jfb

bare with me I did not check for past info first of all. I enjoyed my olds this last summer and went everywhere I could with it. I had a problem though gasoline from bp,exxon,mobil,marathon,shell especialy and citgo seemed to perculate even with heat isolators under the carb and the fuel line insulated. I was wondering if there is a gas product out there to cut down on this problem. I also use a cool can . I had some lead in my tank that before hand cut down on this problem it was max lead 2000. I do though have a new gas tank the car is rebuilt. I had zero issues with this after the 3rd week of September and the car gets all tune up parts every year except the msd wires are replaced every 2 usually. the gas cap is vented and everything is location correct plus a high volume fuel pump. so is todays gasoline a issue guys it usually perculated when around july 10th-late august and caused some starting issues only and I do not have a choke either I have a double pumper holley. after Septembers noted week above it started fantastic with labor day gas still in the tank and no other changes.

Fun71

Was it hotter this summer than typical? Fuels are blended to tailor the vapor point for the ambient temperature. If the fuel's vapor point is low, as in a winter blend gasoline that is designed for use in very cold temperatures, and it is used during the summer with high temperatures, the fuel will evaporate/boil too fast. I'm not really sure that a slightly hotter than typical summer would cause that issue, though. I can see having a problem if you were to use Chicago winter blend fuel during 110+ summer temps in Phoenix.

oldcutlass

Seems taht you covered most of the fuel suppliers in your area. Doubt its the fuel.

jpc647

Mine does this too. It's the underhood temperatures combined with (everyone says) the ethanol.

Can you elaborate a bit on how you insulated the fuel lines? Maybe there's a better way. What is a cool can?

jfb

I covered the fuel lines with pipe insulation. a cool can is a way to chill fuel it is very old school but overtime it has been effective for a lot of people. I also have a insulator under the car and a splash shield under the intake and a vented gas cap but I do have a open plenum torker intake. I also stated that after I bought gas in late september the hard start went away and even beforehand had zero performance issues and just a very hard start. I have done research on this and the gas quality is usually the issue now does anybody know of a product that cures gasoline perculation and products of s...l do not do this.

jpc647

There used to be an additive we'd add to boats on the lake when we knew they'd be idling for a long time. Something blue. I'll see if I can't dig around and find the name.

The only other thing I've read people doing is using AV gas. But depending on your car that may be dangerous. Mines a stock, low comp, low hp motor, so AV gas would probably burn a hole through a piston.

allyolds68

I had an interesting thing happen this summer.

I always run 93 octane with ethanol because non-ethanol 93 isn't available in my area. I never have an issues with it. I took a trip down to Watkins Glen which is about an hour from me with not much in between. About a 1/4 of the way there I realized I was almost on Empty. The only gas station around had non-ethanol 91 octane as their highest grade of gas so I filled up. I had dieseling and pinging with that whole tank. As soon as I filled with 93 again I didn't have any problems.

Fun71

The big issue with Av Gas is its vapor pressure is formulated for very high altitude operation so the gas will evaporate properly. Using it at low altitude means the gas won't evaporate as easily as the carb/engine needs for proper operation.

jpc647

Right. But for some people who have issues with the current gas evaporating too quickly, some how found adding a few gallons per tank(albeit expensive) helps remedy the problem. It doesn't evaporate as quickly, which is exactly the problem with ethanol blended pump gas, it evaporates too quickly.

Fun71

A lot of folks say that, but I have not experienced it. You'd think that the 115+ summer temps here in Phoenix would be the worst case scenario for rapid evaporation but it isn't an issue here.

jpc647

I'm jealous. On 80 degree days here in Mass I can see fuel bubbling/boiling in my inline filter. I can only imagine what it's doing in the carb.

What's your setup. Mechanical or electric fuel pump? Hard line to the back of the Quadrajet? And insulation on the line?

Fun71

Factory replacement mechanical fuel pump, rubber hose (with inline filter) from pump to FRONT of QuadraJet, no insulation anywhere.

I suspect the real difference is that the gasoline here in Phoenix is formulated so its vapor pressure is correct for the high ambient temps. I didn't change anything in the fuel system when I moved from the Gulf Coast south of Houston to the Phoenix area.

jpc647

Send me up a 55 gallon drum of that good gas so I can try it out, okay?

