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Old 03-11-2013, 12:46 PM   #1
Buzzman
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Bad starts when warm...heat soak? Carb?

Hey there,
(350 with Edelbrock intake and original 4bbl Q-jet)
Having some issues starting when the motor's nice and warm. For instance, when driving around all day, running errands, if I stop for 15 minutes somehwere and come out, the truck has a hard time starting. It turns over, but I have to give it some gas to get going. In the morning, or after sitting for a while (hour-plus), it fires right up.
I've done a little research and it seems that it might be starter heat-soak, as the exhaust downpipe does run pretty close (ramhorns). A mini starter/heat shield might fix this. The other possiblity would be something with the carb - it almost feels as if it's flooded, or the gas is getting too hot from the intake -some folks have mentioned a carb spacer to help with this.
Anyhoo, sorry for the long post. Any tips? Thanks.
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Old 03-11-2013, 03:36 PM   #2
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Re: Bad starts when warm...heat soak? Carb?

Edelbrock afb carbs are notorious for having hot start issues. Wouldn't surprise me if that was an issue
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Old 03-11-2013, 07:07 PM   #3
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Re: Bad starts when warm...heat soak? Carb?

I've heard that, too, but mine's the stock Q-Jet. The more I read, it sounds like I should just try a spacer.

Anyone else?
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Old 03-11-2013, 07:13 PM   #4
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Re: Bad starts when warm...heat soak? Carb?

the alum intake transfers the heat to the carb , so you are right on , with the spacer
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Old 03-11-2013, 07:46 PM   #5
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Re: Bad starts when warm...heat soak? Carb?

Heat soak of the starter will give you a hard,laboring crank ,definitely sounds fuel related.Had that problem on a lot of passenger cars in the 80's when they started introducing ethanol blended fuel,lowered the boiling point I think,fuel would boil in the carb,spilling over into the intake,the thing would be flooded and the carb would be empty till the fuel pump caught up.
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Old 03-11-2013, 07:51 PM   #6
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Re: Bad starts when warm...heat soak? Carb?

Mine has the same issue. I'm running a edelbrock. I was told it is a combination of the new crappy fuels evaporating faster in the carb and the heat off the intake. My friend said a aluminum intake with a spacer is the way to go. The 80 rally sport camaro had a edelbrock aluminum intake, carb and 1in spacer and never had the issue my truck has with its factory intake. That swap is on the list.
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Old 03-11-2013, 07:58 PM   #7
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Re: Bad starts when warm...heat soak? Carb?

Right, it's gotta be a combination of the stock Q-Jet and the aluminum intake. I think the aluminum must conduct heat a little better than the old cast-iron. Spacer it is... Thanks guys.
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Old 03-11-2013, 08:27 PM   #8
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Re: Bad starts when warm...heat soak? Carb?

Timing might be set to far advanced, might bump it back a lil? Just my .02 cents
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Old 03-11-2013, 08:46 PM   #9
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Re: Bad starts when warm...heat soak? Carb?

I have the same problem,edelbrock performer intake and edelbrock 600 cfm. Should I add a spacer?
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Old 03-11-2013, 09:32 PM   #10
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Re: Bad starts when warm...heat soak? Carb?

Quote:
Originally Posted by wiskers View Post
Timing might be set to far advanced, might bump it back a lil? Just my .02 cents
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Old 03-12-2013, 01:16 AM   #11
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Re: Bad starts when warm...heat soak? Carb?

Do you have an electric choke on it? If you do, I will bet it is engauging when it isn't supose to. The choke will also keep the secondarys from opening, so after you start it when it is warm, floor it and see if the big boys dump.
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Old 03-12-2013, 04:27 AM   #12
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Re: Bad starts when warm...heat soak? Carb?

Aluminum intakes and whether it be an Edelbrock carb or another brand, there are some issues with the fuels of today. The amount of alcohol within the gas causes it to evaporate quickly on a hot day. If your fuel line is metal and it runs close to the head or upper radiator hose, that will also cause vapor lock issues. If your fuel pump does not have a return line to the fuel tank, there is another place the fuel will boil away.

I put a phenolic spacer under my carb, I made sure my fuel line was clear of all heat soak areas, and I put a new bottom plate on my edelbrock fuel pump to get the extra openings and made sure that my return line to the tanks was working. It solved the majority of my heat/vapor lock issues on my stroker engine.
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Old 03-12-2013, 01:54 PM   #13
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Re: Bad starts when warm...heat soak? Carb?

Choke is the stock hot-air version attached to the intake - I think it's working fine.

I think I'll check the timing, put the spacer in, and make sure all lines are clear of the exhaust and whatnot. Just put a new fuel pump in, so the return line should be good. Thanks for the help everyone!
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Old 03-12-2013, 05:01 PM   #14
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Re: Bad starts when warm...heat soak? Carb?

Quote:
Originally Posted by piecesparts View Post
Aluminum intakes and whether it be an Edelbrock carb or another brand, there are some issues with the fuels of today. The amount of alcohol within the gas causes it to evaporate quickly on a hot day. If your fuel line is metal and it runs close to the head or upper radiator hose, that will also cause vapor lock issues. If your fuel pump does not have a return line to the fuel tank, there is another place the fuel will boil away.

I put a phenolic spacer under my carb, I made sure my fuel line was clear of all heat soak areas, and I put a new bottom plate on my edelbrock fuel pump to get the extra openings and made sure that my return line to the tanks was working. It solved the majority of my heat/vapor lock issues on my stroker engine.
Is a phenolic spacer made of some sort of wood . I have a wooden spacer on mine & was told they did the best job of heat retention . Just cant remember if they said it was phenolic or not , Will
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Old 03-12-2013, 05:03 PM   #15
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Re: Bad starts when warm...heat soak? Carb?

Phenolic is some king of high-density, space-age plastic. Apparently it's head resistant and doesnt shrink or warp. We'll see!
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