89Mach1

I have Imco Powerflow short risers and silent choice on my carbed hp500s. I picked up a set of long risers dry to the tip for a steal and had a chance to see how they would fit today. Long story short, to make them work I'll need to make a wedge. These are a wet joint unlike Gil that has a dry joint and wedges readily available. Has anyone had to do this before or does anyone see a problem with wedges on a wet joint? Making them shouldn't be an issue as I have a mill to make them on. I'm assuming aluminum would be the best choice to go with? Thanks

Ballistic Beak

iTrader: (2)

89MACH1

Aluminum should be no problem, that's what the wedges for the gil style are made from and they don't have water running through them.

You'll have an extra gasket per side, which is extra potential for leaks. Make sure to machine the gasket surfaces with the appropriate surface finish for the type of gasket you're using.

Ryan

89Mach1

Thanks Ryan. Question though, what do you mean by machine gasket surface with appropriate surface finish? I plan on using the stock replacement gaskets. Is there something special I should be doing with the surface finish for these?

Jay

Ballistic Beak

iTrader: (2)

You mentioned access to a mill - depending on the how well the head is trammed to the table, what type cutter you use etc, you can make a surface that looks like someone cut it with a sawzall.
If you fly cut with too low spindle RPM and too fast a feed the finish will be rough and the leak path will be relatively straight lines from the water to the exhaust.
Not my photo:



Look at the top, that's not good. Imagine if there was a hole in that section, the leak path from the hole (your water jacket) to either the bilge of the exhaust - its a straight line. If the finish is bad enough, the gasket won't seal all the small valleys and you wind up with a problem.

Ryan

89Mach1

Gotcha. The mill is in my garage. Im not a machinist by trade, just as a hobby. My mill is trammed within .0005 and seems to produce a very nice finish. I understand what you mean now, smooth and flat, shouldn't be an issue.

On another note, would you worry about the bolts not sitting flat on the wedge or would you machine a tapered to flat bushing for the bolt?

phragle

iTrader: (3)

It liable to get expensive if it leaks..So I would do everything I could to make sure it didnt..

Griff

How much are they off????? I assume they are too high where they meet the tip.
I would consider having the tails modified instead of going with wedges.

89Mach1

Roughly they will need about a 1/2-3/4" wedge. I was only able to hold it next to the existing one on the motor today, so until I take one off and take measurements I can only guesstimate it by eye.

BUP

iTrader: (9)

Wedge kits really are not that much of a problem unless you can not obtain good gasket seal. Alot of Mercruiser Non Dry joint exhaust OEM stock apps comes with riser extension blocks as those require 2 riser gaskets with the riser extension block installed in between that are wet jacketed.

I would make sure all sealing surfaces are not warped - use a straight edge to check all of that out including the wedge kits.

CP / Hardin sell wedge kits as well but have no idea if they are exactly what you are looking for. They might be for Gil only. Can not remember 4 sure about it.

Ballistic Beak

iTrader: (2)

I have a 1/2 or 3/4 on mine, but gil style. I'm pretty sure I didn't use a tapered washer. I did have to open the holes on the riser flange to compensate for tipping them with the wedges.

Ryan