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can anyone recommend inexpensive engin rebuilder
- Thread starter stang32
- Start date
Never under any circumstances would I even consider using an automotive gas engine in any boat. You get what you pay for. Ron brings up excellent points when it comes to ignition and fume protections afforded marinzed engines.
Bill
Bill
Tch! Tch! Tch!
Exactly where do you think these marine engines come from? You think GM has a special line that puts together marine engines for Merc or Crusader?
There isn't a heck of a lot internally between auto and marine. Most of the stuff are the 'bolt-on' parts. And the marine bolt-on parts are the same as the automotive except for the so called 'Spark Protection'. 95% of y'all haven't disassembled starters or alternators so you don't actually know what and how they're made. Most starters are already spark protected. They don't want their brushes exposed to debris so they cover them with bands or covers. Some add a gasket under a cover. The same idea goes for alternators. Delco simply adds SS screens to the front and back. Mechanical fuel pumps DO have a line added to direct fuel to the carb in the event of a ruptured diaphram.
Exactly where do you think these marine engines come from? You think GM has a special line that puts together marine engines for Merc or Crusader?
There isn't a heck of a lot internally between auto and marine. Most of the stuff are the 'bolt-on' parts. And the marine bolt-on parts are the same as the automotive except for the so called 'Spark Protection'. 95% of y'all haven't disassembled starters or alternators so you don't actually know what and how they're made. Most starters are already spark protected. They don't want their brushes exposed to debris so they cover them with bands or covers. Some add a gasket under a cover. The same idea goes for alternators. Delco simply adds SS screens to the front and back. Mechanical fuel pumps DO have a line added to direct fuel to the carb in the event of a ruptured diaphram.
quote:
Originally posted by jtybt15
Tch! Tch! Tch!
Exactly where do you think these marine engines come from? You think GM has a special line that puts together marine engines for Merc or Crusader?
There isn't a heck of a lot internally between auto and marine. Most of the stuff are the 'bolt-on' parts. And the marine bolt-on parts are the same as the automotive except for the so called 'Spark Protection'. 95% of y'all haven't disassembled starters or alternators so you don't actually know what and how they're made. Most starters are already spark protected. They don't want their brushes exposed to debris so they cover them with bands or covers. Some add a gasket under a cover. The same idea goes for alternators. Delco simply adds SS screens to the front and back. Mechanical fuel pumps DO have a line added to direct fuel to the carb in the event of a ruptured diaphram.
Charlie yes they start life as a GM block but that is where the differences start and stop. Not everyone who asks where can I get a cheap replacement motor understands or remembers the ignition and fuel vapor protections needed when building the marine version.
Is an automotive engine a drop in replacement for a boat? Not even close.
Bill
quote:
Originally posted by jtybt15
Exactly where do you think these marine engines come from? You think GM has a special line that puts together marine engines for Merc or Crusader? ............
I don't think anyone suggested that. The marine engine builders (Mercruiser, Volvo, etc.) buy the engines and marinize them. They are the ones with the "special line".
They replace or add parts so the engines meet safety requirements for boats and so they perform better in marine service.
Guess what! ALL Carbs vent to air...and the mechanical fuel pump is the ONLY marine specifically manufactured part.
and other than head gasket, freeze plugs and cam, what do you think is marine specific. The fuel injected engines may even have the same cam as the auto.
Another thing I've mentioned before, the piston is the full dish type straight off the line as designed for the SMOG controlled auto engines to pass EPA Regs.
and other than head gasket, freeze plugs and cam, what do you think is marine specific. The fuel injected engines may even have the same cam as the auto.
Another thing I've mentioned before, the piston is the full dish type straight off the line as designed for the SMOG controlled auto engines to pass EPA Regs.
Charlie, As one of the long time members here I recall a series of posts by George criticizing the use of auto blocks in boats. Quality of pistons/rods, etc., was one thing he mentioned, but also tolerances given that boat motors basically have to run all day at what in a car would be first gear at higher RPMs. I'm not an engine builder and have never ripped down a marine block next to a auto block, but I sure would like some hard data on what the real differences are between the 2....had to chip in here...
Keith,
I think it's pretty well accepted that marine engines come from auto manufacturers. One of Geo's favorite sayings was Merc's foundry was right next to their refinery. I bet even Crusader uses stock auto engines with marine head gaskets and freeze plugs. They probably even use the auto roller cams, unlike the flat tappet hydraulic days. Only 'aftermarket' or private/professional engine builders given specific instructions use forged crank, connecting rods or pistons. Crankshafts and connecting rods receive most of their stress from the higher RPM's of race engines. These stock cast parts work fine for a WOT of 5000 RPM. Most (V8)engines wouldn't last long if run at their max RPM anyway. There's just too much reciprocating weight. 4 and 6 cylinder engines have much less weight and can run at higher RPM's.
