Re: IML: Big Block Red Hot Manifolds

[Christopher H <imperial67@xxxxxxxxxxxxx>]

Mike,

I tend to think a defective or clogged catalyst is behind this, but that
usually accompanies a car being way down on power. Does your car have a cat?

Coolant temperature is not likely the cause. Your coolant won't get much
hotter than 250F, whereas your combustion occurs at 2,400F or so. And I'd
think super-lean running would not be smooth at idle.

Check downstream first... And start with the cat. Let us know, please!

Chris in LA
78 NYB Salon (400 w/cat)


On 6/28/05 8:57 PM, Mike Pittinaro at mechimike@xxxxxxxxx wrote:

> Anyone care to lend a helping word of advice on what
> could cause both manifolds on a 1978 400 cu in big
> block to glow red?
> 
> Timing is set to the spec, new t-stat, new fan clutch,
> radiator flows OK, belts/hoses OK and lower rad hose
> has the internal spring.  New plugs and wires.  Engine
> reverse flushed and new coolant installed.  New vacuum
> lines and stoppers.  Engine has a thermoquad
> carburetor.  
> 
> My own thoughts are a cracked base of the carb, or
> possibly a leaking intake manifold, something that
> would cause a lean-running situation.  Engine seems to
> idle OK though, and has decent power.
> 
> --Mike Pittinaro




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