Well for the last few days I've been tooling around in my recently built, "Frankenstein truck". 66 Chevy cab and clip, 63 GMC 2500 series chassis with 305e and stromberg ww carb, 55,59 9ft stepside bed. When pulling out from a stop or heavier acceleration, I get a raw gas smell. It still has the tank in the cab but is brand new along with the sender and cap. All new lines and hoses and clamps all the way to the pump. No damp spots or anything like that either. I am also running the factory air/oil cleaner. Today I decided to take the air cleaner off look down in. Well the first thing I noticed after the strong gas smell was where the accelerator pump squirts fuel, it was sorta spitting about every other second for a few. Engine was off. Not sure if this is relevant or not. Performance wise, no black smoke, no hesitation, no other indication of a carb problem except for the excessive fuel smell when pulling out or on heavy throttle. Do I need to pull the carb apart or is there an adjustment for this issue? Ive never run into this b4. All input is appreciated. And Thanks in advance....
Wondering if it was percolating from intake manifold heat. Do you have a phenolic spacer between the carb and intake manifold ? Also, wondering if your heat riser is stuck and you are pushing hot exhaust through the manifold crossover? Steve
Last edited by sstock; 12/29/20191:37 AM.
1953 Chevrolet 3100 261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done In the DITY Gallery Video of the 261 running
1964 GMC 1000 305 Big Block V6, sm420, the next cab off restoration
Squirts with motor off? Are you pressing on gas pedal? Do you mean out the top where piston shaft comes thru? Do you actually see gas coming out or just wet up there from when motor was running and pump shaft was operating. Need better description.
The pressure has to be coming from somewhere. Leave gas cap off and try it for a while. If you get a pressure release sound or hiss when removing gas cap, that's a clue.
Do you have a electric fuel pump?
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
More like mini spits, bubbles. Not touching pedal. Coming from the top, inside of carb where it would as if you throttle it. No hiss at cap or appear to have tank pressure of any sort. No electric fuel pump. My concern is not when engine is not running, just mentioned it because that's what I noticed when I looked down carb. My concern is when engine is running, pulling out from start or heavier acceleration. Fuel smell is like I spilled it on myself.
Try lowering the float level a little. Chances are that the fuel is spilling over into the air stream out of the float chamber into the vent tube when the truck accelerates. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
I see what you mean now. OK, if carb is not leaking out onto motor, that's good. As you know fuel will squirt down throat. So your complaint is smell not spill/leak?...and no mention of performance loss. No hesitation, no bog, no backfire????????????????
I will let the gurus take over.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
Exactly. Just the smell. No spill, leak. No hesitation, bog, backfire what so ever......... I'm going to get a carb kit to have on hand and open it up. I will triple check the float level and lower it as suggested by Hotrod Lincoln. I'll let you all know the findings..
Those WWs have a sideways float setup, I am suspicious of them too. Mine on my 64 GMC smells so looks like Im going to Mikes Carbs and getting a kit.
1953 Chevrolet 3100 261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done In the DITY Gallery Video of the 261 running
1964 GMC 1000 305 Big Block V6, sm420, the next cab off restoration
Ok people.. Heres what I got. I actually pulled da carb off, pulled it apart and thought To myself let's adjust something..lol. So i googlled Stromberg WW float level, and found that Studabakers actually run da same carb, along with various Buicks bla bla bla.... Anywho the actual spec of 3/16 is to high because of modern day fuel. The spec should be 7/32nds measured at the center of the float. This is because of, that modern fuel has a buoyancy different than older leaded fuel and therefore the float rises at a different rate than it should be. Making more fuel requires to bring the float up to close the needle and seat than what would be required in older fuel days. I actually set my float at 6/32nds, alitta light, to see obvious change. It's a thing really to get it set to precision spec, so I thought atad lower might be better. I didn't drive it yet, but it snapped over like the carb was never off it. I let it warm up up, gassed it up multiple times, no smell. But an test drive will make it known if I'm barking up the right tree. Raining like cats and dogs all day, hence the lack of an honest road test. Found the info on studebaker-info.org.... I'll touch base again after the road test..
