1999 Bayliner 5.7 mercruiser caburetor/prop questions

[CatriderF7]

I have a 99 Bayliner 2050 with the 5.7L and like everyone else i have a long list of things I want to do with it before summer along with all the regular maintenance. Performance-wise it runs great. Has a 2bbl carb and a 21p stainless prop it runs low 50s (mph) on gps. I know a big and easy performance mod on older cars is upgrading to a 4bbl carb. But i keep seeing posts where people say it doesnt even make a noticable difference on boats. I also saw someone claim it takes over 300hp to run a prop of my size. I dont know what im running for rpms cause my tach didnt work last year so i guess that makes it a little unknown when it comes to whether the prop is running what it should be.

What I was really looking at doing was replacing my intake and carb with a 4bbl. I can get an almost new edelbrock torker intake for $50 and a 4 bbl rebuilt carb for $300. But will it make any difference with the stock exhaust system? Im just looking for more top end and maybe more midrange performance

 

[thumpar]

Re: 1999 Bayliner 5.7 mercruiser caburetor/prop questions

Get a working tach and see where you are at. It takes a very large increase in power to gain just a little speed.

 

[Don S]

Re: 1999 Bayliner 5.7 mercruiser caburetor/prop questions

But i keep seeing posts where people say it doesnt even make a noticable difference on boats. I also saw someone claim it takes over 300hp to run a prop of my size. I dont know what im running for rpms cause my tach didnt work last year so i guess that makes it a little unknown when it comes to whether the prop is running what it should be.

Just be careful what you read. So many threads that people quote are old news and/or completely wrong information. But that doesn't stop people from reading or believing it.

The most important tool you need is a working, accurate, tach.

Exhaust system is NOT your biggest problem.

The difference between a 2 and 4 bbl carbs is noticeable for most people.

After all that, a 21 pitch prop is not that uncommon, but to find out if that is enough or too much you need information. RPM. speed, pitch of present prop, geaer ratio, etc. There is also a prop forum here at iboats with people with all sorts of prop calculators and ideas for props.

 

[Bondo]

Re: 1999 Bayliner 5.7 mercruiser caburetor/prop questions

Just be careful what you read. So many threads that people quote are old news and/or completely wrong information. But that doesn't stop people from reading or believing it.

The most important tool you need is a working, accurate, tach.

Exhaust system is NOT your biggest problem.

The difference between a 2 and 4 bbl carbs is noticeable for most people.

After all that, a 21 pitch prop is not that uncommon, but to find out if that is enough or too much you need information. RPM. speed, pitch of present prop, geaer ratio, etc. There is also a prop forum here at iboats with people with all sorts of prop calculators and ideas for props.

Ayuh,.... Generally speakin' it's a 20 hp kick in the pants....

'n I agree, havin' No Tach is flyin' Blind...

 

[CatriderF7]

Re: 1999 Bayliner 5.7 mercruiser caburetor/prop questions

Yeah Ill get the tack working and go from there as far as the prop goes. But I think ill pickup the 4bbl and do that. I couldnt imagine why it wouldnt be a noticable increase in power. I actually found a Rochester quadrajet thats almost new locally for $125. For that price its worth it to try it

 

[achris]

Re: 1999 Bayliner 5.7 mercruiser caburetor/prop questions

... and a 21p stainless prop it runs low 50s (mph) on gps.... .... I also saw someone claim it takes over 300hp to run a prop of my size.

Poppy-****!!! I had a 21" prop on the previous engine (180hp 4.3 V6). Ran 4900 RPM at about 39 knots....

Yeah Ill get the tack working and go from there as far as the prop goes. But I think ill pickup the 4bbl and do that. I couldnt imagine why it wouldnt be a noticable increase in power. I actually found a Rochester quadrajet thats almost new locally for $125. For that price its worth it to try it

It MUST be a marine carb, not an automotive carb!!!!!

 

[FreeBeeTony]

Re: 1999 Bayliner 5.7 mercruiser caburetor/prop questions

Try some Vortec heads if you're gonna replace the intake.......

 

[CatriderF7]

Re: 1999 Bayliner 5.7 mercruiser caburetor/prop questions

I want to do vortec heads but I really dont want to tear the engine that far apart. I have seats to get redone and some electircal issues to fix, stereo, extra battery to install this year. Im hoping to rebuild the engine with vortec heads next fall/winter. I have been looking around last night and this morning and have decided not to buy the carb i was looking at. Id rather not deal with possible headaches

 

[FreeBeeTony]

Re: 1999 Bayliner 5.7 mercruiser caburetor/prop questions

Remember, if you're gonna replace the heads at a later time......don't change the intake now.
The vortec heads require a matching vortec intake....

 

[NHGuy]

Re: 1999 Bayliner 5.7 mercruiser caburetor/prop questions

I'd do the tach too. Then do the intake & carb. Then see if you need a different prop.
Vortec heads are nice but they are a lot more cost than you have in mind for the carb. Plus the car stuff is easier to do, and can work with the heads later if you get a different intake manifold.