Hp 500 carb setup help
09-03-2014, 11:33 AM
#21
Registered
iTrader: (3)
Guess what I am saying overall, is generally working on the fuel side of things, is of greater change, than the air side of things.
Although in the world of carburetors, stock holleys gets looked at like they are always able to be improved on. You tell a guy who spent 3 times as much for his custom carb, that a stock holley would probably work better, he will usually tell you otherwise. IMO, holley has been manufacturing carb's for a very long time, and the aftermarket guys have been modding them for a long time as well. Some for the better, but mostly for the worst. The 80443 carb, came with that jet combo for a reason, they just didnt say "umm, lets throw these in here and see what happens''. They know people want to bolt a carb on and run the boat.
RMBUILDER pretty much summed up what I been trying to say, in 1 post lol. Put the carb back to stock and run it. Adjust from there. The idea of just throwing the jets that came from your HP500 old carbs, thinking that the engine will be fueled like it was, doesnt apply.
As far as reading plugs, for years I have been told by guys to look for a coffee colored porcelin on the plugs. IMO, that statement is incorrect, as is any reading you may take, after going wot, coming back to idle, and letting it idle for a bit before shutting down. Pulling plugs after idling back to the launch ramp, is worthless. That tells you pretty much nothing.
When you look at modern fuel injection, the great thing about it, is that it can maintain a clean steady fuel mixture, at all throttle positions, all RPM points, and all load conditions. It does this via feedback in nanoseconds, and can constantly correct itself. To attempt to get within a mile of this, using a carburetor, you also need feedback as the tuner. A carb will never be as good as EFI in this area, for alot of reasons. But, IMO, the feedback from pulling a spark plug here and there, simply will not get you within a mile. At least not to the point of "oh, i need to change my high speed bleeds .002, that should do it", or "Im a tad rich at 3300rpm, but a tad lean at 3600RPM, so let me change the PCVR by .007". Without a doubt, reading plugs is still mandatory, and can save you from meltdown mode.
But, think of it like this. You think you're wife is screwing around on you, but have no proof. You can hire a private detective, to check on here whereabouts randomly at 8am, 12pm, 5pm, and 10pm. However, theres still a good chance, she might be bent over a leather couch taking it like a champ, at 2pm somewhere. Best bet is hire a detective to stay with her from 8am-10pm to get your answer. Having a 02 sensor at least will monitor the fueling from idle to wot, where you can watch it live.
Last edited by MILD THUNDER; 09-03-2014 at 11:36 AM.
09-03-2014, 08:11 PM
#23
Registered
Mild Thunder are the power valves different front to back?
Put it back to how it was shipped. It should have had 96 jets in secondary? Your old carbs were smaller and therefore won't meter fuel like the new ones. Smaller carbs like smaller jets. As for the fuel leaking, loose bowl screws can lead to a carb leaking internally. If you want to block the rear pv on the 850 marine carb you'd want to jet up about 6 sizes in the rear. Put it back to how it was shipped , go run it, and report back.
09-04-2014, 05:44 AM
#24
Gold Member
Ok. Put the secondary metering block that came with it back on with 96 jets and put the jets it came with back in the primary. Cold start it lights right off. When I rev it at the dock it sounds very strong and has no hesitation. Gets on plane nice and fast doesn't loose any rpm. Once up and cruising at 3300 or so it will drop down to 3100 then come back up few seconds later. I get the same rpm drop from wherever I am. So at 4k it will drop to 3800 or so. And back. I did go wide open once it comes in and it will bog then start to pull then bog again. Float levels are correct. Gona chnage fuel filter for the hell of it today
09-04-2014, 07:23 AM
#26
Can you actually feel a loss of power when this happens, or is it just indicated by the tach? In addition to fuel supply issues, it's also possible that some junk got into a passage with all the tinkering that was going on with the carb.
09-04-2014, 07:27 AM
#27
Went back and looked at your original post, and I'm not clear if this is a single or twin engine application. Is this the 353 in your avitar? If so, did you replace both carbs, or just one of them? If you did both, and the surge issue is happening with both of them, then it sounds like it is probably fuel supply related.
09-04-2014, 08:04 AM
#29
yes, can feel it in the boat. dont have fuel psi gauges. one carb is new, surge is only on one motor with new carb. have been having problems all year with this motor. im gona change the filters tonite and re try. i have stock metal hp500 feed lines to carbs, so no inline guages. i may make up some lines with guages.
