Here’s my build of a marine engine 305. If you guys haven’t seen one then jump on in and check it out. Chevy built these engines specially for boats. Some say they will out live cars if you use them. They call this one the black scorpion. I’ll update as I go

Camel hump heads is what you want. Only thing is they aren’t aluminum but that’s ok for what I’m doing.

Head numbers

Here’s my casting numbers on the block

 

Does anyone have any tips on what can be used if the sand blaster won’t work all the way. I’ve tried the sand blaster and pressure washer. But still have blemishes

 

That’s what my thermostat housing looks like. The engine is cooled through the exhaust ports it’s very interesting. I’m more a fan of the 305 because of the cylinder walls being a lot thicker than the 350s but they are both good engines.

 

Before picture

 

I’m trying to figure out what I’m going to do about the rust inside there which hasn’t really ate anything up yet but nevertheless it’s there and it needs to be dealt with before something eats my engine away any ideas

 

That's just rusty hot garbage - essentially a mild upgrade to the LB9. Can't give them away. Just pickup a Vortec 350 that's worth your time.

GD

 

Those heads (081 casting) are in fact LB9 heads. The exact same part # as the 305 TPI motors had from 87-92. They aren't "camel hump" ones like the ones from the 60s & 70s, like 186, 462, 492, 041, etc.; or the earlier ones like 461 (that didn't have the bolt holes for accessories). Decent enough heads for their day but not the same. The casting date (J126) means that they were cast on the 12th day of the Jth month, (the 10th, October) in a year ending in 6; most likely 86. The boat it was installed in was probably a 87 year model.

305s don't have thicker cylinder walls than 350s. They're about the same, in that time frame. Thinner than others from other time frames.

That intake isn't native to that motor. It's an Edelbrock Performer. That never came on Merc motors that I'm aware of. In fact it puts the carb at an awkward angle, for a boat; the correct Merc intake would have the carb parallel to the block mounting surface, because in a boat, the motor sits level rather than being tilted back like it is in a car. I have one out in my garage I could take a pic of to show you if you don't believe me. The one I have is a Merc 888 (188 HP Frod 302 2-bbl) but the principle is identical. The original one was probably cast-iron, not aluminum like that one.

The cooling system in a boat pretty much ALWAYS dumps water into the exhaust. That's just how it's done. In fact the exh manifolds have water jackets and are cooled by the water exiting the engine before it passes into those elbows on top of them. The thermostat isn't just open/closed like it is in a car; in a boat motor with seawater cooling like that one, when its closed the water goes one way, when open it goes another, rather than the flow just being blocked. There are 2 water pumps; one in the stern drive, and one on the front of the block just like in a car. The thermostat operates at a MUCH lower temperature, something around 140 - 150°. In a boat with a closed cooling system, there's antifreeze in the motor, a "heat exchanger" that the coolant goes through and the seawater cools, and the seawater is pumped from the stern drive through the HE and from there to the manifolds and elbows.

I happen to have a Clymer's for Merc engines up to about 87, which is about when I bought it.

There's nothing particularly different about a boat motor compared to a car one, regardless of what you may have "heard". That Merc 228 or 230, I forget what Merc called the HP in 87, is basically the same motor as the LB9, with possibly a different cam and of course all the marine cooling system external oddities and whatnot, like the distributor without vacuum advance, the fuel pump that only puts out like ½psi, the carb with the weird vents, and so on. It's still just a 305. The same underneath those external parts as about any other 305 from the same time frame, except that it has the better heads (not the swirl-port TBI ones). Just as futile to spend money on, thinking you're going to make it competitive, as any other 305 that anybody else has ever come up with that idea over; and just as destined to disappoint.

 

Well, that went in an unexpected direction, huh?

 

Based on the specs that a plain old Google search yields, it's essentially the same performance as the LB9. I had a nice rusty-jacket LB9 sitting here for months that had roller tip rockers, all maintenance done, and Dyno sheets showing 185 rear wheel HP in my car. I offered it up for FREE and no takers. It went to scrap.

305's just aren't worth anyone's time. My 97 Vortec 350 with stock heads, stock rotating assembly, valve train and cam upgrades makes near 400 HP (325 wheel though my 700R). That's on stock iron Vortec heads.

That rusty 305 from a boat is just garbage. Sorry.

GD

 

An interesting 36 post foray into this site, OP.

 

I noticed this too! The guy went wild!!
He joined TGO yesterday and made 36 posts on day 1, often times replying to threads that had been dead for over a decade!

 

On every forum I am a member of, I have seen a massive surge in people joining and on their first post they reply to decade old threads. WTF is going on?

 

Yeah seems like lots of the forums these days pop up a "ask a question" window to new users, to encourage them to participate. I'm guessing this one must be sorting posts in forward chronological order instead of reverse, so old posts appear at the top of their queries instead of newer. While it's always good to see new blood come into the hobby, the disorganized blabbermouth does get kind of annoying at times.

 

Other than the Corona quarantine putting more people on the interwebz than usual, and many of them never having previously posted on any 'forum' formatted site, and with zero knowledge of how they work, at least for OP, there's this:


https://www.thirdgen.org/forums/diy-...ml#post6387673

 

A 305 being secretly better than a 350 is evidence of early onset "dunning krueger syndrome",the only cure is education.
Generally people making claims that make no sense is telling,the story it tells isn't a pretty one.math is your friend,not your enemy.

The silliness regarding a 305 being thicker has absolutely no merit and is ridiculous tbh.you should ponder why there are millions 350's in existence that make great power .305s,not so much.
perhaps ponder why 3/4 of people who have a 305 ,remove it to install a 350 in its place.it isn't anything special and would be o.k but underwhelming for a third gen.

it will not be spectacular ,it will not be better than a similar 350.its basic math,physics and intelligence

 

if it was free and you have no engine,you did well.if you paid for it someone right now is laughing and thanking god they had an engine hoist and an unwitting buyer .