Lean Run After Sitting?

[rebootej]

With the warm weather my engine as developed a lean run where it wont idle after I park it for between 30 min and today was 4 hours. Its starts but immediately leans out and wants to die unless I keep giving it some revs. Basically i have to drive it with two feet until I can get up to speed on a road for about a mile or so. At that point It runs fine.

I know its a heat issue, today when I was trying to fix it i felt the carb and it was so hot i could barely touch it, after i drove i the car I could easily put my hand on it. Is this a vapor lock situation? I have an aluminum spacer between the carb and spacer. Any ideas how I can fix this? My car doesn't run that hot, around 190 in warm weather.

Engine is a mildly built 318 with a 625 Speed Demon. I need help! Appreciate any ideas you guys might have!!

 

[mentor70]

this could be a hot soak issue.

todays fuels boil quick, and then it takes time for the new incoming fuel to cool off that hot carb. i see your in Cali too, our gas really sux

also ck the condition of ALL the rubber lines in your fuel system. replace any dry rotted looking hoses even if they are not leaking fuel, they can still suck air in.

 

[Yatzee]

With the warm weather my engine as developed a lean run where it wont idle after I park it for between 30 min and today was 4 hours. Its starts but immediately leans out and wants to die unless I keep giving it some revs. Basically i have to drive it with two feet until I can get up to speed on a road for about a mile or so. At that point It runs fine.

I know its a heat issue, today when I was trying to fix it i felt the carb and it was so hot i could barely touch it, after i drove i the car I could easily put my hand on it. Is this a vapor lock situation? I have an aluminum spacer between the carb and spacer. Any ideas how I can fix this? My car doesn't run that hot, around 190 in warm weather.

Engine is a mildly built 318 with a 625 Speed Demon. I need help! Appreciate any ideas you guys might have!!

It is best to use a phenolic spacer rather than aluminum as you still have heat transfer with the aluminum one - 1 inch is ideal. You'll probably have to dismantle, inspect and clean the carbuerator as your "air to fuel" mixture is off. Some bulky air cleaners pool the heat up under them so try running the car temporarily without the cleaner and see if there's a difference. You may also want to inspect your timing values because you may be set a bit retarded. But it sounds more like a fuel mixture issue if you have to use both feet to get it to run when put in gear.

 

[oldbee]

Stock exhaust?(stuck shut heat riser)

 

[rebootej]

So what can i do to cure the heat soak. Ill get a phenolic spacer and try that but its weird the car just started doing this. Last spring/summer it wasn't doing this. As to the air fuel mix its only lean when the car has been sitting after being run. Normally it is between 12.9-13.3. Ill double check all of my hose connections too. Is there any thing i can do to help prevent the carb from soaking up the heat?
Oh ya and I'm running headers, no heat riser.

 

[Fran Blacker]

Weak fuel pump? I'd try the phenolic spacer first.

 

[oldbee]

Go to summitracing and look at carb spacers. Delco had a real nifty spacer with aluminum in between the gaskets that extended out 2-3" fore&raft to cover the float bowls on Holley's. Used it myself years ago.

 

[rebootej]

I have wondered about this fuel pump... I had a glass filter on there for a while and it would often rarely get full.. But yes i will try the spacer first though.
Looked at summit didnt see the delco but found this Holley one that looks decent.
https://www.summitracing.com/parts/hly-108-70/overview/

 

[Lionized]

I have wondered about this fuel pump... I had a glass filter on there for a while and it would often rarely get full.. But yes i will try the spacer first though.
Looked at summit didnt see the delco but found this Holley one that looks decent.
https://www.summitracing.com/parts/hly-108-70/overview/
View attachment 417203

What fuel are you running?
Have you switched brands?
Does it contain Ethanol?

 

[Bruzilla]

I agree on the phenolic spacer, but be advised when you use one you're gonna be raising your carb higher, and you need to account for that with the throttle cable and kickdown. I have an Edelbrock Performer, 1" aluminum spacer, and a 1/2" phenolic spacer, and I had to cut the legs off my throttle bracket and weld them back on with a 2" spacer to make everything work again.

 

[rebootej]

Running premium fuel octane 93. It does have ethanol in it I'm pretty sure. I usually put Chevron in it or Shell. Hate the ethanol, the stuff is garbage.
Thanks bruzilla Ive got an aftermarket plate that mounts on the carb bolts, hopefully Ill only have to readjust it.

 

[RJRENTON]

Gentlemen,
Re the fuel issue...
Alcohol blended fuels are horrible. The alcohol component is usually ethanol but can contain a small methanol component. The two alcohols are similar but have slightly different boiling points. The amount of alcohol being blended can vary depending on the refiner but in all regards, because alcohol has, roughly, HALF THE ENERGY VALUE of gasoline, in order to get the same energy from it, twice as much must be burned. Just look at the Holley jet selection guide, the metering orifice is considerably larger for the same equilivant fuel flow.
The "hot soak" issue or fuel percolation (actually boiling in the carbs metering passages) due to the alcohol content cases a lean mixture...hard starting, stumble etc. until cooler fuel is introduced.
Generally, E85 Flex Fuel cars, get lower fuel milage unless operated on pure gasoline. The engine management computer measures the fuel density and adjusts the engine's fuel injector's on time (increases the pulse width on time..hence more fuel is added) resulting in higher fuel consumption.
Is alcohol blended fuels beneficial??? Personally, i think not, but politicians and corn farmers think so....because its a renewable sorce. If alcohol based fuels are better(?), why don't they cost less, based on their energy value, or at least based on the percentage of alcohol content? Food for thought.....
Bob Renton

 

[rebootej]

I agree completely. Corn is a horrible crop for ethanol production it takes a lot of energy, land and only corn portion is useable, none of the stock is useable and it takes subsidies. Sugar cane would be better.. I you really cared about renewable energy.

Ok rant over. What psi should my fuel pump be putting out? I like to check its performance. Its only regular pump from Napa. The first one I got from them was bad out of the box..

 

[rebootej]

Checking back in.. about 80% of my problem was timing. The engine was way to retarded at 8 degrees BTDC. Advanced the timing and its running way better. Current at 15 BTDC seamed like way too much but the engine is happy... so i guess its okay?