Thread: carb trouble

Tweet

Dont want to sound like a smart ars , but the fuel pressure has to be correct before you can figure anything else out.

Smart ass? I asked you for help :-) Not the other way around.

made a fitting to T it into the line post filter, 8psi.
From what I read Holleys want 4-6, so I guess I need to regulate it.
crap, ohh well guess thats the end of this till November

Thanks,
Drew

just put in a fuel pressure regulator in your fuel line. they are sold everywhere and are pretty cheap.

Drew you never did say what power valve is in it, I think it should be a 6.5 providing you have pretty much normal manifold vacuum, say 13 to 16.

Idle passage plugged - vaccum leak - What rpm is it idleing at now?

6.5 power valve.
Idles at 15.5inch vac
In gear it is 12inch.
Idle is at 700ish (as best as my timing meter can tell me).

I'm offshore now, so I won't be able to proceed any further with this until mid october/november.

My plan at the moment is to get one of my friends to lend me a working 4v carb for a few minutes so I can pinpoint it as definate carb problem.
As I said, despite being very experienced with marine diesels, I'm somewhat of a novice on gas engines, I may be overlooking something simple.

Thanks,
Drew

fuel regulated to >7psi.
Took off intake manifold/carb, resealed everything to assure no air leaks.
No progress.
Also adjusted the secondary butterflies so they are open a little more at idle, theory being that I can close the primaries more assuring idle circuit not transfer circuit is in use.
Used carb cleaner and compressed air in idle air bleeds, took idle screws out for the same treatment.

probably could have bought a new one for all the time/cash I've sunk into this. Might just do that yet.

Drew

I haven't bothered to read all this yet, but start off by turning down your fuel pressure to 3 # to eliminate that as a source of trouble,,, tonite I'll try to get time to read thru your posts to see what you are complaining about and what actions /results you have done/got

borrowed a neighbors 4100 autolite, threw it on the truck.... ran perfect.
I'll screw with this carb today, but I'm thinking it's time to find a new one, I've set everything perfectly 4times... something must be warped or something else is up with it.


thanks everyone for your help,
Drew

You've gone thru everything pretty thorough. The problem must still be in front of you, not fuel pressure if you have regular mechanical pump.
I would have a looksee at the metering block gasket, front bowl. The early 1850's have a crossover tube (internal) for the accelerator pump circuit just above the power valve, this is a little short brass tube with an 'o' ring on each end. You don't have one in your carb, but! the gaskets for that type of metering block are included in the rebuild kit, it has a half-moon notch cut out of it just above the opening for the powervalve well. If you use that gasket with the modern 1850 fuel will run from the accelerator pump circuit (there is enough of a pressure differential) directly into the engine thru the vacuum hole in the bottom of the baseplate (where vacuum is present for the power valve). It is one of those problems where you can't see anything wrong and it'll run ok at highway speed but it'll idle stupid and the idle screws will be ineffective. If i were more computer literate i could provide you with the pics of each gasket, again, the wrong one has a half-moon cut out above the toumbstone-like opening for the powervalve chamber.

is this the carb you got from me ? .. it would not act rite on my 4.3 V6 either ..

ojh, I have a holley 9040 parts carb that does have the brass tube. It is unusable due to the main body actually being cracked (got it at a garage sale for $5... was worth it for the parts). but yes, I understand what your talking about, and I did indeed use the proper gasket. Still a fascinating idea, and just for fun, I'll take the carb apart in the morning and block the port manually just to see if that could be it

Yeah, hoss it's the one I got from you. Maybe a previous owner tried drilling something out or some such thing....
I've swapped base plates, blocked off the choke and secondary vacuum ports, etc.
I give up. I'm back to work in two days, I've got the cash to buy a new carb, so I'm going to. (Plus I really need this running so I can sell one of my other vehicles).

Either way, Thanks again Hoss... although not the intended purpose I received a fantastic schooling on Holley 4160 carbs on account of this.

Drew