Alcohol in gas affects mixture

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jrm81bu

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Jul 9, 2008
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Oh now were only talking bone stock stuff huh? Wow, guessed you missed the part where Bonnewagons carb isn't stock spec. You said ANY engine would run worse with ethanol and no other changes, now mine doesn't count huh. Aren't you one of the guys that says in order to run aluminum heads you have to have more compression or it'll make less power too? If it make you feel any better i'll take the belt of and run it. You can't make any assumptions about how optimized my engine is for anything. You are stating that an engine set up to run 100% gas will run like sh*t with E10. Mine has always been set up for 100% gas until I just decided to throw in 30-40% ethanol not just 10% and it's just fine, boost or no boost.
Now just because Boonewagon's engine picked up with a jet change still doesn't mean it was because of ethanol. Who's to say the place he is getting gas isn't using junk gas. Or that jetting it up didn't just mask another problem he hasn't discovered yet.

I still haven't seen how you can justify counting the ethanol out of the a/f ratio in your example, just to make it "look" leaner.
 

CWPottenger

G-Body Guru
Oct 9, 2012
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Ethanol is by no means new. Mfg have made engines and fuel systems to handle up to E10 since the mid to late 70's when it was re-introduced to main stream public use.

To go back to the OP statement upping his jets solving his problem is not as definitive as to Ethanol related or non related. Carbs have multiple fuel and air paths that work together to give engine what it needs at different throttle/ load response. Sometimes just taking a carb apart and reassembly "fixes" an issue. Other times two supposedly identical carbs run differently on same motor. There is no std carb setup that works all the time on each motor. On a separate note on the OP statements I am confused by his post that his fuel bowls were empty after a few days. I haven't mentioned it because I'm not a Qjet person, I know on everything I own the fuel is still in the bowls weeks after I have parked them from lawn mowers to cars, so to me that points to some kind of an internal leak.

This like every other Ethanol post on every forum is an apples to oranges, results to beliefs argument that has no winners.

Those that take the time to research their own cars parts and tunes according to results not belief will be rewarded with a vehicle that performs as they need or want.
 

Bonnewagon

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" I am confused by his post that his fuel bowls were empty after a few days." CW, remember all the posts the last several years about "why is my car so hard to start"? It has been proposed that the alcohol causes the gas to evaporate faster, thus after a few days, you must crank and crank to fill the bowl and start. I too have seen this but never could prove it. That is until I put the car in my back yard, and the next day yanked the carb being very careful not to spill the gas. Upon removing the air horn, the gas from only one day ago was gone. Do not fall for the "all Q-jets leak" myth, that was cured by Rochester Products in 1970. You do not need to epoxy the bowl casting plugs like we did on the 60's carbs. And yes, prior to E-10, a carb would take a long time to evaporate dry with just gas, and then it would deteriorate to that smelly slimy greenish stale gas crud we all remember. All it should take was one pedal press to set the choke and give a quick squirt from the accelerator pump and she started right up. Now after a couple of days, the bowl is dry. In my case, it was a hot motor parked in the sun, and in one day it was dry. Also I am pretty diligent about my carbs and after several rebuilds, it still pinged. I stated that I don't think I "fixed" anything by accident and I stand by that. I can only add that on the 301 Garage Forum Joe stated that after speaking with Cliff Ruggles and others the factory jetted these carbs for tighter emissions and only emissions, and that a stock 301 needs a lot more fuel than it was given. OK, but #73 jets and #44 rods ?!? In the old days a 400 would gag on that set up. Not just trying to stir the pot here, but I still think the E-10 is the culprit.
 

