wit's end

[ndutton]

I think this is really about the practicality of the concern or in other words, is it really an historical problem?

Example: my A-4 was salt water cooled for at least 35 years, never winterized, likely never acid flushed, never had any zinc protection, had the dreaded yellow brass machined elbows in both manifold ports, inlet and outlet.

No problems, no indication there had ever been a problem upon easy disassembly. Sorry but it's undeniable and can't be ignored.

[hanleyclifford]

I think this is really about the practicality of the concern or in other words, is it really an historical problem?

Example: my A-4 was salt water cooled for at least 35 years, never winterized, likely never acid flushed, never had any zinc protection, had the dreaded yellow brass machined elbows in both manifold ports, inlet and outlet.

No problems, no indication there had ever been a problem upon easy disassembly. Sorry but it's undeniable and can't be ignored.

The stock brass elbows furnished in the A4 are not close, but much more robust pipe to barb fittings.

[hanleyclifford]

Getting Serious About Flow

If you really want to jack up the flow, and get more robust and have better, safer choice of fittings try opening the manifold to 3/4" NPT, easy and plenty of "meat" to work with:

[biohead]

lighting gas in parking lot = boom

Don't try to light the gas in the parking lot...gas goes boom...even the small amount in the bowl.

First thought is 'Are you getting gas?'
I'd drain what's in the carb, dump it in the parking lot, and see if it burns. Sounds like you may have a load of non-gas in your fuel tank.
Quick check is to connect a small tank of known good gas to your engine and see if you can get it running. If it runs, attack your fuel supply issue. If it doesn't, back to the carb.

[damienk]

I have to say I am blown away by the amount of knowledge on this forum. Blown away. you all got it right, and you all have very pertinent remarks. And sorry for being quiet for a couple days I was away from civilization
So yes, the hoses are a mismatch and I understand that the fittings aren't the best but I will hold on those projects until I get my A-bomb running loud and clear.

So right now:

Gauge:
The sending unit is brand new, so I guess it works. I will remove the teflon tape as suggested, and if it works better, I will keep it that way. If it doesn't, I will buy a gauge. Using a ohm meter is way too scary haha.

Overheating:
I did the test with a clamp in the bypass and no overheating. I removed the clamp, no overheating (all checked with heat gun). Thank you all for giving me the range of temperature that I should expect. Apparently, I am now fine with that. I guess that the acid flush, the cleaning of the water plate and the manicure of the head and manifold when I removed them or a combination of all the above somehow worked. yay!

Smoke:
I still have the issue of white smoke coming from the connection between the hot pipe/riser and the manifold. It is hard to tell if it smells like exhaust because I never really put my nose in the exhaust, but it definitely doesn't smell good (a mix of fumes and burnt smell, maybe burnt plastic?). That does bother me a lot, but hey, it runs. But Dave Neptune gave me hope that it might just go away (the riser did get wet inside, so hopefully, it is only boiling off). If not, I will be in the market for a new riser, unless someone else has a better idea?

And... the new problem (if you still have some juice for me lol):
Carburetor issue! I got the engine started using an old carburetor, that is close to being magic: anytime I use this old carburetor, the engine starts right up and purrs as smooth as an happy kitty, BUT I basically completely lose throttle ( I can rev up in neutral, but not in gear. NOT AT ALL). I troubleshooted this issue a long time ago and I know it is the carb fault, because I replaced the carb with another one and it worked perfect, which is why this carb is now my "troubleshooting" old carburetor. However, with the new one, it is not starting AT ALL.
So, I am here at home with 2 carburetors, trying to make a winner out of these 2 losers. I tried combinations of both, and got a rough start with the upper part of the new one (B) and the lower part of the old one (A). Couldn't try the contrary as the screw don't match (they are the same carbs inside, but slightly different outside).
So, anybody knows what to look inside the carb for to solve this throttle problem? I think that with the new one, it is the main jet that is clogged. But with the old one, I don't understand this issue. How is this even possible? I have them both soaking in vinegar right now and hopefully I can get them both to work well. I really don't want to fork $500 for a new carburetor, I already spent a ton of money on this engine lately.

Thanks to all for being so knowledgeable and supporting!

[hanleyclifford]

Looking at your engine where the hot section connects to the manifold I think I see something that looks like aluminum foil. Is that correct?

[hanleyclifford]

If you are having trouble with clogging in your new carb, possibly you suggest, the main jet, we should ask if you have a good filter/separator and a final "polishing" filter for the fuel. The best way to clean a main jet, or for that matter all the carb body passages and jets, is with ether or carb cleaner aerosol with the thin tube attached. The main jet should be removed and held up to light to see if it is plugged. I have jewelers drill bits to clean them but any fine wire will do. The job is best finished with compressed air. Be careful not to lose the main jet washer and reinstall just over hand tight.

[damienk]

Looking at your engine where the hot section connects to the manifold I think I see something that looks like aluminum foil. Is that correct?

YES. It is correct. Actually the whole hot section looks like aluminum foil. I think it is some kind of thermoformed heat wrap.