I think it's pretty well accepted that marine engines come from auto manufacturers. One of Geo's favorite sayings was Merc's foundry was right next to their refinery. I bet even Crusader uses stock auto engines with marine head gaskets and freeze plugs. They probably even use the auto roller cams, unlike the flat tappet hydraulic days. Only 'aftermarket' or private/professional engine builders given specific instructions use forged crank, connecting rods or pistons. Crankshafts and connecting rods receive most of their stress from the higher RPM's of race engines. These stock cast parts work fine for a WOT of 5000 RPM. Most (V8)engines wouldn't last long if run at their max RPM anyway. There's just too much reciprocating weight. 4 and 6 cylinder engines have much less weight and can run at higher RPM's.
- Joined
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quote:
Originally posted by rawidman
quote:
Originally posted by Pa Mikee
There's not a big difference in GM gas car/truck engines vs a marine long/short block. The freeze out plugs and the camshaft come to mind. The other difference is the color of paint.
The cam is probably important.
All the electrical and fuel system parts are different. According to a televised factory tour of one of the marine engine plants I once saw, they make over 500 changes to marinize a GM block. Paint is only one of these.
I think I would stick with a marinized engine for a boat just to be on the safe side.
I bet you buy the undercoating when you get a new car too.
ALL Merc engine specs are EXACTLY the same as GM. Get a Merc service manual(easiest to get) and compare it to GM. If you want to find out so bad, do the work. Then report back here.
I've built 6 marine engines but only one(the first) was a stock 350. It's not worth going thru the trouble and expense for stock power.
I've built 6 marine engines but only one(the first) was a stock 350. It's not worth going thru the trouble and expense for stock power.
- Joined
- Apr 12, 2006
- RO Number
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quote:
Originally posted by keith2
OK, I'm going to push you.... you say the specs are the same... have you measured them? George would suggest that the clearances were dif fferent between marine and auto engines..... yes again im a troll
Who is George and why do we care what he suggests?
Did George measure the tolerances?
Do you think there would be any particular reason tear down an engine to enlarge the bore or stroke from an engine leaving the GM factory? How about a reason for changing the ring gap or lifter clearances?
I'll know better than to answer any of your questions in the future
I'll know better than to answer any of your questions in the future
Jamie 10017
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- 45
The only difference in the Gm engine from mercruiser and a Gm car engine is the Cam, head gaskets and freeze plugs, every part in the engine has Gm part numbers on them including the pistons. On the counter rotation engine- the camshafts are different,and they have timing gears not chain drives but still turn the same direction as the standard engine but different firing order and left and right side pistons are swapped (most of the time) but still Gm pistons. Go to NAPA and ask for a set of lifters for a BBC marine engine they are the same part number as a Street engine . Go buy Mercruiser lifters they are re-boxed GM lifters. Other than minor bolt on externals and camshafts they are the same engines. The short blocks are shipped to mercruiser so that they can assembled with marine head gaskets. I have 2 Gm 454 Mercruiser in the shop as of today. One of them is a mercruiser rebuilt, Yes I measured all the clearances, they have gm 781 casting cylinder heads Gm valves and rocker arms and cast iron oval port intake with GM stamped all over it, the block is the same. Mercruiser doesn't build engines they don't even rebuild engines a outside company does it for them, Even the water pumps are Gm. And yes I do this for a living for over 35 yrs. They are all built the same because Mercruiser has no idea what company is going to buy engines to install in there boat sea ray wellcraft bayliner are all the same I don't know where you get your information from but believe what you will, Jamie Wheatley -Wheatley Racing Engines Richmond Va.
Ayuh! Some people just believe marine engines are some special concoction or magical assembly of 'marine' manufactured parts.
some years back, marine engines assemblies were recommended to have forged pistons, cranks and connecting rods. These parts were standard automotive race parts.
As mentioned above, and what I've been saying for 10+ years, There is very little difference between auto and marine parts. Someone is sure to disagree by bringing up the electrical parts but I'll describe again, for the fiftieth time, the very slight difference if someone wants to know.
some years back, marine engines assemblies were recommended to have forged pistons, cranks and connecting rods. These parts were standard automotive race parts.
As mentioned above, and what I've been saying for 10+ years, There is very little difference between auto and marine parts. Someone is sure to disagree by bringing up the electrical parts but I'll describe again, for the fiftieth time, the very slight difference if someone wants to know.
quote:
Originally posted by jtybt15
There is very little difference between auto and marine parts. Someone is sure to disagree by bringing up the electrical parts but I'll describe again, for the fiftieth time, the very slight difference if someone wants to know.
Can you say "Boom" ?
It's a real shame when people who don't know any better come to a web forum for information and get bad information that could harm them.
Ron,
Have you ever taken one of those parts apart to see the difference. I have. Some of the differences are close to being a joke...such as Ford starters having a large hose clamp holding the linkage cover down and auto doesn't.
Have you ever taken one of those parts apart to see the difference. I have. Some of the differences are close to being a joke...such as Ford starters having a large hose clamp holding the linkage cover down and auto doesn't.