car started breaking up, then died, wouldn’t restart until cool
07-03-2023, 05:00 PM
#1
car started breaking up, then died, wouldn’t restart until cool
hey guys. just finished getting my car all back together. it is an 86 trans am that was originally a tpi but now has a 383 stroker, edelbrock 750 carb, performer rpm air gap intake, xe282hr cam, stock fuel pump with a mallory fuel regulator set to 4-6 psi, dui distributors hei, brand new air damn in great condition, 180° thermostat.
the car always starts up, runs great, stays cool at idle. today was the first day i took it on a drive and it was relatively hot out. about 20 minutes into the drive i noticed a slight break up at 4500rpm. the car was approaching 210° which is hotter than it ever gets idling in park.
i was on the way to the gas station so i shut it down and filled the tank. the car started right back up at the gas station, on my way home i noticed it slowly start breaking up at 3500rpm, and then occasionally it would have a hiccup every now and then around 2500rpm. it finally shut off while going down the road and let out a very loud backfire from the exhaust. the car would not restart and would just crank, occasionally sputtering and wanting to fire off so i know it had spark at least. the temp was probably around 210-220°
i get it towed back to my shop and start looking it over, i turn the key and it fired right up. i check compression in all cylinders because the backfire sounded bad and had me worried but all cylinders were within 10% of eachother. i pull the valve covers and all looks fine. the plugs were a nice golden brown, all of them looked identical.
the car is currently running fine like it always has idling in park, i’m nervous to take it for a test drive again. i was reading about carb heat soak and percolation so i put an edelbrock phenolic spacer on that autozone had in stock. the carb was very hot to the touch when it broke down. when it eventually turned back on i heard the metering rods tapping against their cover plates, is this a sign of something? the carb is an edelbrock 750 14073 with all stock hardware on it. i did rebuild it a few months ago and set the floats with a 7/16 drill bit as instructed. i really want to think the carb got heat soaked but figured that’s unlikely with an air gap intake. the carb was too hot to touch though.
curious if anyone can think of something i’m overlooking?
the car always starts up, runs great, stays cool at idle. today was the first day i took it on a drive and it was relatively hot out. about 20 minutes into the drive i noticed a slight break up at 4500rpm. the car was approaching 210° which is hotter than it ever gets idling in park.
i was on the way to the gas station so i shut it down and filled the tank. the car started right back up at the gas station, on my way home i noticed it slowly start breaking up at 3500rpm, and then occasionally it would have a hiccup every now and then around 2500rpm. it finally shut off while going down the road and let out a very loud backfire from the exhaust. the car would not restart and would just crank, occasionally sputtering and wanting to fire off so i know it had spark at least. the temp was probably around 210-220°
i get it towed back to my shop and start looking it over, i turn the key and it fired right up. i check compression in all cylinders because the backfire sounded bad and had me worried but all cylinders were within 10% of eachother. i pull the valve covers and all looks fine. the plugs were a nice golden brown, all of them looked identical.
the car is currently running fine like it always has idling in park, i’m nervous to take it for a test drive again. i was reading about carb heat soak and percolation so i put an edelbrock phenolic spacer on that autozone had in stock. the carb was very hot to the touch when it broke down. when it eventually turned back on i heard the metering rods tapping against their cover plates, is this a sign of something? the carb is an edelbrock 750 14073 with all stock hardware on it. i did rebuild it a few months ago and set the floats with a 7/16 drill bit as instructed. i really want to think the carb got heat soaked but figured that’s unlikely with an air gap intake. the carb was too hot to touch though.
curious if anyone can think of something i’m overlooking?
07-03-2023, 05:37 PM
#2
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Car: 92 Firebird, 77 Trans Am SE, 86 Z28
Engine: 5.7 HSR, T/A 6.6, empty
Transmission: T-5, TH350, T-5
Axle/Gears: 3.08 posi, 3.23 posi, 3.23
Re: car started breaking up, then died, wouldn’t restart until cool
Since you're suspecting it being too hot, which I'm inclined to look into the same thing, then get a temp gun or some sort and check and confirm what temperatures is where. Before the regulator you certainly shouldn't have a fuel boiling problem but at the bowl would be a concern, how hot is the carb really? Like the actual degree. What kind of gauge are you using? I usually don't trust them as a source of legit information, especially the factory. What are you using for fans? Are they kicking on? I don't think I've said anything you already haven't thought about.
07-03-2023, 05:56 PM
#3
Re: car started breaking up, then died, wouldn’t restart until cool
Since you're suspecting it being too hot, which I'm inclined to look into the same thing, then get a temp gun or some sort and check and confirm what temperatures is where. Before the regulator you certainly shouldn't have a fuel boiling problem but at the bowl would be a concern, how hot is the carb really? Like the actual degree. What kind of gauge are you using? I usually don't trust them as a source of legit information, especially the factory. What are you using for fans? Are they kicking on? I don't think I've said anything you already haven't thought about.
the cooling system is the stock single fan running off a fan controller that’s set to come on around 170° i believe, the radiator is a frostbite two core aluminum radiator. i am currently thinking about doing the crown vic upgrade after this. the car never got hotter than around 210° but it also didn’t have the chance to get any hotter
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