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Hard to start after short drives

66/75bronco

Jr. Member
Joined
Jan 5, 2008
Messages
102
Loc.
Redfield Arkansas
I've got a 69 stock 302 3sp that has a problem. After a 10 mile or so drive it doesnt want to restart. From searching threads I think I know that the gas is boiling in my carb but I dont know how to fix it. I've got a spacer under the carb and thats about it. I dont want to cut my wheel wells and need you guys help. Hood scoop? Thanks.
 
OP
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6

66/75bronco

Jr. Member
Joined
Jan 5, 2008
Messages
102
Loc.
Redfield Arkansas
When I try to start it, it acts like its flooded and I have to crank on it quite a bit. The spacer is the one that came with it. Is there a special heat spacer?
 

VT_Don

Sr. Member
Joined
Aug 16, 2001
Messages
365
I am very familiar with this issue having suffered with it in both my Mustang and Bronco. When parked after use, heat radiating off the exhaust manifolds, and conducted thru the intake will boil or "percolate" fuel flooding the motor.
First, make sure float setting is correct and needle valve seat is perfect. Not uncommon to see the fuel line against the block become so hot it pushes fuel past the bowl seat. Add a phenolic spacer between the intake and carb. 1-inch thick if you have space, or 1/2" otherwise. Block off the exhaust crossover in the intake. Run the fuel line away from the block to keep it as cool as possible. Use a fixed blade fan without a clutch. Same as short track modifieds. Keep as much cool air as possible moving thru the compartment when running. Cooler it is before parking, cooler it will be after. Don't be ashamed to open the hood when parked. Is a honor sign of hard core street racers.
P.S. Information here is worth exactly what you paid for it.
 

oleguy74

Bronco Guru
Joined
Mar 26, 2008
Messages
2,034
Loc.
calif city ca
When I try to start it, it acts like its flooded and I have to crank on it quite a bit. The spacer is the one that came with it. Is there a special heat spacer?

if you don't have one,put a clear fuel filter between pump and carb.if you have a bad check valve in fuel pump,fuel will siphon back.if filter has fuel in it,then look at evap/boiling fuel out of carb.they make fiber spacers.
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
Good advice.
I also lower the float level a bit. I've had the same issues. If you're using a mechanical fuel pump, the fuel in the line between the pump outlet valve and the carb needle valve gets hot, expands, and overcomes the needle valve. This overflows the float bowl. The reason this wasn't an issue back in the day when these vehicles were new is the fuel is different now. The vaporization point is lower and it boils pretty easily. The problem gets even worse at higher elevations because there is less atmospheric pressure and so the boiling point is even lower. This is also why vapor lock is more of a problem with carbed vehicles.
 
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6

66/75bronco

Jr. Member
Joined
Jan 5, 2008
Messages
102
Loc.
Redfield Arkansas
Thanks guys. I'll make sure my fuel line is away from the block and check out the spacer. Its got a new fuel pump and carb do I still need to check the needle seat? How do I adjust it? Its an autolite 2100 rebuilt from parts store.
 
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