Fun71

Well, I wouldn't really call it good. It's 10% ethanol, 91 octane max.

jfb

I am reluctant to use max lead again guys. I have 2 left over bottles from my c head days. I am currently running aluminum heads from edelbrock with a good high compression ratio. I also have a new tank lines pick up etc it is all new. I will periodically check back but I am hoping there is a product out there that will stop gasoline from evaporating. with no changes but to late September I had no problems and it was cooler and of course dew and humidity as normal. summer times issues have to be hashed out for next years gas otherwise and as I see we all could have some hard starts and possible stranded places to be at.

jfb

I noticed a comment from above guys so did you find that product yet?

wr1970

Why do you think leaded gas is a problem for your car. The only problem i see is cost. JMO

Railguy

I had this problem!!!! It's not boiling you hAve leak between the fuel pump and the tank. The bubbling is air being suck in. There were no clamps on my fuel line it worked fine for about 8 years then it slowly it got worse and worse and worse until it couldn't get enough fuel to keep the engine running. Took me a whole summer to figure it out.
Railguy

jpc647

Wow. Okay, this might be worth investigating here. I'll remove the clamps and make sure everything is tight. Thanks!

But let me ask, how come my car runs fine when it's cold. Unless the leak is only present when the rubber gets warm. Maybe I'll start with checking the lines near the motor. Especially the small one where it comes through the frame.

Not sure how I can test that entire line for leaks without changing everything, which is a big undertaking.

Railguy

Believe me I chased this thing all summer long. Replaced almost the whole fuel system. Which was new as it was. Dropped the fuel tank cleaned everything. It was like it was running out of gas.which it was. If I were you I'd start with adding a fuel pressure gauge.
Railguy

Railguy

No idea why It would run fine cold. I know when I took off from a light or stop sign it ran fine. Because as I approached a stop sign I had my foot off the throttle and bowl was filling up. But 75 or 80 on the pike it acted like it was running out of gas. Pull over and open the hood it ran fine . Back on pike same thing.
Where mine was leaking was the stainless lines .they were shipped in two pieces and put gether with a hose no clamps.
Railguy

Railguy

https://classicoldsmobile.com/forums...iling-gas.html
https://classicoldsmobile.com/forums...l-problem.html
Railguy

jpc647

I have almost the opposite problem, my car seems to run out of gas midway through first gear at WOT, hesitate for a second, at which point it'll shift into second, then it seems the gas comes flooding back, the motor catches it, and bang I'm off again. But then the car has to go back down into first.

Shifting manually, the car still acts the same way, without the transmission shifting.



Somehow installing a fuel pressure gauge and driving around for a couple of days and seeing what happens when it freaks out, is probably a good idea.

A vacuum gauge probably wouldn't hurt too.

Now, forgive me for a dumb question, but doesn't putting a T in the line to add a fuel pressure gauge give a sort of false reading of whats happening. Even if I had a long enough hose to zip tie it to a windshield wiper and drive around for a while without spewing gas everywhere, I might actually need 10-12 minutes of driving to get everything hot and to the point where I have problems.

IS there a better way to do this, without running a complete "permanent" install?

Fun71

I had those same symptoms back in the 80s, but it happened only when I got a lot of tire spin coming off the line, and it was due to the carb running out of fuel. I set the float a bit higher and it cured the problem.

jpc647

But my tires aren't spinning. :'( . The motor runs decent, but it's not a hot shot. I think it's just the shi**y new edelbrock carb. I did adjust the floats twice, they are a little lower than spec to allow a little extra fuel. I just don't understand a stock, low comp 350 that can't even one wheel peel running out of fuel.

I might send my original Q-Jet out to either Hobb's of the guy in CT to have them glass beaded, and fully rebuilt. Maybe have it jetted up a step or two for the dual exhaust, the 3.23 rear end, and the manifold.

Just don't want to waste $200+ to have the same issue.

Fun71

I don't think it would be a waste as you would have a nicely built QJet that in my opinion would enhance the value of your car.

jpc647

That's a valid point.

I guess I try to be frugal. But i've pretty much exhausted everything with Edelbrock. Maybe the Q-Jet won't fix my problems. But I should be able to sell the rebuilt carb for more than the rebuild cost, if it doesn't work for me.

Railguy

I thought of a good test. Remove the fuel line from the carburetor. Plug the line so fuel doesn't go every where. Then start the engine and run it until the carb is empty try to re start pumping the throttle to make it as empty as possible. Leave it set until your sure it's cold. Reattach the fuel line . Then Have Someone Start It Up While You Look For Bubbles or boiling.
Railguy

jpc647

I haven't been able to find it. I know it had "Blue" in the name. and it wasn't blue majic products. A lot of people mention trying a small amount of Diesel fuel per tank to eliminate it. Some mention Kerosene. I don't know about that. Seem like a bad idea. And unless they are constantly mixed I see them "separating"


That's a good idea. My only problem, is now that the outside air temp is 45-50*F I'm not seeing the bubbles. I've been measuring the temp on the carb the last couple days right before I shut it down, the carb is right around 145*F. I even put a small piece of electrical tape to get a matte finish for the IR light. The readings before, during high temp 80* days was 180-190(if I recall correctly)*. But I only measured one day, and we haven't had another warm warm day.


