Replace bad GT40 heads with aluminum ones

I have a 1996 Ski Nautique with a 351w pcm motor. My stock gt40 heads are testing bad (leakdown test shows air leaking into intake. I want to replace the heads and came across Ford Racing ones on summits website http://www.summitracing.com/parts/fms-m-6049-x306
They look like they fit right in! Anyone use these or have any input before I pull the trigger?
Cheers
Tommy

I want to be able to run 87 Shell Marine gas with out any worries. Don't the p heads bump up the compression? The only 93 octane gas around here has ethanol in it. Is there a place that sells new p heads or do I have to gamble on a used set then take them to a machine shop and hope they do it right?

If it runs good I am happy, just don't want to use something that is going to make me lose that low end torque that the boat is designed for.


THX!
Tommy

I do not use ethanol gas in my boat. It draws water in from the atmosphere from what I have seen and goes bad quicker. It tears up plastic and hoses as well. 87 marine gas works great in cars as well. I have seen it make cars with failing catalytic converters run cleaner. I also get better fuel economy in my cars with as well.

Valid concerns Tommy however Pete and I live where it's easier to buy a hand gun on a corner than it is to buy gas with no ethanol We have to run it in everything we own. The only engine I have had trouble is in a Stihl weed whip and I'm not even sure that was the cause. Keep in mind Ford had to design their heads for where ever they were used so they had to be for all 50 states. I personally would be more worried about dissimilar metals using plain water than running alcohol in the fuel and really that's not a problem in fresh water.
The reason you get better mileage in a car with no ethanol is because ethanol has less btu's than gasoline. I have heard that is why you get better mileage with a top tier gasoline compared to a no name brand. A no name will sell for price and can use up to 10% ethanol where as a top tier might only have 5%.
As to compression you will have to check out what the aluminum heads have for chamber volume,they too might raise it,but aluminum does disapate that heat better. I believe my low end with the p's is better now than with the early 70's heads I had. You can buy remanufactured heads.

As Gary mentioned, I too would be concerned with dissimilar metals. Yes, it has been done but with the expansion rate being different there's always a chance it won't work out. Have the old ones worked on or as mentioned get a set of the GT40's

Yeah I hope they can fix the GT40 heads for me, but if they are cracked then they are boat anchors. The ford racing heads are almost the same specs as the stock heads. That is why I like them. Skidim has the gt40 heads but they are a little to proud of them for what they are asking.
Where do you guys pick up reman heads(gt40p)from?

Check with your local machine shops, they may have cores sitting on the shelf. Many people upgrade to Aluminum heads for car applications and the old heads are set aside. You may find a spare easy if needed.