far as the holes goes....get the closest hole saw you can get to clear that lip.....if it were me i would go slightly smaller and sand/file it open to size. I have cut holes that were larger then the pipe and the issue that pops up is that sometimes the mounting screws don't get enough material to grab into and start breaking out because the side wall is too thin....then you start shifting the tip to one side to get two good solid screws in and the 3 or 4th screws are barely holding onto anything....

Also, a good battery drill with a cutch is the tool you want.

If a pistol drill bites ( and it's going to) when you're cutting, bad stuff is going to happen!

Your existing exhaust riser has the angle built into it already (5 to 7 deg?) your just putting a straight 6" riser extension on correct if so the angle will not change. You want to fit the diverter in with a short hose close to the riser and hose connections down to the thru prop connections.

The above assumes you have a riser like this.

http://www.michiganmotorz.com/mercru...aTYhoCb0vw_wcB

Looks like this when done! Except you will have a riser extension in and more hose down to the thru prop connections

https://www.youtube.com/watch?v=eaDTAEdc8Kk

Mines a little different since it's an 86
http://i1102.photobucket.com/albums/...FC939EEA90.jpg

Sorry guys, I guess I need to sharpen my reading comprehension skills. Never meant to imply it needed to be sanded 1/4" ...but then again some one may have taken it that way. Great catch vc!
D

I had an older Mirage with twin 5.7 it was an 88 with thru hull already so I got nothing. I would think if your's is like Wally said 90deg then it has the the jacketed riser and it's not a wet exhaust but jacketed in which case you won't need to worry about the angle, BUT confirm that or maybe someone like BUP or one of the other guys that have worked on all versions of these will chime in.

Good luck with the mods and add some pics and let us know how it went.

Ok new question lol where should I put this hose? In the riser or the riser extension? Was hoping to get it all done tonight but the company I ordered the riser extensions advertised with the gaskets and hardware and they showed up with nothing :( I hope a local marina caries them I'll have to pick them up tomorrow

http://i1102.photobucket.com/albums/...44C3D2AC_3.jpg

Well here's the final result

http://i1102.photobucket.com/albums/...A04DE99086.jpg
http://i1102.photobucket.com/albums/...89E05D2B49.jpg
http://i1102.photobucket.com/albums/...53CC0BDC2D.jpg
http://i1102.photobucket.com/albums/...27B92AE584.jpg
http://i1102.photobucket.com/albums/...6B945E69C5.jpg