Cleaning the carb: Thanks for the ether advice. I'll try that and also use my air compressor. Can a carb just "go wrong"?
The carb A (turns on in a heart beat, steady and nice sound, but no throttle when in gear) has a very clean main jet and is actually pretty clean everywhere. Anybody has any idea what can cause that/ what to check?

[Dave Neptune]

d, look to the seal on the discharge tube and be sure it is clean. That is the brass tube that protrudes into the venturi.

Another check is to look at the old gasket closely. Where you want to look is in the area over the center of the bowl. This is the emulsion well and the top is sealed by the GASKET so look and confirm that you have good contact all the way around IE a bit of indentation.

Either of the above can really raise havoc by leaning where there is more demand, thus the lack of performance.

Dave Neptune

[hanleyclifford]

Looking at your engine where the hot section connects to the manifold I think I see something that looks like aluminum foil. Is that correct?

YES. It is correct. Actually the whole hot section looks like aluminum foil. I think it is some kind of thermoformed heat wrap.

Cleaning the carb: Thanks for the ether advice. I'll try that and also use my air compressor. Can a carb just "go wrong"?
The carb A (turns on in a heart beat, steady and nice sound, but no throttle when in gear) has a very clean main jet and is actually pretty clean everywhere. Anybody has any idea what can cause that/ what to check?

"Thermoformed heat wrap"? I am not familiar with that product. Could it be the source of the smoke?

[JOHN COOKSON]

I
So, anybody knows what to look inside the carb for to solve this throttle problem? I think that with the new one, it is the main jet that is clogged. But with the old one, I don't understand this issue. How is this even possible? I have them both soaking in vinegar right now and hopefully
Thanks to all for being so knowledgeable and supporting!

When you twist the main jet to remove or install it it's easy to damage the threads in the soft aluminum with the screw driver. The next time you try to twist the main jet in you think it is seated but it is not really seated because all you've done is tightened the jet against the damaged threads.

TRUE GRIT

BTW: Do you have an exploded parts diagram for the carburetor?

[hanleyclifford]

When you twist the main jet to remove or install it it's easy to damage the threads in the soft aluminum with the screw driver. The next time you try to twist the main jet in you think it is seated but it is not really seated because all you've done is tightened the jet against the damaged threads.

TRUE GRIT

BTW: Do you have an exploded parts diagram for the carburetor?

For this purpose I have dedicated screwdrivers from which the shank taper has been straightened on a bench grinder.

[damienk]

BTW: Do you have an exploded parts diagram for the carburetor?

No I don't, but I've been quite careful. All the parts go in and out smoothly, it doesn't feel like I damaged the thread.

d, look to the seal on the discharge tube and be sure it is clean. That is the brass tube that protrudes into the venturi.

If you are talking about the very small diameter flexible brass tube going from the bottom of the carb to the manifold, yes the are clean (and I just cleaned them again with carb cleaner+air compressor.

"Thermoformed heat wrap"? I am not familiar with that product. Could it be the source of the smoke?

Well neither am I (familiar with this product). I am just describing it to the best of my abilities, which isn't much. It looks like aluminum foil and it looks kind of "loose" or at least "flexible" but it isn't: it is as hard as rock. Which is why I supposed it was installed when it was flexible and then it became hard and matched the shape of the pipe/fittings under (so, possibly thermoformed?). But I know nothing. Just describing what I see and touched (and what you can see in the pics I uploaded).

I just finished rebuilding both carbs. The "new" one had a part quite clogged (the long skinny needle-looking brass part that is inside the carb, and has a a few holes in it). I hope this was the reason why it wasn't starting at all with this carb.
The "old" carb looked in perfect shape. So why is this one starting but not giving me throttle when in gear, that is a complete mystery.

On my way to the boat right now, will try both, and see if I still have the smoke from the exhaust.

[Dave Neptune]

d, no you are describing the "scavenge tube". The "discharge tube" is threaded into the throat and feeds from the "emulsion well". It is the "tube" that the 'air/fuel" is discharged into the "venturi (the round piece in the throat)" for proper mixing for the intake.

Jerry or someone have an exploded carb pic to post?

Dave Neptune

[damienk]

Dave I am still confused about the discharge tube. If you have a pic of the tube that would help. I took this carb apart a million times so I know the look of the parts even if I don't know their name or function.

I just tried both carbs after cleaning. It started in both. With both, I have good throttle at idle and in reverse. NO throttle AT ALL (cannot go past 1000rpm) in forward. whenever I am in forward, it is like the throttle shift is simply not there.

Of course, very strange that it happens with both carburetors, but I had the exact same problem years ago (with the carburetor I have now) and fixed it by switching to another carb (that I gave to someone in need, I now deeply regret it). So experience tells me it is the carb, but what in the world can cause that? I am almost ready to buy a new carb, but if it doesn't fix the issue I will probably cry.

Also, no smoke so far. I will try the engine on a little longer to check smoke and temp.