blocked crossovers

[gene]

The main reason I have seen to block the crossovers is that eventually
this heat in the intake manifold breaks the manifold. This is such a
problem that almost all of the original manifolds have to be repaired by
welding and re-grinding the manifolds. Mine developed a crack in the web
between the throats. Then exhaust gases leak into the intake manifold.

This crossover was engineered in the intake manifold to preheat the gasses
and possibly in the very cold climates this is not needed.

gene

>
>-----Original Message-----
>From: Gcbr
>To: gmcmotorhome
>Date: Friday, October 08, 1999 6:12 PM
>Subject: Re: GMC: We are in
>
>
>>In a message dated 10/8/99 6:56:44 PM Central Daylight Time,

>>
>Going to block off the crossovers on the manifold.
>
>Arch,
>
>I hope I don't start something here but I am curious. Why do you want to
>block the crossovers on the manifold and how will you do it? Is it to try
>to make it run cooler or??
>
>Bob Schoner
>Still looking for the perfect GMC
>
>
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
http://www.california.com/~eagle/

 

[steven d. ferguson]

The main reason I have seen to block the crossovers is that eventually
this heat in the intake manifold breaks the manifold.
I've seen a ton of these at swap meets & on engines I've torn down.
I'm not quite sure it is caused by blocked crossover passages as many of
the ones I've personally seen were open. The web between the throats in
the manifold is quite thin, actually, a pretty poor design. GM
corrected this by reinforcing this area in later years. The Olds
manifold web looks pretty thick in this area.
Steve Ferguson
San Diego