Re: IML: Manifold Leak 64 413

[David Whitney <hazegreen66@xxxxxxxxx>]

Let's get this right -- the INTAKE manifold was white from heat?

 

What's your vacuum reading at idle?  What's your initial spark advance?  What kind of fuel are you using?

 

Excessive heat in the combustion chambers is generally caused by running lean, not enough spark advance and/or octane too low for your engine.  An intake manifold leak would contribute to a lean condition in one or more adjacent cylinders.

 

The other thing to look at is your spark plug heat range, but check that by reading a set of new plugs after you have addressed the other possibilities.

 

Lastly, and least likely, your valve timing is off far enough that the intake valve is partially open during combustion, allowing the burning mixture to expand into the intake.

 

How are your exhaust manifolds doing?  Glowing red?  Next time you remove them (ha ha ha) you may find that the surface where they mate to the heads is rough and pitted from excess heat.  This can also be checked by a shop that will measure your exhaust gas temps and use infrared to detect hot spots under the hood.

 

Happy motoring,

David

'91 K-Imperial driver
'66 Crown Coupe project
'66 LeBaron dual air and every option known to man

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