I'm running an Edelbrock 750 cfm carb on a Buick 401 nailhead. My problem is that when the engine is hot, its hard to start and requires turning over for some time before it will catch. Anybody have any solutions for this ? All help is appreciated.
It's a common problem with Edelbrocks and todays gas. I suspect other brand carbs have this problem as well, but due to the volume of Edelbrock owners it seems to be the one you hear about all the time. My recommendation is pull the 401 and install a flathead. LOL A lot of guys report a heat shield or spacer works to cure the problem. It didn't for me in a 56 Chevy I used to town, but that's me. I guess I'm the only one it didn't work for.
Yea put a cloths pin on your fuel line. Could be any number of reasons that it won't start, when you say hot how hot for example? Hot enough to boil the ethanol out of the float bowl? Does it turn over slow like the starter is dragging? Does the fuel line run close to the exhaust? Electronic or pints ignition? If electronic is it a bastard unit or a known unit like a petronix or mallory ( and etc). What about the coil, how and where is it mounted? Is it getting smokin' hot? Does it even pop or fart when it is being spun or just grind along then finally start? Not being an ass here or not trying to just that if any of us are going to trouble shoot your engine for you from our desk we need more info that you have given us?
Great article by Gerry Burger in the latest Street Rodder mag on this type of problem. Ethanol and heat are the culprits. Solution is heat control devices and more frequent carburetor maintenance. Great article, Gerry!
I have the same problem in a 350 SBC, 500 Edelbrock carb. After a good long run to thoroughly heat up the engine, shut it off and try to restart it within one minute, it won't start. After a minute (timed minute), it starts right up. I'll try a spacer & see what happens. Thanks, -Bob
Assuming it is a fuel related problem, a carb spacer/insulator might be the simple fix. The next time you shut the engine off you might try looking down the carb after a few minutes and see if there is fuel puddling up on the throttle plates or the floor of the intake manifold. Is there any sort of a bowl vent adjustment that might have been overlooked? Do you have a working choke and is it adjusted properly? Is the choke unloader properly adjusted?
In addition to adding a spacer, recommend checking your carb float level. If it's set high, as heat sink sets-in when you shut the engine off, the gas will spill over into the manifold causing hard starting and possible flooding. I had the same problem on my 55 F-100 and after lowering the float, the problem went away. Good luck and hope you are able to resolve this annoying problem; especially since the summer heat will be setting in. Steve
Had the same problem with my 383....ended up being a coil on its' way out......once it got hot it didn't want to throw a strong spark
Several good answers here. it's not a nailhead problem and it probably isn't a brand of carb problem but a driveability problem. That means carb adjustment, ignition (timing, coil, points if it has them and general condition) and as several said the possibility of the engine heat boiling the crap corn fed gas we have to put up with.
I had the same problem-turned out to be a bad ground with the battery. Cleaned up the metal on the frame, put on a bigger ground cable (2 ga.) and she cranked like a new car. Posted using the Full Custom H.A.M.B. App!
I put the phenolic spacer in to fix it, the gas just boils out of the bowls. After it gets hot and before you try to restart pull the horn off and look at your bowls to see how much fuel is in then. You could also try dripping a little gas down the carb to see if it starts easy, proving a low fuel condition.
Two options, guess and throw parts ( aka money at it) Listen to beaner, give us some more info we can guide you to trouble shooting and fix the problem right. you will gain some understanding, then you will be able answer some of these questions for other guys instead of asking them- & that's a good thing. Next time it doesn't start, Determine if its fuel related or ignition/spark related. There's a 5.00 spark checker available that visually shows the spark. There's a 5.00 can of starting fluid or carb cleaner too. If its not starting but a squirt gets it going you have now determined the cause & a direction
Now that the weather has warmed up, my temp runs anywhere from 160 to 200 F. This problem only happens when its at the 200 Mark. I have an electric fuel pump, new carb, new petronix ignition and a new coil. The engine turns over fine, even when hot. I'm running a mini starter, so it cranks real good. If I give it a shot of quick start, It fires right away. I will try the spacer thing and see what happens. Thanks for all the help.
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I had the same problem with my old 58 Ply 318 I went to look at a 383 to transplant and it would not start. The guy said wait here and went into his shop, pulled out CO2 fire extinguisher and built up some frost on the intake mounted coil. He said now start it. It lit right off. I had tried all the clothes pin and tin foil tricks. Na da This was in the days of 260 Sunoco so the modern gas was not a problem. Borrow a coil before you buy one. I hate to throw $ parts at it until it starts I bought the 383 and did my first engine swap in the back yard .4o some years ago.
Since you have an electric fuel pump you might try letting the fuel pump run for a few seconds before trying to start it. If the fuel is boiling out of the bowl due to the heat you may need to let the fuel pump refill it before cranking on it.
I had the same problem. Replacing the 450 CCA Optima Yellow Top battery with an Interstate AGM with 800 CCA took care of that problem and quick!
We used the wooden clothespins on a stock car that tended to vapor lock after a warm up or heat race and be damned.. it worked. The phenolic spacer should help out, but cheap and easy enough for a probable cure. We used to add a thin aluminum shield between the carb and spacer to deflect some of the heat off the intake manifold. Not sure how well it worked but looked pretty trick. Bob
Tommy When I was in Mexico one of the fellas had a Ford that would not start or run worth a flip when I was hot. One day he was busy beating on the intake with a hammer because his grandpa had and old ford and when it wouldn't start that was what he did. This Mexican guy walked up and asked me if I had a rag so I said sure, he dipped it in a mud puddle and wrapped it around the coil. Told me to get in and start it, it lit right off. Then he asked us for a ride.
I have a 600 Edelbrock and was having the same problem ,put a spacer under it and it helped but not always .I was at a venders show and talked to a Lucas oil Rep. He gave me a bottle of Lucas Ethanol Treatment and said to add between 3 and 5 ounces initially then 2 to 3 ounces every other tank..He said it is the ethanol in the gas that is causing the hard starts in most older cars.. I don't like additives ,but 2 tanks later and my problem seems to be solved .A bottle is about ten dollars and will last 2 months .My 2 cents
I have a high torque starter and it spins just fine. A racing buddy suggested that I plug the exhaust heat holes under the carb with JD Weld. He says that the gas is being boiled off. I am going to install a spacer also. This problem only happens when the car is super hot, i.e. 200F. Thanks for all the suggestions
There's a pretty simple fix, if it isn't a hard cranking issue, but rather just cranking too long. I've had engines that were built beyond factory specs that started harder when hot. I simply put a switch on the coil circuit to shut it off while cranking. Hit the starter, and after the engine makes a couple turns I turn the coil on and they fire right off. Sometimes all the tuning I tried didn't help, but this worked perfect on a hot start.
Good move...I would say better than the 12V jump wire GM normally includes in their older harnesses. I had a customer with a '28 'A' Phone Booth P.U., w/Buick nailhead that 'starter-dragged' unmercifully when hot. After some preliminary tests, (amp draw was 300) I looked further. Turned out his 'Super 401" Nail' was tapered in the cyls to the tune of .012"! ...A simple rebore and a set of J.E. pistons had it spinnin' like a top! Lotsa miles, and they do get 'tired'...
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