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View Full Version : MARINE VS AUTO BLOCK DIFFERANCE



Mike R.
05-08-2002, 09:05 PM
I have a 1977 searay model 200 sr with the Mercruiser 228 305 C.I.D. the previous owner allowed it to freeze the ex. manifolds and block + ?'s anyway is it possible to use the marine pistons cam heads lifters etc. in a chevy 305 auto block with proper machining or is there a differance in the blocks? also is this a unreliable procedure?

croozertoo
05-09-2002, 07:38 PM
"There are lots of differences when engines are "marinized", but the blocks themselves are nearly always basic automotive castings. In the GM small block, the 4-bolt main version of the 350 is preferable, but only slightly. The 305 isn't machined with a factory 4-bolt, but that's not a major issue.

Assuming your frozen block was not bored over, you'll need to find a donor block with up-to-spec original bores. Not easy to find in a junkyard, so you may want to consider boring a good donor 305 block .030" over and fitting new pistons. You'll need new rings in either case. Most engine yards will want to sell you a short block anyway, so you may not have to worry about fitting your crank to it. You may want to consider upgrading to a 350 long block - it's cheap horsepower and manifolds, electricals, accessories, etc. should bolt right up.

The reliability factor is determined by how good the machinist and engine assembler are (and eventually the operator, too!) If you shop carefully, you can put together a very good marine engine for much less than a new one.

"

Mike R.
05-09-2002, 08:12 PM
" Ok well lets see, are the pistons and heads marine specific? if not then a good quality 350 long block fitted with manifolds intake and exhaust and all the other goodies is all thats needed? on the other hand if the heads and pistons are specific to marine use then a donor block which has been line bored etc. could use the pistons also the cam. Which goes back to the 350 long block, I would need to install the nmarine cam from 305 or if needed a new cam? oris the 305 and 350 cam differant lift / duration?
Thanks for the help I am cheap and certified engine building mid 80's but no experiance on marine application. i would get a Very good machinist to do the work but I need to know whats up.........Thanks again Mike "

bondo
05-10-2002, 06:12 AM
" mike,
Block is the same, change to Brass freeze plugs...
Heads, No difference.
Pistons, No diff....
the cam on a "crate" motor will have to be up-graded to a "RV" or "marine" cam....Low-end torque is what you want, Not high RPM horsepower..


the 350cid is the best way to go, All your "goodies" fit perfectly, you'll need to retune, rejet the carb. though... "

kim boehm
05-10-2002, 07:43 PM
" Do not know about GM but Chrysler marine blocks were cast with a slightly higher nickel content to impede corrosion. Also we have to assume this is a standard rotation engine as auto engines do not come in counter rotating versions. Sometimes there were diffs in the oil pans and sumps as marine engines are typically installed at a slight down angle. The pans themselves were sometimes cast iron not stamped tin so they would hold up better. But generally speaking you can swap them out. Good luck and let us know when you are 100% again, Kim "

Mike R.
05-13-2002, 04:43 PM
Thanks for the info I have researched every possible moment I've had and am working on a 327 so the ole barge is gonna have some "class"

Thanks again

Bruce Libey
05-21-2002, 10:33 PM
I have twin 1996 Johnson 150's(salt water). The trim must have a short in it because sometimes it wont trim up and less often it wont trim down. Sometimes it effects both engines sometimes only one. I have tightened all the screws and switched the terminals on the engines to see if one is bad. Still the problem continues. Any thoughts?

JOHN CAMERON
06-16-2002, 01:31 PM
" 35 HP FORCE TROUBLES.I HAVE A LOW HR 1990 MOTOR BUT ITS GOT A HOLE THE SIZE OF A PENCIL HEAD AND ~0.120" DEEP IN THE CYL PROBABLY FROM THE WRIST PIN ? DOES ANYONE HAVE ANY IDEAS ON HOW I MIGHT REPAIR, ANY INFO WOULD BE GREATLY APPRECIATED....THX JOHN "

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apak
05-15-2006, 09:50 PM
My new rebuilt motor 4.3 6cyl merc 190 hp will only top out at 3900 rpm runs great. but shouldn't the motor run up to 4800 rpm max? the mechanic installed an automotive block. would that make the difference in the power? does the cam have anything to do with the loss of power.
my boat should power up to 4800 easy...thankyou for any help... have spent a lot of money }and would like the extra speed.

NICK MINARCIK
05-25-2006, 07:27 PM
I HAVE A 1979 26 FOOT CENTURY WITH A 228 ENGINE. WILL A 350 CHEVY ENGINE BOLT UP TO MY OUTDRIVE WITHOUT ANY CHANGES. SHOULD I REPLACE THE FREEZE PLUGS WITH BRASS ONES.IS THERE ANYTHING ELSE I SHOULD KNOW.