If you're running the HP500 Carb engine you really should change the valve springs if you haven't already. There were many problems with those springs which Mercury changed with the EFI. I understand they are still a little weak. You could do the gaskets at the same time.

HP350C

Do yourself a favor and replace the gskts now. I highly recommend Fel Pro marine gskts and while your there replace head bolts with ARP studs if you have the room, otherwise use ARP bolts. Detonation is brutal when it happens and the stock gskts are not up to the task if they have anything over 50 or so hours on them. I run a total of 30 degrees timing. I run 93 octane beacuse I fill up on the road to lake. I have found that 93 is sometimes hard to find on the water. It does make a difference in a pressurized application.

I'm sure there are many guys who are reading this that might be running boats without doing all this extra work, but I gotta tell Ya in the long run it is great insurance to know that you will be on the lake every weekend and not missing any time on the water. Where I live your days are numbered, so why not spend a little more time and bucks to gaurantee a trouble free summer??

Good luck guys,

Bigwavz

Whipples are the best, Best low end torque and mid range right where you need it. Dustin and there crew are top notch, Highly recommended!! They built me a custom manifold to use on Brodex pro 1 heads, fit like a glove.Had Pro chargers before and the boat always came out of the hole flat, with the Wipple it now jumps out like a rocket! and pulls like a jet plane.

Aero, thanks for the input. I have decided on the Whipple and looking forward to putting it in the water this spring/summer. I have corresponded with Dustin and you're right- alot of good advice and willingness to help. Thanks again

Tom

Cut NO corners!!
Do it right the first time and be happy. Make sure you have adequate water pressure and volume also. The stepped hulls will create grief; I know first hand. :(
I am going with the Cometic gaskets and have been told they are the toughest thing out there short of o-ringing your heads.
They look a little odd but have a great reputation.
Also, use studs and not head bolts.
Good luck with your project!
Dave

Thanks Dave, good luck to you too.

HP350SC. You are probably ok for this year. I have talked to Dustin many times and he has designed the kit for a stock system, so it doesn't need head gaskets. But the stock head gaskets will not last a long long time since they were not designed for this application. Detonation is brutal when it happens on any motor and I wouldn't expect to have any gasket hold up, but when you throw the air at it, we are not dealing with a stock setup. I am not an expert with this stuff, but when I pull a head off of a motor that has 250 hrs and the gaskets are deformed and falling apart, it's not hard to see why they don't last long after supercharging.
NordicHeat has a good point about the water pressure. Dustin told me that this is the most important thing, especially with stock heads to keep the hot air pockets from forming inside the heads. Hot spot in head = detonation = melted pistons.
hotlavey, add gauges to your list of $$$$$. I have a low water pickup on my imco lower unit and my water pressure is around 20psi, but when I had the stock bravo1 (5hours) I only had 5psi. You may have to install a offshore water pickup to get the water pressure you need. Your XZ might have a low water and side pickup, my friends does and his water pressure is just fine. I guess every setup is unique.

28 Eliminator,

You're correct. I do have both a low and a side water pick- up so I should be OK. I am getting guages as those are critical to this set-up.
By the by, I used to be an Eliminator owner a few years back when a 21' was considered a big boat. Man how times have changed. I have known Bob Leach from the get go when he was in Huntington Park working out of an old service station. A really nice person.
Thanks for the input, appreciate it.

Tom

hotlavey, it sounds like you have done your home work. I think you will have a kick a$$ boat when you get this thing done. Just take your time and do it right and you will never regret it.
If you have any questions in the process just post it here and we will be glad to help. I won't give advise unless I know the answer, and I know many here are the same way.

HotLavey,
talk to Dustin about the dual water pick-ups. Dual pick ups are not a good thing in all cases; so much so Merc has issued a dealer fix. If your X dimension is high at all this can cause major water issues. Dustin as well as Merc per bulletin 2001-01 both recommend the plugging of the upper holes in the drive. With higher X dimensions (which mine has) the water tends to pound into the nose and right out the side holes starving the motor. This obviuosly leads to disaster:(
I have plugged all my uppers and slightly opened the nose holes.
Hope this helps,
Dave
If your interested in the bulletin I could fax it to you. PM me...