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Discussion Starter · #1 ·
Kind of off-topic I guess, but I've seen others ask carb questions (if it's even a carb problem.)

It's the motor in my stockcar that I'm still trying to fire to break in. I just cannot figure out this damn starting problem. Engine fires with a little bit of throttle, runs for about 5 seconds, sounds fine, then coughs and sputters and dies. Restarts perfectly every time.

It's a Holley 4412-1 with one of those newer non-adjustable floats. Off the shelf. No dirt or varnish whatsoever. I took the fuel bowl off anyway but everything looks perfect, turn it upside down and the float is perfectly parallel to the body of the bowl. Needle/seat move fine. All other settings are factory default. Choke is removed. Every vacuum port I could find, including the one for the choke, is blocked off.

Fuel pump is fine. I can't imagine a vacuum leak being big enough to prevent it from running at ALL after a few seconds--and since the engine doesn't run long enough, I can't really spray for a vacuum leak anyway.

I don't see how it could be ignition related either? It would still run, it'd just run poorly. The engine actually sounds pretty good for the 5 seconds it runs. The valve lash hasn't been set yet, but again, if it runs at all I don't see that being the issue either.

Any thoughts? I'm worried if I keep trying this over and over, I'm gonna end up wiping the cam, it hasn't run long enough to break it in.
 

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Fill a soda bottle with some gas, have someone start it, and be ready to give it splash of fuel as soon as it starts to sputter. If it keep running, then it's fuel delivery. I don't know that carb, but there is more to a carb than just having a little fuel in the bowl. It needs a certain level of fuel in the bowl to feed the idle and intermediate circuits through the emulsion holes and such. The fact that it starts fine and runs for a brief moment indicates that it's something like fuel starvation. Is the bowl vented? Is the vent clogged such that air can't get out to let more fuel in? Sorry if I'm not much help, it's hard to know without seeing it first hand.
 

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Discussion Starter · #3 ·
Now that I think of it, I don't know where the fuel bowl vent is. And I can't see it on the exploded diagram. Guess I'll take a look at that first.
 

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And don't _fill_ the bottle with gas. Just use a little bit to test for fuel delivery. If you pour some fuel down the carb when the engine starts to sputter, and it backfires, you could end up with gasoline all over the place.

It could be an ignition issue. I had a problem with our 68 Caddy that seemed to be fuel related. I could drive the car around a bit, and sometimes, it would just die. Since the car was out at a storage lot, it was usually low on fuel. I'd dump a gallon, or two of fuel in it and it would usually start right up. One time it did it, I fueled it, and it didn't start. Checked and discovered I had all the fuel in the carb I needed. I swapped in a new coil, figuring the OEM coil was overheating and grounding out. No start. I eventually tuned it up. When I pulled the integtrated points/condenser, the points looked pretty used up, with a peak burned into one of the points, and a divot in the other.

After the new plugs and points were installed, I've had NO problems with the engine quitting since.

Hook a timing light to the car and see if you still get a signal when trying to start it after it dies. If so, I bet you're looking at some fuel issue.
 

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Discussion Starter · #5 ·
Well we got it running, just by persisently flooding it (not literally) with gas, and now it runs. Broke the cam in, 2000 rpm for 10 minutes. During that time, the water temp hit 200 and the overflow bubbled a little. It was sitting in my shop of course, and I have no fan shroud, but that still seems awful hot for just 10 minutes... I set the timing barely by ear though, so I'm going to put the timing gun on it tomorrow night, I thought I heard a little pinging, but the plugs looked fine. Would explain the heat. Thanks for the tips though, clearly it was just needing more and more fuel for that first throat-clearing.
 

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I had a 71 455HO I rebuilt, and to start it, I had to put drilled out jets in the carb. After break-in, the more I ran the engine, the more I had to lean it out. Seemed to need a LOT of gas to start (and the headers would glow red after 5 mins of running), but it got better.

Yeah, the engine may still be a bit lean, which can also contribute to the heat.
 
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