Been pulling my hair out for weeks on this... worried I'm gonna flatten my cam messing with getting this thing running for break-in!

74 Bronco, newly rebuilt 308, .040 over, decked, 10.5:1 SC, aluminum heads with guideplates, hardened pushrods, Lunati mild RV FT cam (like .480 lift) and new Lunati hydraulic lifters, Edelbrock 1406 on Holley manifold, longtube headers, complete new wiring, new battery, new Duraspark Module and Distributor (Cardone Chinesium copy), new coil, new tank, fuel pump and fuel lines.

After reading about all the nightmares online, I was super nervous about breaking in the cam, so I primed the oil pump, added lots of timing (with vacuum advance connected), and put 3 fans on the engine to keep it cool. I've started it 8-10 times now and it won't run for more than 2-3 minutes before stalling. The first several times, it starts immediately and run straight up to 2200 rpms, while I tried to dial in timing to 28 btdc at 2200 rpms, and it still keeps dying after a few minutes. So I capped my vacuum lines and went to straight mechanical (set at same 28 degrees by 2200 rpms). No difference. It gets harder to start each time and sounds like a tractor when it dies. At first thought this was a fuel issue, but I think I've ruled that out. Plugs are clean, as is oil. Temp is 165-170 after a 2-3 minutes. Oil pressure is steady 70 psi at 2200 rpms.

Went out and tried again yesterday. Started right up and ran for about 3 minutes, then died again. Here's what has me vexxed about it. My whole shop smelled like a chemical factory fire, as my header paint was being completely torched off (smells worse than plastic burning and still stinks badly the next day). Strangely, it wasn't burning up close to the heads, but down almost to the collectors. Timing is still about 28 degrees +/- at 2200 rpms (which is where I need rpm to stay while breaking in this new flat tappet cammed motor) so this makes no sense. I do have vacuum advance connected now. I've tried it both ways, on and off, but since I'm timing it at 2200 rpms, I don't think it matters. Or does it? Sprayed 1/2 can of carb cleaner through it, just to see what that might do. That didn't kill it, but it died about 45 seconds later. I'm setting rpms by turning in the idle screw and then varying it (on the few times it's stayed running for more than 2 minutes). Initially, it starts up fine and seems to run well in the beginning, but gradually, it starts to sound like a tractor, like its binding up or the timing is all wrong, and becomes more difficult to start. I was methodical about installing cam and timing set but it sounds like timing is off. I was also very careful to ensure plenty of end ring gap when I installed the new Hypereutectic pistons. At a complete loss with the header paint going up in flames. That's a sign that fuel is burning late, in the headers. How is that happening? Hopefully this dings a bell in somebody's head. Just trying to get the motor broke in, so this is NOT the time to be dealing with all this starting and stopping 15 times. I'm at the end of my rope here...

 

I think you should do a compression test, I fear the worst. Next would be to pull the valve covers and look for good movement on all the rockers while turning it over.
There are other possibllities i.e. sheared dizzy pin, lack of fuel etc.

Good luck.

 

I just went through the entire valvetrain again, added hardened pushrods and adjusted lash. Pulled lifters and they look perfect, light even wear and spin freely in bores. Also put in new coil and battery and found a better ground for the e-choke. It's got ridiculous compression... What does that mean, you "fear the worst"?

 

Helloooo??? Anyone?

 

Fearing the worst in this situation probably means fearing you have cam/lifter damage.

Since the lifters look good you are probably ok so far.

Timing at higher rpm--doesn't the distributor have a centrifugal advance?

Fuel? Sounds like it's running out. Some obstruction in the system? Is there gas in the carb when it dies?

 

Hopefully you have this sorted out by now. But it sounds exactly like the float level or levels are way too high or a needle and seat isn't holding. When either of those things happen, it will start dumping fuel out of the boosters and flood out. This doesn't happen instantly it takes a couple of minutes. Disable the choke not needed on run in and look in the carb when it's first started. An engine not under a load is only going to be running on the idle and transition circuits at 2000-2500 rpm. You really need to be up around 40-degree advance running with no load at 2000 rpm.

 

Dirty fuel line... the one thing that was not new. Ended up running a fuel line to a 5 gallon container and that's how I isolated the issue. Set base timing to 7 degrees, ran ported vacuum to dizzie, started, ran and broke in cam w/out issue. Drove on the highway for the 1st time today. Good runner. The thing that was most disappointing is the "2000 degree Flame-Proof" paint is 60% torched. Would not recommend.

The lesson here is don't make things more complicated than they are... note to self.

 

There is no such thing as flame proof paint that comes in a spray can.

The basics are often over looked or assumed to be ok. You are not alone in making things more complex that it really is.

 

Why set the timing to 7?