Bob D/airflow Q?

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GTS225

Post subject: Bob D/airflow Q?

PostPosted: Tue Aug 06, 2002 11:10 am

Bob, (or anyone), I'm looking at fabbing a 90* adapter to bolt to my EFI-converted manifold, for throttle body mounting, and am looking for tech opinions concerning a couple options.

I have the flat aluminum plate I need, and have found a 90*, cast alum fitting from McMaster-Carr that will work. My problem is that the dimensions don't quite match the throttle body.

If you would, please take a look at item no's 43485K125, & 43485K126 on the McM-Carr website. There's a search available on the home page that then links to tech drawings of the part(s) in question. The bore of my throttle body measures 2 9/32".

My worry is that I may suffer a reduction in vac with the larger fitting, but will have a greater airflow capability. OTOH, I'm concerned that the smaller one will be a restriction, as well as causing excessive turbulence in the throat. Bear in mind my future plans to turbo or supercharge the engine.

I'm leaning toward the larger of the two, FWIW.

Roger

McMaster-Carr Supply Company
GTS225@aol.com

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Bob D

Post subject: Re: Bob D/airflow Q?

PostPosted: Tue Aug 06, 2002 6:17 pm

Quote:

: Bob, (or anyone), I'm looking at fabbing a 90*
: adapter to bolt to my EFI-converted
: manifold, for throttle body mounting, and am
: looking for tech opinions concerning a
: couple options.
:
: I have the flat aluminum plate I need, and have
: found a 90*, cast alum fitting from
: McMaster-Carr that will work. My problem is
: that the dimensions don't quite match the
: throttle body.
:
: If you would, please take a look at item no's
: 43485K125, & 43485K126 on the McM-Carr
: website. There's a search available on the
: home page that then links to tech drawings
: of the part(s) in question. The bore of my
: throttle body measures 2 9/32".
:
: My worry is that I may suffer a reduction in
: vac with the larger fitting, but will have a
: greater airflow capability. OTOH, I'm
: concerned that the smaller one will be a
: restriction, as well as causing excessive
: turbulence in the throat. Bear in mind my
: future plans to turbo or supercharge the
: engine.
: I'm leaning toward the larger of the two, FWIW.
: Roger

Roger,

I think that I would also go with the larger one. I don't think you will have a vacuum problem with only about 3/16" difference in the ID.

A short time ago someone posted a picture of a side draft manifold for a SL6 either here or on slantsix.com. As I recall it was for dual Webber carburetors and was made in Australia. I wonder if there is some way that you could use that. It would require an adaptor to use a single throttle body. I tried the search function with no luck. Maybe someone else will remember the details.

Bob D

BBobbias@aol.com