Question for the JetHeads

[red_n_vegas]

I am thinking of taking my 454 BBC out (which has problems) and putting in a SBC 350. My questions are.
1.On my 21ft boat will I see a huge different in the speed?
2 Can the 350 be played with to hit 60mph?
3.Can the BBC motor mounts still be used?
4.Can the 454’s exhaust manifolds still be used?

[Essex502]

Not a "jethead" but some of the things that are nearly universal...

1. Depending on the horsepower of the SBC. Same horsepower I would imagine you'd pick up a little speed do to the substantial weight diff between the two. Less horsepower = less speed.
2. Sure - just takes money to make horsepower. Old adage...speed costs...how fast do you wanna' go?
3. I would only guess...not. Different blocks but I'm not really a chevy man.
4. Definitely not. From my memory the BBC has equal port spacing on the eshaust where the SBC has paired the center 2 exhaust ports. At least that's my memory.

[MOWtown]

What's the problem with your BBC?

[red_n_vegas]

I have a knock/ping in the lower front of the motor at low rpm’s can't really hear it the higher the rpm’s the louder it gets it sounds like it is coming from the timing cover area.
So I took the damper off and timing cover and can’t see anything out of the ordinary. One thing that does bug me is the damper looks to be out of round and is hitting the bottom of the boat, also when the rpm’s come up the damper gets worse.

[its all good]

RED,GOING TO SMALL BLOCK WOULD NOT BE TO YOUR BENEFIT FIRST YOU WOULD HAVE TO MAKE SURE YOU HAD A SMALL BLOCK BUILT FOR A JET BOAT WHICH MEANS HIGH RPMS FOR LONG PERIODS OF TIME , SECOND OF ALL YOUR MOUNTS WILL NOT WORK AND YOUR BB MANIFOLDS WILL NOT WORK AND MOST IMPOTATNT WITH YOUR FUEL TANK BE LOCATED IN THE BOW OF THE BOAT YOU NEED THE EXTRA WIEGHT OF A BIG BLOCK TO KEEP THE BOAT BALANCED , NOT TO MENTION ALL THE REST OF MOUNTING CHANGES.. BEST BET TAKE THE MONEY AND REBUILD WHAT YOU HAVE

[red_n_vegas]

Thanks Bob and E502 it looks like it i will try to rebuild the 454 .

[jkpruitt]

I'd pull it out and quick......................and give it to me.