CWPottenger

G-Body Guru
Oct 9, 2012
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Bonnewagon said:
" I am confused by his post that his fuel bowls were empty after a few days." CW, remember all the posts the last several years about "why is my car so hard to start"? It has been proposed that the alcohol causes the gas to evaporate faster, thus after a few days, you must crank and crank to fill the bowl and start. I too have seen this but never could prove it. That is until I put the car in my back yard, and the next day yanked the carb being very careful not to spill the gas. Upon removing the air horn, the gas from only one day ago was gone. Do not fall for the "all Q-jets leak" myth, that was cured by Rochester Products in 1970. You do not need to epoxy the bowl casting plugs like we did on the 60's carbs. And yes, prior to E-10, a carb would take a long time to evaporate dry with just gas, and then it would deteriorate to that smelly slimy greenish stale gas crud we all remember. All it should take was one pedal press to set the choke and give a quick squirt from the accelerator pump and she started right up. Now after a couple of days, the bowl is dry. In my case, it was a hot motor parked in the sun, and in one day it was dry. Also I am pretty diligent about my carbs and after several rebuilds, it still pinged. I stated that I don't think I "fixed" anything by accident and I stand by that. I can only add that on the 301 Garage Forum Joe stated that after speaking with Cliff Ruggles and others the factory jetted these carbs for tighter emissions and only emissions, and that a stock 301 needs a lot more fuel than it was given. OK, but #73 jets and #44 rods ?!? In the old days a 400 would gag on that set up. Not just trying to stir the pot here, but I still think the E-10 is the culprit.


Was not in any way saying you were wrong or not good at Qjets. I have thrown every Qjet I ever got on a car or car I worked on in the trash can. I am a Holley person, which is why I wasn't sure how Qjets bowls size or design work that might accelerate evaporation with ethanol. Not an issue I have ever had with a Holley and Ethanol blends. Typically a factory tune no matter the year or make in the last 30 yrs is the worst for power and efficiency and tuned for emissions 1st and foremost.

My only point is that Ethanol is not the evil it is portrayed as and no matter the engine combo/fuel combo real world results, tuning and testing are the only Facts that matter. Others can quote all the charts, math, etc., but results rule the day.

I'm happy your jet change made your car more reliable and fun to drive. The more time we spend driving vs wrenching is a great day.
 

Bonnewagon

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Understood CW, I was just explaining what happened to me. I'm not vilifying the alcohol, just trying to understand what changes it causes. I think the scientific statements made by Clone TIE Pilot and gp02a0083 pretty much explain and back up my own real world findings. And since every single car I've ever cared about came equipped with a Rochester carb I made it my business to learn how they tick, be it Q-jet or single barrel. Anyone who speaks Holly is way ahead of me, as I am all thumbs with them. :blam: Another thing I noticed was that in winter, the fuel bowl evaporation was not so bad, which would make sense. Now imagine a 90º day and the poor carb is sitting on top of a red-hot intake manifold exhaust crossover. The fuel has actually been observed boiling in the bowl, and the factory has addressed this with things like thicker carb base gaskets and electric EFE systems. But now there is alcohol in the mix, so after a few days I just expect to crank away for a while. Oh, one other thing. This same '80 TA carb that, besides being previously installed on a stock '80 TA 301, was used on a turbo 301 motor that was converted to 4 barrel and ran flawlessly. Thus I *ss-umed it would be a natural on my current vin "W" 301 motor. When it pinged I again *ss-umed it must be something else and I wasted much time on things like ignition advance which helped not at all. I forgot that a turbo 301 has even less compression than a regular 301, so no chance of pinging. So maybe I am deluding myself about the alcohol, but I sure am happy I changed those jets! 8)
 

gp02a0083

Master Mechanic
May 17, 2011
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Bonnewagon, the worst the ethanol does on our older cars is rot the rubber lines and a few other parts. these are things we all kinda know to an extent. All i know about the Qjets and rochester cars in general is that they are really finicky and it doesn't take much to set them out of tune. Just curious with your situation, did you check the fuel line pressure by any chance?
 

Bonnewagon

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No, I have not checked the pressure. It is however a recently replaced pump, with the correct return line to the tank. For a time I was using this brand new return type pump with no return line, I had just plugged the port on the pump. What this does is overpower the float because the return line volume has to go somewhere and that causes an insidious flooding problem at idle and low speed. At normal driving speed you will never know except that the spark plugs prematurely foul. I temporarily cured this by plumbing the fuel return port to the incoming fuel supply line so it had somewhere to go. Problem solved and I was motivated to instal the correct fuel tank return line on the car. With this new pump I can run at WOT as long as I want with no fuel starvation, but before re-jetting, I got some pinging . Now it really roars. PS- thank's for the Chemistry lesson!
 
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