LSM360
Well-Known Member
This could be a problem. I would definitely do a fuel pressure check now. See if it's stable, what it is at idle and with revs as well.
Warm start issues
- Thread starter JBFury
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Aspen500
Well-Known Member
I have a 1/2" wood composite spacer under my Aspen's carb and it did wonders for the hot soak deal, and it uses premium, which is all ethanol free around here. Way better than the previous 1/4" fiber gasket did. In fact, I haven't had any trouble since. Sounds weird saying the carb spacer is wood, lol.
80CordobaLS
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Yes, make sure the choke isn't closing on a still-hot engine.
Just to clarify, true vapour lock is when the mechanical fuel pump gets so hot that the fuel 'boils' inside the pump under vacuum and so won't create suction to pull any fuel in to pump. Pouring water on the pump will show if that is the problem.
What you likely have is fuel evaporating into the carb bores making a super rich mixture, I think they call it 'heat soak' but correct me if I'm wrong. Several things you could test. Let it happen as it normally would, try to start the car, and a second or two after it fires up turn it off. Now inspect the plugs and see if they are wet and/or black with soot.
So you have access to an IR temperature gun? See what the temperature of the carb is after the usual 30 minute heat soak when it won't start. Compare that to the carb temp after sitting only 10 minutes.
Do you have a proper thick insulating gasket between the carb and the manifold? Just a single thin gasket can lead to this problem.
Ethanol is only 20% of the fuel mix. Even if all the ethanol boils out of the carb it should still be 80% full of gasoline.
That wood spacer is an excellent suggestion. Make one yourself. I used Baltic birch, or cabinet grade plywood as the best choice.
Just to clarify, true vapour lock is when the mechanical fuel pump gets so hot that the fuel 'boils' inside the pump under vacuum and so won't create suction to pull any fuel in to pump. Pouring water on the pump will show if that is the problem.
What you likely have is fuel evaporating into the carb bores making a super rich mixture, I think they call it 'heat soak' but correct me if I'm wrong. Several things you could test. Let it happen as it normally would, try to start the car, and a second or two after it fires up turn it off. Now inspect the plugs and see if they are wet and/or black with soot.
So you have access to an IR temperature gun? See what the temperature of the carb is after the usual 30 minute heat soak when it won't start. Compare that to the carb temp after sitting only 10 minutes.
Do you have a proper thick insulating gasket between the carb and the manifold? Just a single thin gasket can lead to this problem.
Ethanol is only 20% of the fuel mix. Even if all the ethanol boils out of the carb it should still be 80% full of gasoline.
That wood spacer is an excellent suggestion. Make one yourself. I used Baltic birch, or cabinet grade plywood as the best choice.
Looking into and following-up on the variety of suggestions I've received, I agree that heat soak is the culprit. The insulating gasket is quite thin and I will be upgrading next chance I get. As someone else noted earlier, I can get an initial start up most of the time but have to hold the throttle down a bit to lean out the mixture before it will stay idle without stalling out. If it stalls out then that's when re-starting becomes a chore (starter fluid saves the day usually if I'm really in a pinch).
Got a saw and some drill bits?
I hadn't seen one for sale commercially, but with some time and effort, you can make your own. A Jigsaw and/or band saw will help.
It would be better to make one out of hardwood than plywood. Better for an evenly dense wood like Cherry or Walnut than Oak (sense Oak has porous rings, for example). Any wood will swell when wet, which will prevent leaks.
Take a gasket and draw the outline onto the wood. Drill the holes first - sense the four holes are maybe the biggest issue to get correct. If you drill a mounting hole in wrong location, you will need to start over. Once the four holes are good, then drill a hole in the middle and use a jigsaw to cut out the middle part with, A course file to smooth things up, then sandpaper to finish off with.
Don't use any finish on the inside - for gasoline or cleaners will remove any finishes.
I would put something on the outside of the wood, and several layers of engine paint might be best. Wood stain might also work. A urethane finish will not work (it will desolve in no time)! If you got any paint on the gasket surface, then sand it off (and don't leave paint on a sealing surface). Use a thin gasket on top and bottom and you are set.
It will not matter if the wood plate is warped or not - for it will straighten out once tightened down. The important part is top and bottom are parallel to each other.
If you are using a divorced choke (choke attached to intake manifold) - then a person will need to find a way to get the choke adjustment down correct. Even having a slightly thicker gasket is enough to get the choke settings off - not counting a 1/2 inch (or whatever height) spacer added.
One last thing. you might need longer fasteners (bolts or studs).
I have a 3D printer and could make one - but I don't think plastic would be adviseable here (melt from heat or melt from gasoline contact).
BudW
I hadn't seen one for sale commercially, but with some time and effort, you can make your own. A Jigsaw and/or band saw will help.
It would be better to make one out of hardwood than plywood. Better for an evenly dense wood like Cherry or Walnut than Oak (sense Oak has porous rings, for example). Any wood will swell when wet, which will prevent leaks.
Take a gasket and draw the outline onto the wood. Drill the holes first - sense the four holes are maybe the biggest issue to get correct. If you drill a mounting hole in wrong location, you will need to start over. Once the four holes are good, then drill a hole in the middle and use a jigsaw to cut out the middle part with, A course file to smooth things up, then sandpaper to finish off with.
Don't use any finish on the inside - for gasoline or cleaners will remove any finishes.
I would put something on the outside of the wood, and several layers of engine paint might be best. Wood stain might also work. A urethane finish will not work (it will desolve in no time)! If you got any paint on the gasket surface, then sand it off (and don't leave paint on a sealing surface). Use a thin gasket on top and bottom and you are set.
It will not matter if the wood plate is warped or not - for it will straighten out once tightened down. The important part is top and bottom are parallel to each other.
If you are using a divorced choke (choke attached to intake manifold) - then a person will need to find a way to get the choke adjustment down correct. Even having a slightly thicker gasket is enough to get the choke settings off - not counting a 1/2 inch (or whatever height) spacer added.
One last thing. you might need longer fasteners (bolts or studs).
I have a 3D printer and could make one - but I don't think plastic would be adviseable here (melt from heat or melt from gasoline contact).
BudW
80mirada
Well-Known Member
Summit Racing, Speedway, Jeg's, and Amazon have wood spacers readily available.
Cool beans!
LSM360
Well-Known Member
He's correct! Wood is supposed to be the bestest. I had a wood one on my old Diplomat with crate engine after several smarter than me people recommended wood for heat dissipation. I wood (lol) have one now but I have an air gap intake and wouldn't have hood clearance.
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err, not for wood but for metal?
A person might look at an active cooling system like a small electric fan (or two) mounted under the air cleaner, that turn on for say 10 minutes after vehicle turn off.
There are active and passive cooling methods. The wood block is a great passive method - but in some cases, a person might have to look at other methods.
One of the best things about going to fuel injection is the electric fuel pump eliminated a lot of these problems - which might be something to look at, as well.
Even a cheap low pressure electric pump in place of existing fuel pump might fix this problem. Well, I don't know about fixing it, but it will at least fill the carburetor before cranking.
A person can use the car-on power feed - but I would use a relay using battery voltage instead of overpowering the ignition system circuitry.
BudW
