A friend of mine just installed a 383 Golen long block motor in his Chevelle, and at idle the header primarys 3,5 and 2,6 are glowing bright red, while the other primarys remain normal.

What would cause this?

383 c.i.
AFR 195 heads
Single plane intake
Demon 750 carb
Hyd. lifters
Hooker super comp headers

Sorry thats all I know about the motor.

 

Perhaps running lean in those cylinders. Also a slight chance the timing chain is off the tooth. Does the engine idle/rev normally?

 

Runs and revs fine, idle is smooth.

It's a single plane carb setup, so I don't see how 2 out of the 4 primarys on each side would run so lean, while the others get the right mix.

I was thinking, perhaps the rockers on those 4 cylinders were severely over tightened, causing the exhaust valves to hang open even at idle. Never had a chance to check them though, I only saw the car running for a few minutes before I had to go.

Just thought I would probe the hive mind before I went back over to tinker with it.

 

Maladjusted valves are a very good possibility.

 

Thats was the first thing that came to mind when I saw it, but I really dont know all that much about motors... just enough to get my *** in trouble.

 

are you sure you got the wires on in the right order? Ive seen that exact thing on a TPI motor that had a couple crossed wires. even with the crossed wires it ran smooth. I would check that first since thats the easiest.

 

It's actually a *rich* condition that will cause the primaries to glow because the unburned fuel will actually ignite in the primaries.

As others have said, mis-adjusted valves can cause this as well. An exhaust valve that isn't closing all the way will allow unburned fuel to enter the primaries and ignite, causing the red glow.

 

but would the car still idle and rev smooth

 

My first thought would be no, but its amazing the difference a load will cause on an engine. Just because it revs smooth doesn't mean it will as soon as it gets a load.

Check the valves and wires first.

 

False. A rich condition means there is not enough oxygen in the combustion process to burn the fuel and will not burn even on its way out of the cylinder head. A lean condition means the combustion process is oxygen rich and will burn much hotter in the combustion chamber which equates to hotter exhaust. Do some research.

 

I had a very similar problem with my car. The primaries were red at idle and the richer I made the tune, the more bright red they turned; leaning the tune out *helped* the problem.

As I stated, a mis adjusted rocker can cause the same condition as unburned fuel gets into the header primaries. The problem is compounded with a large cam where you typically have a richer idle setting due to the overlap of the cam, but you apparently knew that.

 

Both rich and lean will make them glow.

 

cats?

 

to much fuel in the exhaust..most likely, the cause is the timing ...sounds like its retarded to much