What pin height and rod length do you use? The few I have seen torn down the bores seemed to wear prematurely. Not saying it can't be done, but the few engine builders I have talked with frowned on it in a marine engine. This was years ago and technology is much better now.

When you want a big cubic inch motor it best to go to someone that is known for building that kind of motor they know what it takes to make them work. This kind of builder would be very familiar with the effect an oil ring coming out the bottom of a bore would have because the crank has so much stroke. Alot of guys build maybe 1 or 2 of a certain cubic inch motor who think they know what they are doing and says its a bad combination because things wear out prematurely... Not the case. There are guys that build motors and there are guys that build big motors.

i dont care who is doing the build,when you stick a crank with a stroke longer than 4.250 in a 9.8 deck block it will not be a long lasting engine.yes it can be done but in a marine application it is not recomended.a good builder will not do it because he knows it is not a good idea and can come back to haunt him.the guys as you put it that build big motors know better than to build incorrectly.

I jus had this conversation this weekend at a pokerrun with a engine builder.it can be done.but is not a good idea.

Corrected it for you.

4.250" is common in a short deck.

I was not saying it was good nor bad to build a 4.375" stroker 9.8" deck engine. I threw out the idea a few years ago to a few respected marine engine builders and they all said it was not worth the hassle. I have read on drag racing forums about how they like them is why proposed the question. I was only looking for information on rods and pin height to educate myself. This forum is for sharing knowledge and educating others.
Thanks

Through talking with some engine builders who are familiar with marine engines I have found a 555 is about the same price as a 540.

I understand what you are saying and agree to a point is a 4.375 crank in a short deck the best fit for longevity? No, it's not but neither is a 4.25. There is always compromises when building motors. Alot of guys would rather build a 4.25 motor because most of the time the is no extra work that needs to be done to the block. Someone who has built 40-50 of these motors is gonna have an advantage over someone who has only built 1 or 2. With experience comes knowledge and know what the proper rod length ring stack and piston skirt design will make a big difference in how long the motor will live. Does it mean its going to last forever? No, a marine engine will bring out any little flaw a motor has rather quickly put a blower on top or side of it and its going to bring it out that much faster... It all boils down to what your trying to do and how much you can afford.

thanks but my statement did not need correcting,there is a reason 4.250 is common and 4.375 is not but if someone wants to build a 4.375 stroke engine in a short deck more power to him,i wont do it but what do i know!

I want a tall deck 396 with a 3.76 stroke and some peanut port heads. My max RPM I would like to spin is 4000. I have a 2 barrel rochester carb for it. Its gonna be 11.5:1 compression with an RV cam. I plan to run it on 87 octane with projected tip plugs, cast pistons, 210* water stat, and 39* of locked timing. Shooting for an air fuel ratio around 15:1, for good MPG. I am hoping for 650hp at 4000rpm. I really need the midrange cruise