302 revs and dies

[sdbuggyboys]

So, I've been working on getting a 302 running in a bronco I bought recently and I've been having issues. I wanted to do it with as little hassle as possible so I bought an HEI Distributor so I only have to run one wire to it. Put the new distributor in and turned it over, now it starts up and revs like crazy and then dies. I seem to be able to control it with the carb between like 4000-6000 RPM (I know, way high), but as soon as I let off it dies again. I know it sounds like a giant vacuum leak, but wouldn't one that big be something I should be able to clearly hear? Also, some other random info, like I said I'm trying to get it running as cheaply and easily as possible until I can see what else needs work so I basically plugged all the vacuum ports and ripped all unnecessary wiring out until I get it running. I know it ran just a few years ago, what could be wrong with it? It sounds like vacuum, but I'm wondering if I'm just way off in timing somehow?

 

[Broncobowsher]

Did it run/idle with the old distributor/ignition?
Did you remove the EGR valve? (whole valve/spacer under the carb, not just unplug the vacuum line)

 

[sdbuggyboys]

No idea, the PO was in the middle of doing body work so the dash and all the wiring was ripped out so I ran a wire to the starter and one to the distributor, but it sounded like it was running fine when he had it together. I haven't tried the EGR yet, that's next.

 

[jckkys]

Did you replace the stock distributor having no reason to believe there was a problem with it? Why? It's cheaper to run what came with the engine than buy an after market ignition. Was the original the point type or Duraspark electronic? What else was changed since it ran well for the PO?

 

[sdbuggyboys]

I bought a new ignition because all the wiring had been ripped out and I didn't want to try and re-wire everything. Checked the carb and it looked fine, even took a carb off of my running one but that didn't fix it. I'll check the EGR when I get a chance. And yes, 4000-6000 with straight pipes sounds like a dragster

 

[jckkys]

You know you have a spark, fuel, and air. When you partially close the throttle and the engine dies, does it do it suddenly or sputter while spewing black smoke or shudder to a stop. The point is, the mixture is either too rich or too lean to support combustion.

 

[sdbuggyboys]

Suddenly, like someone turned the key off.

 

[sdbuggyboys]

But if I put a carb on it that I know works, why would too lean/rich be an issue?

 

[jckkys]

Lean could mean a vacuum leak. I think the reason Broncobowsher asked about the EGR is that carburetor spacers with EGRs on them can't be replaced by none EGR spacers without creating huge vacuum and exhaust leaks. The same thing if the EGR valve is removed from the spacer. The exhaust hole in the EGR intake's carb mounting pad is outside the sealing surface of the none EGR spacer. A PVC port left open or not connected to to the PVC valve can do the same. An engine just suddenly dying implies an ignition issue.

 

[sdbuggyboys]

OK, that makes sense. From what I've heard, the EGR could be stuck wide open. Here's my plan, I know the extra carb and EGR I have do work, because I had them running on an engine not too long ago. I've replaced the carb, but not the EGR so I'll put the carb and EGR that I know work on the engine and see if that works. If it doesn't, at least I've eliminated something. Then I'll double check the timing and make sure that the problem isn't ignition related. If not, maybe pull the intake and see if the gasket got sucked into the valley maybe?

 

[sdbuggyboys]

Just in case anyone ever reads this again, it was the spacer between the EGR and the carb. Its made of a cardboard material and had started to separate a bit between the layers which resulted in a "second air filter" sucking in air but no fuel Replaced the spacer and she purrs like a kitten.

 

[jckkys]

That's good news.