What is the difference between motors

[trucker28]

Hello all
I was wondering what the difference of a Chevy 305 block in a car and a 305 block in a boat is there a difference or can I use a block out of a car to replace my cracked block in my boat thanks mike

 

[MikDee]

Re: What is the difference between motors

Yes, & No, It is the same, But the marine version has Stainless Steel head gaskets, a S.S. back plate on the water pump, a sealed carburetor, & fuel pump, (no venting, or boom!) a sealed Distributor, Starter, & Alternator (No sparks!), Oh yeah, you might need brass feeeze out plugs and I think that's it? Others may chime in to add to this list, but if you can bolt these up to your block, you'd be fine!

 

[Bondo]

Re: What is the difference between motors

Hello all
I was wondering what the difference of a Chevy 305 block in a car and a 305 block in a boat is there a difference or can I use a block out of a car to replace my cracked block in my boat thanks mike

Ayuh,.... The actual Block castin' is the Same, so long as the block castin' number is the same, or if they're of the same vintage,....

 

[trucker28]

Re: What is the difference between motors

Ok thanks so let's say I want to rebuild it right from the piston up with all new gaskets and lot of part from the motor in the boat now I basically want to start from scratch with the block
And bondo what do you mean block castin thanks

 

[trucker28]

Re: What is the difference between motors

We're do I find this castin number can I find it with the motor still in the boat

 

[1Zorro1]

Re: What is the difference between motors

We're do I find this castin number can I find it with the motor still in the boat

Casting # is on the block driver's side top next to where the trans. bolts on. Would add the marine motor has a stainless steel top ring.

 

[achris]

Re: What is the difference between motors

Just make sure you have brass core plugs (they are not freeze plugs. They are from the casting process, nothing to do with freezing) and that there are tapped holes in the block for the starter-motor to mount to. Most car engines have the starter-motor mounted to the gearbox bell housing, and a lot of car blocks don't have the starter-motor mounting points drilled and tapped.

Chris.......

 

[midcarolina]

Re: What is the difference between motors

Ok thanks so let's say I want to rebuild it right from the piston up with all new gaskets and lot of part from the motor in the boat now I basically want to start from scratch with the block
And bondo what do you mean block castin thanks

I want to verify.....sometimes I can be a little thick. are you talking about using the entire short block from a car, then bolting on your heads and all other marine components?

If that is your intention I would look for a 350 out of a truck, they are very close to marine specs....and I beleive many already have the brass core plugs.

 

[trucker28]

Re: What is the difference between motors

A 350 really I did not no that I just found a cheap 305 and that is what I have in the boat but I can look for a 350 to thank you

 

[achris]

Re: What is the difference between motors

If you can get a 350 from a truck, that is a much better way to go. The externals are just about the same. You might have to change the carb jets and the ignition advance (and without knowing the engine serial number, or at least the year, there is no way of knowing)... The blocks are the same apart from the bore....

Chris.....

 

[JaguarMan]

Re: What is the difference between motors

What about the camshaft profile?

 

[Bondo]

Re: What is the difference between motors

What about the camshaft profile?

Ayuh,.... A truck cam is very close to a Marine grind, No problem,...

 

[trucker28]

Re: What is the difference between motors

You keep saying truck block wouldn't a 350 from a car be the same thing or for some reason are they different

 

[achris]

Re: What is the difference between motors

You keep saying truck block wouldn't a 350 from a car be the same thing or for some reason are they different

Camshaft used in a truck engine is different to a camshaft used in a car engine. Truck engine cam profile is very close to that of marine application, nice flat torque curve... So you're looking for a TRUCK 350, not a car one, unless you plan on using the cam from the dead 305 (yes, they are the same)....

Chris....

 

[trucker28]

Re: What is the difference between motors

Oh ok thanks well if I am going to do the whole motor it would be just as easy to pull the camshaft wouldn't this would be my first motor build so it is all new to me I am thinking if I am going to do it i will try to do it the right way lkl

 

[Alwhite00]

Re: What is the difference between motors

Just make sure you have brass core plugs (they are not freeze plugs. They are from the casting process, nothing to do with freezing) and that there are tapped holes in the block for the starter-motor to mount to. Most car engines have the starter-motor mounted to the gearbox bell housing, and a lot of car blocks don't have the starter-motor mounting points drilled and tapped.

Chris.......

I haven't seen a small block Chevy yet without the starter holes tapped in the block.

 

[midcarolina]

Re: What is the difference between motors

IMO...... If you have never built a motor before I would take the much safer route and find a nice truck 350.... Plus I am not a fan of taking internals ( camshaft ) from one engine and put in another.... the wear on the cam and on the bearing are going to be different.

Don't take this the wrong way....but there has been lots of folks who have tore down a perfectly good engine with good intentions to rebuild, then end up with no near as a good engine as before the tear down......

Of coarse I have no idea of your mechanical skills... if you have the proper tools...etc..... just sayin...

 

[Bondo]

Re: What is the difference between motors

I haven't seen a small block Chevy yet without the starter holes tapped in the block.

Ayuh,.... Agreed, but ya gotta pay attention to the hole Pattern,...

Straight across holes are for the 12" flywheel,...
The Staggered pattern is for the 14" flywheel,....
'n Some, but not all blocks have Both patterns drilled, 'n tapped,...

 

[trucker28]

Re: What is the difference between motors

Lol thanks but I am no stranger to a motor I have done head gaskets jobs before and torn my motorcycle apart and rebuilt it I have just never done a bigger motor so I have a good idea how to do one just not 100 percent so yes I am confederate I can do it.right now i am at the stage to buy block and all the parts

 

[1Zorro1]

Re: What is the difference between motors

Total agreement. I have seen 305 out of who knows what go into a boat and function fine in light duty situation will get you on the water. A factory built motor is generally a tough thing to kill. Do a compression test, look for leaks, does it burn oil get a friend who knows to have a look. what kind of performance are you looking for. On one hand if you are just running around lakes and rivers and like to just idle around your needs will be different than if you wanna go fast a lot and/or go on the ocean. There you cannot skimp period. Running on plane for extended duration does require a strong young motor. A car running down the highway uses very little torque compared to a boat at sustained higher revs keeping a boat on plane. Parts you remove should always be replaced with new parts if they go round and round or up and down. And if the parts are internal tolerances should be measured. My latest motor i started from scratch had a block machined and bought every single internal part fresh from summit actually.