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Whenever this old fuel bowl evaporation thing comes up I repeat my experience with dozens of carbs I've rebuilt....
I install them bone dry and the cars start within 5-7 seconds of cranking and pumping the gas....some might take a tad longer but very rarely...
That's AFBs, WCFBs and Q-jets...
I have many friends who report the same experience. Its the variability between cars and carbs that get me. My AFB's are the best running but most difficult starting if idle for 2 or more weeks. My 4GC will start, no choke, as if it had no idea of ambient temperature.
Since initial light off has little to do with the choke what do you say accounts for all of the various experiences everyone has?
My temps aren’t as high as yours but after weeks up on the lift mine fires off with no choke after a pump and a ten-count at most. It’s easily the most reliable starting old car I’ve ever had
I have many friends who report the same experience. Its the variability between cars and carbs that get me. My AFB's are the best running but most difficult starting if idle for 2 or more weeks. My 4GC will start, no choke, as if it had no idea of ambient temperature.
Since initial light off has little to do with the choke what do you say accounts for all of the various experiences everyone has?
Dan
I can't really say. More than likely a combination of things...
I had several experiences of vapor lock two summers ago.....I installed the same model carb which I had freshly rebuilt last November and no more vapor lock no matter how I treat the car... Strange.
I have many friends who report the same experience. Its the variability between cars and carbs that get me. My AFB's are the best running but most difficult starting if idle for 2 or more weeks. My 4GC will start, no choke, as if it had no idea of ambient temperature.
Since initial light off has little to do with the choke what do you say accounts for all of the various experiences everyone has?
Dan
I haven't looked closely at the top on an AFB in awhile but I noticed a couple years ago when rebuilding an 800 Edelbock (AVS) that the fuel bowl vent on them is really large and opens directly into the bowl. I suspect that just encourages evaporation/escape of the fuel volatiles. By comparison a Holley bowl vent is quite a bit less direct - but then a lot of them have the little vent on top of the primary fuel bowl too.
Last edited by DansYellow66; 09-17-2018 at 07:19 AM.
I don't run a choke on mine, plate is removed. If it has been less than a week, I don't pump the gas, it fires as soon as the first piston rolls over TDC. If it has been over a week, three pumps, and same.
I don't run a choke on mine, plate is removed. If it has been less than a week, I don't pump the gas, it fires as soon as the first piston rolls over TDC. If it has been over a week, three pumps, and same.
There are some (many?) that don't know how to 'baby' a cold engine for the first few moments of operation to get the thing moving without it dying....it takes 'feathering' the gas and avoiding 'hole shots' from a stop for a few minutes...
There are some (many?) that don't know how to 'baby' a cold engine for the first few moments of operation to get the thing moving without it dying....it takes 'feathering' the gas and avoiding 'hole shots' from a stop for a few minutes...
I beat that problem. I installed a solonoid, attached to the windshield wiper box, that pulls the throttle linkage. I have a switch under the dash to activate it. This bumps the RPM and holds it there without the need to feather the throttle and is especially nice at the closest stoplight where the car is still cold and could/would die unless feathered. Hit the switch just before reaching the light and voila, no stalling! Turn it off after leaving the light and I'm good for the duration.
Also, it alleviates the need to "3-pedal" at the stop signs on the hills to reach the first light. My "line lock" also helps here for the stop sign at the top of the hill.
There are some (many?) that don't know how to 'baby' a cold engine for the first few moments of operation to get the thing moving without it dying....it takes 'feathering' the gas and avoiding 'hole shots' from a stop for a few minutes...
Oh yeah, I have had some really cold-blooded cars in my time. But my 63 isn't one of them. It fires immediately and settles into a smooth idle. If it is really cold out, I'll have to lightly blip the throttle to prevent it from loading up. I'm running a stock ignition system with a Holley 650 double pump on a performer intake.I picked up a C3B-X intake at a swap meet last year, but haven't had time to install yet.
