What can I do to get a 305 (898) to preform as good as the old 351 OMC

[vi]

Re: What can I do to get a 305 (898) to preform as good as the old 351 OMC

are you sure a 305 came out?
the 305 wasn't produced until almost a decade after your Belair rolled off the line.

maybe it was a 283.

Howard my bad ... it was a 307 ,still a turd though...

 

[cyclops2]

Re: What can I do to get a 305 (898) to preform as good as the old 351 OMC

My 5.0L ..305 CI in a 2002 (18.5' WL length) Chaparral 186 SSI at 3400 pounds is at 50 mph fast. Hole climb out is about 3 seconds then off to 50 mph.

Caution....the boat is 8' wide with about 18 degree V at stern & it has a very good ride pad. It does growl when floored from a stop then climbs out fast.

Your boat MAY NOT have so much hull area to spread out your weight. If you do not. All bets are off.

 

[Howard Sterndrive]

Re: What can I do to get a 305 (898) to preform as good as the old 351 OMC

Howard my bad ... it was a 307 ,still a turd though...

The 307 was originally, and always has been a lo-compression, low performance, 2bbl economy engine (it was simply a stroked 283). Consequently, it was not a performance, or potential performance, engine.
Whereas the 305, even though it had a smaller bore than the 307, had a longer stroke that makes it more suitable in a boat.
Need the right heads and carburetion, but the 305 is good for boats up to 20 or 21 feet imo.

 

[Tail_Gunner]

Re: What can I do to get a 305 (898) to preform as good as the old 351 OMC

If your talking about a GM 305 there is little that can be done and at that it gets expensive. The core issuse issue are the heads...They are not vortec heads....They have been coined as much but they are not. Nor is the 305 a bad engine its just not a true vortec motor. Heres a question can one marinize a 350 with 305 parts...Bet theres a nice 300 hp 350 out there for a 1000 or so...

 

[starsnstripers]

Re: What can I do to get a 305 (898) to preform as good as the old 351 OMC

This is a start, read this, gets 260 hp out of a 305=350 hp copy and paste http://boston.craigslist.org/nos/boa/2713512465.html

 

[scoflaw]

Re: What can I do to get a 305 (898) to preform as good as the old 351 OMC

If your talking about a GM 305 there is little that can be done and at that it gets expensive. The core issuse issue are the heads...They are not vortec heads....They have been coined as much but they are not. Nor is the 305 a bad engine its just not a true vortec motor. Heres a question can one marinize a 350 with 305 parts...Bet theres a nice 300 hp 350 out there for a 1000 or so...

How did you come up with this statement? If it looks like a duck, quacks like a duck, it's a duck.

 

[joewithaboat]

Re: What can I do to get a 305 (898) to preform as good as the old 351 OMC

I think what he means is that there were 305's that were referred to as vortec but were very different from the 350 vortec's. The 305 heads are very different and don't give the same power increases as the famous 350 versions.

 

[scoflaw]

Re: What can I do to get a 305 (898) to preform as good as the old 351 OMC

I think what he means is that there were 305's that were referred to as vortec but were very different from the 350 vortec's. The 305 heads are very different and don't give the same power increases as the famous 350 versions.

Please elaborate on how the 305 head is very different from the 350, besides the valves being a bit smaller.

 

[Bondo]

Re: What can I do to get a 305 (898) to preform as good as the old 351 OMC

Please elaborate on how the 305 head is very different from the 350, besides the valves being a bit smaller.

Ayuh,... They're Not fast-burn(aka; Vortec) at all...
They're the traditional D shape combustion chambers...

Have a read Here.... post # 478

 

[joewithaboat]

Re: What can I do to get a 305 (898) to preform as good as the old 351 OMC

Please elaborate on how the 305 head is very different from the 350, besides the valves being a bit smaller.

Chamber is different shape and smaller, 58 cc i believe. Intake port is smaller and has some type of bump in it apparently, exhaust port is slightly different/ smaller. Lastly valves are smaller with different cut in the bowls under the seats. I have never had a vortec 305 head in my possession but have seen pictures and info on the web while researching the 350 vortec heads.