Putting together a 440 for the family river cruiser (21ft. Jet boat) out of some old 440 engines I have around the shop. So far the plan is looking like I'm going to use the 68 block bored .030 over with a set of KB cast flat tops, part number 1263, on factory rods and crank. I'm going to throw a Mopar Purple Solid Lifter cam with .557 lift on 296 duration and advance it to about 108 degrees. Unless I hit 700 HP I'll never be able to spin it fast enough to reach peak RPM for the cam, so I'll shoot for the lower power band and more TQ.

Heads are the the big question mark in the build. I have a set of 346 heads I can have cleaned up and use, or should I go aftermarket? There really isn't an advantage other than flow from going Aluminum Heads because in the boat, temp is never an issue (other than lack of it).

From my calculations the KB flat tops will be about .11 in the hole without having the block decked. With the 88 cc chambers that will yield about 8.30 compression ratio. If I go with a set of 80 CC 440 source heads I will be up to the 9.0 compression range. Which is the most cost effective way to get my compression up to a usable number while maximizing the HP output?

I have either a factory 4bbl manifold or a Wieand tunnel ram to put on the boat depending on what performance the engine will deliver.

I also have a 72 .030 over block that I can use if I have them deck the block for compression. I know the machinist won't want to cut that much off the 68 block as he complained it was super hard and ate up his bits while he was boring it. Any thoughts on which block I should save for a blown 512 project?

Thanks for your opinions.

 

If your concerned with money I'd go with a set of 915 or 906 heads. Can probably pick either set up for $100 that need rebuilt. The 915 are closed chamber and will give you more compression. The 906 will flow better but will grant a little less compression than the 915. Of course you can take either set to the machine shop and pick up what the other is lacking if you don't mind spending the extra money. But be careful, you may be better off just buying new set of aluminum heads before you get done at the machine shop. Also aluminum heads are gonna be lighter than the old cast iron heads by about 40 pounds.

 

If you are boring the motor ? GET the correct pistons to raise the compression up to a 10 to 1 or spend 7-800 for a set of reworked 915's

 

I agree 10 to 1 is where I'd like to be, if not a touch higher. I just downloaded a compression calculator and it says I should be at 11.14 to 1 with what I have.

Does this sound right? Stock Block Height: 10.725, Stock Rod: 6.768, 1/2 of stock crank throw 1.875, Piston CH: 1.969. Leaves the piston .113 in the hole and says the compression would be 11.14 with 90 CC heads. I used a .040 head gasket thickness. Edit: disregard, apparently you get what you pay for and this app was free. Summit's calculator app confirms 8.21 to 1. The pistons were never fired which is why I wanted to reuse them.

Now I know why on the go fast boats I just do what the machinist say.

The go fast boat behind my daily driver. This boat runs a blown injected 468 BBC on alcohol. 12.5:1, 871 with a bird catcher. Motor is out, making sure the Challenger can tow it safely. I won't tow it far with the Challenger.