Oh yeah, I have had some really cold-blooded cars in my time. But my 63 isn't one of them. It fires immediately and settles into a smooth idle. If it is really cold out, I'll have to lightly blip the throttle to prevent it from loading up. I'm running a stock ignition system with a Holley 650 double pump on a performer intake.I picked up a C3B-X intake at a swap meet last year, but haven't had time to install yet.
Here is how I added a "fast idle" to my milled Holley. Note that while it doesn't really show, the ignition shield is in place and hides all of this.
Solonoid is mounted to the side of the windshield wiper motor assembly. I cut down the spring to reduce the tension and there is a thermal switch sandwiched between two resistors to prevent overheating if I forget to shut it off.
Lamp chain is used as the interconnecting link. The ***** allow for a quick, easy "pert near."
A couple nuts/screw adjustment takes care of the "fine tuning."
The chain connects to the linkage at the joint.
And a switch under the dash allows me to manually toggle it (along with my line lock and rear vent). The red **** behind the parking brake is a Tilton 7-position, brake proportioning valve for the rear drums.
There are some (many?) that don't know how to 'baby' a cold engine for the first few moments of operation to get the thing moving without it dying....it takes 'feathering' the gas and avoiding 'hole shots' from a stop for a few minutes...
The AED prepped 750DP Holley with no choke horn on my 355 takes two pumps. 5-seconds, and it's an almost instant start, even if it sits for a month or more. It does not have fast idle cams. I have to coach my son to hold it at a +1200rpm fast idle for a minute to assure cam lobe oiling after sitting and heat the pistons and heads. Even without carb heat passages in the heads it will settle down to a 750rpm idle after 60 seconds of warm up.
One caution with vented tank stored oxygenated fuel is water absorption in the ethanol along with condensation, and water separation and settling in the bottom of the tank. The fuel pump delivers mixed water from the bottom of the tank, rather than quality fuel. You can pump watered down fuel into the carb & intake for a long time without engine fire. Static engine operation without road motion to mix the ethanol just adds to the water separation problem. Aircraft have tank drains to clear the water in the wing tanks, part of the pre-flight checklist. Operating the engine closer to empty than what is advised with modern FI will help to burn through the poor fuel.
Actually, if my 67 has sat for a couple weeks or more, I do NOT want it to fire up immediately on first crank. Instead I will let it crank with no throttle shots in a couple of 5 second bursts until the oil pressure comes up tp 30 psi or so.
THEN a couple pumps on the gas pedal and it fires right up! No choke on this one / just hold 1500 rpm or so for about 30 seconds-and good to go cold.
There are some (many?) that don't know how to 'baby' a cold engine for the first few moments of operation to get the thing moving without it dying....it takes 'feathering' the gas and avoiding 'hole shots' from a stop for a few minutes...
Indeed. From the factory this setup had exhaust heated carb bottoms but not with headers. No choke. This car responds favorably to a prescribed sequence of events similar to you fellas, but it has to be what it has to be to get a reasonably quick light-off. 30 seconds of foreplay (feathering) and yer off.
Why would you be doing "hole shots" with a cold engine anyway?
Seems like that might be hard on equipment whether you had a choke and/or heated intake?
Lot's of drivers have never had the experience of driving a car without FI, PS, PB, AC, automatic transmission and other features that are now stand equipment on almost all new cars until they buy an old collectible. Even if everything works as designed on an old car, newb drivers tend to think there is something wrong with the car.
This has been an informative read for me. I've been pumping before cranking on a cold engine, but hadn't been waiting before cranking. Tried that yesterday and wow! It fired up instantly. Thanks for the tip!
Why would you be doing "hole shots" with a cold engine anyway?
Seems like that might be hard on equipment whether you had a choke and/or heated intake?
Lot's of drivers have never had the experience of driving a car without FI, PS, PB, AC, automatic transmission and other features that are now stand equipment on almost all new cars until they buy an old collectible. Even if everything works as designed on an old car, newb drivers tend to think there is something wrong with the car.
Yup! Best to let the oil temp get up to 150* or so before puting much stress on the engine.
09-16-2018, 06:53 PM