It's bizarre. Sitting in traffic for a couple of minutes, if I give it more than a little gas, there's a quick bog then it catches. but if i come to a stop light and immediately go again, the bog isn't there. I'm beginning to think the fuel pump, as most of the time the fuel filter is empty. But I really can't judge from that, I wish I had a clear carburetor and I could see if the bowls were "empty". But if I crank the motor the fuel pump spits plenty of fuel into the cup. But the fuel pump is at least 10 years old. Autozone sells one for $25. It might be worth swapping it just to see.

I'm sorry I hijacked this thread from the OP. :/

jpc647

I decided to bump this thread. I've been doing some searching into the raising the boiling point, and a lot of people are using Diesel fuel. A 1/2 quart to a tank to a quart for a tank. Some are using kerosene(this makes me nervous).

And Newly I've discovered people using IMCT. Which is Industrial Maintenance Coating Thinner. KleenStrip makes it. This sounds crazy, but it's true.

IMCT does burn hotter than gas, and i've seen people talk about mixing about 1oz per gallon. The higher the compression the less you start out with. This is one of those use a little bit and slowly work your way up things people are experimenting with. I don't think I would do this, but there are a lot of people with 50's-60's cars trying it.

I would probably try the Diesel fuel trick, and see if it helped just enough not to have to play with something else. I might start with 1/2 quart and go up to 1 quart.

On the other hand, how much trouble do we want to go through. They do make fuel injection systems than can be installed to prevent the need for all of this. More efficient, easier starting, no need for any maintenance. But yes, to answer the OP, you can, in fact, increase the boiling point of gas with additives.

Or there are plenty of LS motors out there to swap in, and never worry about any of this again.

jfb

I know this is really a late post but the season is almost here for usand thanks for thw replies. 1 I have no leaks in my system. 2 diesel fuel or additives like it are a option I will not consider they could clog things.3 fuel injection is costly also and the majority have carburetors to work with so that is the issue to be worked with. I am going to try stabil with every tank this year. I have learned overtime that lead used to stabilize the gas to a extent and the aromatics made it heavier and hence non evaporative to a extent and stabil seems to be a good additive for that missing ingredient. So does anybody have experience with changed gasoline this year yet I am open for suggestions and hi jacking this thread is ok as long as we all get answers.

jpc647

What makes you think diesel fuel will clog something? The problem with stabil, is while it does perhaps prevent evaporation, you will notice a performance change in the car running it.

jfb

I have never gone into the properties of diesel fuel or studied it first of all. I have heard that diesel fuel can clog fuel filters more easily though and maybe diesel fuel filters are designed for there use if someone has experience with diesel fuel in gasoline engines I am all ears and learning from someones experience. I normally due not run stabil all of the time but I do use it for lawn care machines and have not noticed a issue with them when running the treated gasoline.

olds 307 and 403

First off Dodge had boiling issues when they used AFB and AVS for factory carbs. No doubt one of the reasons the Thermoquad went to the phenolic bowl. Just unbolt the Edelbrock carb and throw it as far as you can and get that Qjet built. Gas has changed but my Dualjet and Qjet work fine with the Ethanol blends.

jpc647

If thats true, run a filter before the pump, to make sure the pump never clogs. And replace it every couple of months, or every 2000 miles. I haven't experimented with Diesel fuel yet, cause it's winter, but if it helped with fuel percolation and boiling, i'd happily change out a $3 fram filter regularly if it's getting clogged.

I guess what I'm saying is, it's worth trying. For a quart of diesel fuel, and a couple dollar fuel filter, it might be a solution.

jfb

I use a holley and have a phenolic plate under it as a heat shield and this plate was designed to stop heat soak.

jpc647

I found the phenolic spacer onlyou prolongs the inevitable. Maybe gives me an extra couple of minutes.

jfb

the time is quickly approaching guys for heat and humidity. I contacted 3 places who make quality products for our rides to blend with fuel. they said that todays gasoline is formulated for fuel injection and have several complaints from carbureted car owners and they have said that yes it is true about todays gasoline evaporating too quickly. so it is up to us to find a solution and av gas really is not a solution it will be almost impossible to get in to get it. anybody have a healthy solution for our olds out there like i said above it is happening to a lot of people that contacted them.

oldcutlass

People are running these old engines with carbs down here in Texas with summer temps ranging from 90-110+ degrees with no issues. I don't understand what your trying to do.

CRUZN 66

I haven't had any problems as yet here in the northeast... I do use additives from time to time...