305 to 350???

[5meter]

Hello,

I have a 83 Century 228HP (chevy 305) with a cracked block.
Since I'm replacing the block I thought I might put in a 350 but I don't
know if the Thunderbolt Ignition and carb will interchange.
(or other potential problems)
Would like to hear advise on this.

Thanks

 

[Olds Eddie]

Re: 305 to 350???

I did the same thing several years ago. The heads off the 305 are a little small in breathing capacity. The Carb will probably need recalibrated. Everything should bolt right up. You will need a marine camshaft so you dont have problems with water reversion. You may be able to reuse the one in your oresent engine if it is not warn. I think a truck cam is probably ok though. If you want to increase the efficiency of the engine go with a roller cam and lifters.

 

[mtnrat]

Re: 305 to 350???

Get a longblock and the cam and heads are already there. I assume you were going to anyway. Everything should bolt up. Just make sure you get the correct year, with the right seal. 2 piece I would think for an 83. I made the same change and it was very easy. My 305 had a 2bbl so I switched to a 4 bbl that was good for a 350.

 

[riverjet502]

Re: 305 to 350???

I would go for it... Since you will be looking at different heads go aluminum. I like the Edelbrock aluminum Performer RPM heads. This will shave a bunch of weight off your motor plus the aluminum will disapate heat better then the stock iron heads. Ignition I prefer MSD. Contact Crane cams and be honest with them on how you indend to run your boat. You should walk away with a nice roller cam. Throw on a Eldebrock dual plane Air Gap intake with a holley 650 and you should have at min a solid 300 hp mill running on pump gas...

 

[shift]

Re: 305 to 350???

I did the exact same thing in a 80 Century w/ a 228. I bought the GM Goodwrench 260 hp 350 long block out of Jegs catalog and switched everything over from the 228 and it works great. Engine comes w/ hydraulic cam that peaks at 4800 rpms which is right where you need to be. Everything off the 228 bolts up perfectly and worked like a basic replacement. The only thing I did change was the carburetor. I bought a quadrajet off a Merc 260 from ebay and put it on. It worked like it was made for it. Changed prop from 19 pitch to 21 and boat ran like never before.

 

[jastacey]

Re: 305 to 350???

I'd stay away from alumium head if the boat is operated in salt water, and the alumium intake manifold, they will corrode in no time, but if the boat engine is set-up for a closed cooling system, them go for it.

 

[BigSteve1967]

Re: 305 to 350???

i have a few questions...i would like to do the same thing i have an '88 celebrity 210v with the 305 200hp motor 1 piece rear seal and 2 bbl carb thunderbolt ignition in it the motor is basically gone. now what i was wondering is i have heard time and time again about marine cams and cams in trucks are somewhat similar i have a 1995 chevy tahoe 4wd with the 350 engine in it that the truck itself is just dying around a very very solid motor would i be able to take the motor from the truck and put that in the boat? what would i have to swap from the 305 to the 350? i would guess intake manifold and carb but could i leave the distributor in it seeing as they are both hei ignitions? any help would be greatly appreciated

thanks

Steve

 

[180shabah]

Re: 305 to 350???

Wow riverjet,

That's alot of money for 300hp(heads and cam). The stock merc cam is good for 290-300hp (more with a good intake) when used with vortec heads(much cheaper than aftermarket) and a 4bbl.

 

[180shabah]

Re: 305 to 350???

Steve you need to start your own thread or this will start to get very confusing for folks.

Brief answer to your question though.

Ignition, Fuel system, electrical components are all marine specific. Substitution of auto parts cause explosions.

 

[BigSteve1967]

Re: 305 to 350???

sorry just did that i apologize