318 Runs Crappy at low speeds when hot.

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hdfattboy2001

hdfattboy2001

Never Enough Cars!
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Hello Everyone, my barracuda all summer has been falling on its face once it heats up to full temp. (180ish) Its a 318 with mild cam/headers, holley double pumper...All new autolite plugs, MSD wires etc. I can take off and the thing runs sweet out of the gate, will cruise awesome all day at 45+ MPH, but once I start hitting towns and running into stop signs etc it has a nasty miss, it feels similar to if a spark plug wire is loose etc... Sometimes if i put my boot into it and let it kickdown it will run run fine again when i get to my highway speed driving. Any Ideas on where to look? Is it possible my ignition box is taking a crap when it gets warm?

Thanks,
Brad
 
make sure the timing is set correct...make sure the pickup coil gap in the distributor is correct...

check the float level on the carb...do you have a fuel pressure gauge...

what thermostat do you have in it...?
 
I was dealing with what I thought was a miss, but turned out to be a fuel pump going bad. It ran great off the line and cruising but as soon as I went over 35-40 mph it had a weird sputter. might be something to look into, plus its an easy and cheap fix.
 
i forgot the term but maybe the headers are evarperating the gas away if your gas line or fuel pump is close to your headers or manifiold.....
 
Sounds to me like fuel related, IE vapor lock

Take a look at your fuel line routing, check your pump pressure and.......

CONSIDER A VAPOR RETURN SYSTEM.

If you have a late car with a pressure / vacuum cap, you might try getting a VENTED cap instead.



If you've disconnected the carbon canistor, you'll have a free tube from front to rear. You can buy two Wix filters, 33041 I believe is 3/8, and Wix makes a 5/16 as well. These two filters have a third 1/4" fitting which is designed for vapor return. Just plumb that third 1/4 fitting back to the tank.
 
Check for garbage in the low speed circuit of the carb.
 
I have a fuel problem as well usually when its hot I have a but load of build up in the tank you can hear the pressure escape thru the cap and when I take the gas cap off sometimes at the gas station I take the cap off It wants to blow my cap away because of all of the pressure in the fuel system how can I solve this.. sorry for hijacking the thread
 
When it gets hot and you shut it off for a minute. Will it start right back up ?
 
Found it! Unbelievable, the #7 Plug wire had a burn in it and was grounding to my header! When I changed my plugs the other day i looked over the wires which are only a year old, BUT i must have overlooked this boot because I had a high temp sleeve over it to protect it from the stupid header! I cant believe how much tail chasing i was doing for something so easy!!!!!!!



Thanks for the help guys!
 
WooHoooo, So many times I've seen problems blown into stuff way to complicated when it's just so basic. Hey, these car are simple, stick to the simple stuff.
 
duster731 said:
I have a fuel problem as well usually when its hot I have a but load of build up in the tank you can hear the pressure escape thru the cap and when I take the gas cap off sometimes at the gas station I take the cap off It wants to blow my cap away because of all of the pressure in the fuel system how can I solve this.. sorry for hijacking the thread
Click to expand...


You need to vent the tank, try a vented gas cap.
 
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