Sidenote.. I love the smell of fuel all the time except when I think I'm going to catch fire... lol
As long as you don't get the level in the float chamber so low that it tries to empty itself on a long uphill pull with wide open throttle, you can get by with a slightly lower than specified float setting. Also be aware that more venturi vacuum is needed to draw the fuel from the float bowl into the airstream, so a lower float setting will also result in a slightly leaner high speed mixture. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Noted and appreciated. Frankly I don't really have a choice but trial and error. And the research I find is hit and miss. Therefore relying on your guys opinions which is held to da highest standards.
I guess a litta bit leaner high speed mixture is a possibility rather than raw fuel fumes at low pull out. I'll pay attention to destination at cruise to boot. I'm hoping for da happy medium, I guess.....
In that case all other opinion would be wrong also, referring to the bounioncy aspects. Or is the listed specs for the carb a bit to high in the begin with?
Needle and seat seemed to be somewhat soft and clean on the needle side, and with no wear mark to the naked eye on seat side. Not that there wasn't wear. It just wasn't apparent if there was.
To be perfectly clear. I'm not one to doctor up the issue. If there is or was a known problem, I'm going to try to resolve it to the best of my ability. That's why I brought this issue up for discussion in the begin with. I don't want a bandaid. I want to repair the actual problem.
Have you ever wondered why the float level isn't the same for similar carburetors used for different engine applications? For instance, the same large-bore Rochester 2 barrel casting is used for 305 and 350 Chevy V8's, but the float level for the 305 is set WAY higher. The difference is the velocity of the air through the carburetor venturis. The 305 draws less air through the carb for any specific RPM, resulting in less vacuum at the venturi stack. There are differences in the jet sizes and power valve settings, but if the 350 float setting is mistakenly used on a 305, the engine won't get out of its own way because it's running so lean. Set the float right, and the lean surge, power loss, and backfiring goes away. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
I understand all of that Hotrod Lincoln. But as stated, I don't have ANY other issue than fuel smell when indicated previously. No backfire, sarge, power loss. Nothing.....
Gas leak wise would have to be fumes only. The complete system is brand new from the cap to the pump. I doubled checked all clamps, hoses. And steel line from rear of cab to front of engine was used. Dry. All dry. I wish I found a leak. Then I could fix it and be done...
Try the simple fixes first- - - -lower the float level a little and do a test drive. Also look for imperfections in the carb casting that might allow gas to escape between the main casting and the top from splash. It only takes a few drops of spillage onto the manifold to create a strong odor, and by the time you get the hood open and look for wet spots there might not be any to see. Also, look for clean spots around the fuel pump area- - - -I've seen gas squirting from a leaky pump casting, even on brand new pumps, but only at speeds above idle. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Update. I didn't get to road test this monster yet but took a much harder look at it. After carb adjustment, seems to start way faster at least cold. Not sure hot yet? Anyhow something caught my eye when i waved a trouble light in the right angle over the fuel pump. Look at pic closely. There is a very little spot of corrosion at the seam or crimp of the body, that appeared to have shiny reflection to it under light. I hit it with brake cleaner, compressed air, then waited. After a long minute or 2, I can see it appear again. I ordered a fuel pump for it but won't have it till Friday. I think another mystery may be solved, but will confirm after pump replacement.. Thanks to all for your time and expertise..
the bottom housing of the fuel pump has a tiny hole that drains the bottom side of the diaphragm to the ground this tiny hole often will plug with gunk then any leak in the diaphragm leaks internal to the engine and adds to your oil level instead of leaking external under the pump
I got the email saying bartamos replied to this thread, but don't see it in the thread???. Any how ill take that as a compliment. I've been called way worse than a bloodhound. Thanks. Lol. The very little leak as I seen was with the not running. I have no idea what's it doing under a load. But if that ain't my mysterious fuel smell, I bet sooner or later it will be.. Happy New Year
I decided that it may be taken the wrong way when I said "small leak, if you can smell that you are related to a blood hound". But I still don't want to say it............oops! Happy New Year G.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
FIXED.. After removing the fuelpump, i could see the weep holes. Looked stained. Installed new one. Drove it. And really didnt like hesitation i think i created. Returned to garage pulled carb back off and set the float level back to 3/16. Drove again, got gas at near by station to top off tank. Run much better, No gas smell either, which was the issue in the begin with. Needs driven again but happy with results so far. Thanks to all for the input.
Good on ya- - - - -and thanks for the feedback. Sometimes when a problem gets solved, nobody bothers to let us know what fixed it! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
