holley carb on 460 mercruiser

[lambsgrace]

sorry I am lost been reading the info that deal with rpm's and so I was checking to see if my carb opens up wot and found that the first two set are wide open, and the next set aft are open just a little. should they be open all the way, and not will it effect my power.

I found out that my 5.8 is really a 460 it in a 22.5 bayliner skagit offshore cutty heavy 3650lbs. I didn't think a 460 can be mounted to a merc alpha1, but need to know do I need to change the prop to a diffrent pitch and if so what is the best you recomend. I had a adustable pitch prop 4 blade that ran great, but I drift to close to shore and broke it so I do not know the correct pitch to replace it with tried 15x17 and its not correct had more power with the 4 blade and speed. so I check engine first compression is 150 on all 8. have petronix conversion in proestolite distributor. many diffrent opinions on setting the advacne is there away to set the advance on prestolite distributor. if so need to know please don in some other treads made it seems that it can't be so what do I do it has good spark, compression good is 150 good.

the propulse 4 blade was fast in it it would stand the boat up instant plane have benett trim tabs. the spec sheet recommends 15A4 and I am lost cause I like the way she ran my tach reading 4100 and it should be 4400 to 4600. I don't know rpm with the 4 blade cause tach was disconnected. the 15x17 with know pick up low hole shot I think I did't change the thrush washer is this important does it affect the prop. thank you for any help tuna season comming and realy want her running good

 

[HT32BSX115]

Re: holley carb on 460 mercruiser

Howdy,


I am not sure if you are asking a question or not.

You might reveal a little more info on what you have.......Is it a Mercruiser engine and drive or not? Mercruiser NEVER put a Ford 460 in front of an Alpha drive. (never)

If you actually DO have a Mercruiser drive, It's possible someone cobbled an SEI conversion + Alpha drive to an OMC engine and transom. (Against SEI's recommendations, I might add)


As far as prop pitch, number of blades, etc, you need to have an accurate tach. (period) For best performance, you want the engine to turn around 4600-4800 RPM at Wide-open-Throttle ("WOT")


You also need accurate speed measurement. GPS is the best or at least a calibrated pitot system.

The 460 is capable of about 340hp at that RPM. Mercruiser used to break Alphas running with (330hp) 454's (which is why they developed the Bravo) so be gentle with the drive.


Got any pictures?



Regards,


Rick

 

[lambsgrace]

Re: holley carb on 460 mercruiser

It had a 5.0 I change it to what I thought was a 5.8 with four barrle holly. A year later my friend i bought the motor from tells me its a 460.a friend gave to him no problem on the install and it is a mercruiser motor and outdrive. it had the propulse 4blade adjustable pitch and she ran good but never knew the pitch. broke that prop so tried merc 13.75 x 21 3blade ran ok but took long to plane very fast after trimed out.

I was told i should have 15dia n bayliner did put 5.8 233hp mercs in 22ft skagit offshore recommend 15A4. I don't know what A4 is was told it a 4blade and some say its not. so I tried 15x17 3b and seem to cut into water more and refuse to plane its topping out at 3900-4100 going out with gps for better info

I know that the carb is not fully opening now. I check comp 150 on 8, then wot on carb found that two open all the way, and two back ones do not open very much. notice this today will that be a proplem. can it be adjusted there is a lock set on it. do not know.

 

[lambsgrace]

Re: holley carb on 460 mercruiser

I want to know if should keep the 15x17p and will the carb not opening all the way be causing most of proplem. should i fix or replaced it before changeing the prop