Frequently Asked Questions
Dear 350marineengines.com I have a 350 marine engine with 260 horse power and I
see you state your 350 with 300 horse power uses less fuel while
producing more power. The question I have is what kind of changes or
modifications do I need to do to install your 300 horse 350
300 horse 350/ 5.7 marine engine is the exact same engine
castings you have now the only difference is by years. If yours is a
1996 260 horse order a 1996 with 300 horse. At Marine Engines we beef
up the inside of the 260 horse 350/5.7 engine to make more horse power
using much stronger higher compression pistons plus a bigger camshaft
profile also known as lift and deration and larger stainless valves. You
can also use 87 octane fuel. Increase your interested we can make your
260 horse in to 350 horse 350/5.7 still all your parts bolt right on an
fit in to your original engine mountings.
Question: I have a 305/5.0 in my boat now what kind of
modifications do I need to do to install a 350/5.7 I need to know will my
intake manifold work, valve covers, oil pan, timing cover, exhaust
manifolds and ignition work.
Yes to all your questions every part on your 305/5.0 will
bolt right on to our 350/5.7 engines. This also includes your flywheel,
harmonic balancer, power steering, fuel system and alternator trust us
to get you the right engine. I would sagest 300 horse power 350 our are
the most fuel efficient.
Question: I want to up grade to more horse power will my
out drive handle more horse power.
If your original engine was a 260 horse 350 your out drive
will handle up to 350 horse power even more depends on your out drive
call us but to be safe 350 horse power no problem.
If you have a 454/7.4 your out drive will handle up to 450
horse power and higher depends on out drive just call but 450 is okay.
Question: I have a 1999 350/5.7 mercruiser I see you have 383
strokers 350 and 400 horse power. Can I install one of your 350 horse
383 stroker where my factory 350/5.7 was.
Yes you can install a 383 stroker in place where you have
your original factory 350/5.7 without making any modifications. We have
many different 383 strokers and one of the problems is in 1986 350
changed its rear main seal to an outside one piece seal but the 383
takes a 400 crankshaft and there has never been a 400 one piece seal
crankshaft from the factory. Our 383 has brand new design crankshaft
that works with one piece seals this way you original flywheel will bolt
right on. In the past to put a stroker in a late model 350 application
required replacing the flywheel, oil pan.
Question: I have a 350 with 260 horse you say in your website the
300 horse uses less fuel but has more horse power how can this be.
Your original factory marine engine has low horse power
and torque because its has low compression and has a small profile
camshaft. We change the compression ratio from 8.5 to 1 to 9.5 to 1 and a
large camshaft profile the two together increases horse power and torque
with less effort or lees throttle needed. I know this for a fact I have
tested this myself and all the new engines made now of days from every
manufacture build their engine with 9.5 to 1 or higher. Me I like my
engines 10 to 1 ratio just use 92 octane on 10 to 1.
Question: I have a 1994 454 with 330 horse power and its a slug in
the water and I cant keep fuel in it is there a way to improve on both.
Absolutely we have a 454 with 420 horse power that will
use much less fuel and at the same time get you on plane much quicker.
Example if your boat travels 20 knots and the rpms are 3,000 you probably
have your throttle lever set over half way. With our 454 425 horse same
speed same rpms but the throttle lever position will be under half way.
My 1994 454 350 horse SEA RAY from the factory used so much fuel we did
not boat much and to make thing worse I was told from the dealer I
bought it from the boat would do over 55 MPH well I could never get it
past 50 MPH In 1995 I took the engine out and put in high compression
dome pistons to make my 454 425 horse power. Now I can go 65 MPH maybe
more but my wife start yelling. Also instead of using half a tank of
fuel I now use quarter tank. You to will have similar results including
your wife say slow down or let me out. My personal story call me I tell
you all about it.