[Roadsters] Intake manifold question

[Gary and Cindy Ault]

Oliver,

If the plugged holes are about halfway between the carbsand the head, and 
about 3/8 NPT, they're called "balance tube plugs".  Not sure what the 
original purpose was (because they are shown on early manifolds), but they 
were later adapted for use as the inlets for the anti-backfire portion of 
the Nissan Air Injection System. high vacuum allowing fresh air into the 
intake, diluting the incoming air/fuel mixture and preventing the backfire.

Those holes do not need to be connected with a hose, since they're already 
part of the balance tube between the carbs.

Gary

----- Original Message ----- 
From: "oliver" <sumton at sbcglobal.net>
To: "Datsun" <datsun-roadsters at autox.team.net>
Sent: Tuesday, August 23, 2011 11:36 AM
Subject: Re: [Roadsters] Intake manifold question


> no, these are just the engine side of the carbs.
>
> if you look at this picture  http://tinyurl.com/3l3hpyt
>
> the little bolt head is very evident on the left (front) manifold halfway 
> between the head and the carb.
>
> apparently this opening is supposed to be connected via hose to the 
> right/rear manifold for balance
>
> --------------------------------------------------
> From: "John F Sandhoff" <sandhoff at csus.edu>
> Sent: Tuesday, August 23, 2011 11:31 AM
> To: "oliver" <sumton at sbcglobal.net>
> Cc: <datsun-roadsters at autox.team.net>
> Subject: Re: Intake manifold question
>
>>
>>> My intake manifold (early 67 roadster) has matched holes on each
>>> side which are filled in by a bolt..
>>>
>>> I just saw another manifold which has what I am assuming to be a hose
>>> assembly which apparently acts as a kind of balancer between the two.
>>
>> Are these threaded fittings on top of the runners? Sure sounds like the
>> fittings for the smog pump plumbing, which would indicate that your
>> car experienced a manifold swap somewhere along the way...
>>
>> -- John
>>     John F Sandhoff   sandhoff at csus.edu   Sacramento, CA
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