Sorry to bump such an old thread! But there was good information here so I thought I would keep the conversation going here if anyone is willing to entertain it.
Rundown:
Boat was sputtering at 4k, RPM's dropped to 3800, then it would accelerate until 5100 but if I let off it would feel like it was going to die again.
Stock Marine Power 454 with less than 200 hours.
Since posting this originally I updated the carb to the same quadrajet, which was a mistake but the boat was running so poorly and I was at the river almost every weekend last season so I wanted to avoid downtime. This definitely alleviated some of the issues that I was having, I also found that the leads to the fuel pump were a bit janky (carter fuel pump with push on leads) so the fuel pump was cutting out at times, I replaced the fuel pump with the same Carter fuel pump. After fixing those I found that the boat was vapor locking super bad, because a few times leaving the sand bar after a long drive it would die and be a bitch to restart (Cannot tell you how much gas I swallowed and to make matters worse it was always mixed with copenhagen), I know for sure it is vapor lock because if the air cleaner got removed after it died vapor would pour out for a while, but I think another part of the problem is that it is so hot in the engine compartment that it may be vaporizing in the lines.
Now the boat does pretty well, but it definitely still sputters around 4k and when letting off from WOT, just not as bad. The vapor lock issue can be fixed by leaving the hatch open after a drive, but I'd like to avoid that.
So a few questions:
Should I bother having the quadrajet rebuilt, it may only save me like $200 from a holley, if I get a 750 Holley will I need to bring it to someone to have it tuned for the stock 454?
The quadrajet also has a weird choke (which could also be playing into the issues I suppose) See example:
https://www.hemmings.com/magazine/mus/2009/10/The-Lost-Art-of-Choke-Adjustment/2144991.htmlWould the Holley be plug and play or would I need to do something about the choke as well? I know I will need a bore adapter but that part is easy.
Which holley 750 model would you recommend for this set up?
Next: Everything I have ever read about electronic fuel pumps says mount them down low, well mine is mounted off the back of the motor at almost the height of the intake manifold, I would assume relocating this down low would be ideal? Additionally I think the carter pump is pretty weak, so any suggestions for a new electric fuel pump?
The boat came stock with a Delco E.S.T ignition system, can't really find anything regarding the quality of these, and I'm not positive that it is having any issues but It's on my list of things to look at because of the issues I'm having. Any feedback on that?
Last: I have one pretty large blower that vents out the back of the boat, on the opposite side the boat has a air inlet, but I was considering maybe trying to change that setup to help with the vapor lock, one idea was to run a second blower, reverse, to help draw cool air in from the air inlet side while the other side is pumping air out. Another option would be to flip the little intake that the current blower pushes air out of so it is facing forward and cut in new vents on the rear of the boat, similar to what Ultra has, and vent the blower through there. The last idea, which is least ideal, cutting a scoop into the motor cover, obviously thats prime chick in bikini territory and also would involve some upholstery.
