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RE: Double pumper and funny clearances

To: Theo Smit <TSmit@novatel.ca>
Subject: RE: Double pumper and funny clearances
From: Tom Hall <modtiger@engravers.com>
Date: Wed, 26 May 1999 20:56:56 -0700
At 03:33 PM 5/26/99 -0600, you wrote:
>Dick, and Listers,
>I guess I wasn't being specific enough in my post (and I have a question about
>yours): My fitment problem is (was) only in the fore and aft direction, not up
>and down. I was trying to establish what the constraining measurements were,
>i.e. what is the correct length of the front pulley (I finally got a partial
>answer this morning from Tim Ronak), and what are the correct engine mounts. I
>have two identical engine mounts, which everyone agrees is not right. With the
>double pumper in the car, on the F4B manifold, and a 1/4" carb spacer/gasket
>combo between the carb and manifold, and the original AC air cleaner, the
>face of the crank pulley (Not the fan, or the water pump pulley) will rub the
>rear side of the rack tube under certain loading conditions, with about 1/8"
>clearance or so present with the engine off. The carburetor occasionally
>the firewall right where the Holley lettering is on the rear float cover
>the float pivot bulge in the cover), and it rubs the stiffening rib on the
>I modified the engine mount holes so as to sit the engine farther back (by 
>3/8"), and in doing so, caused the carb to hit the firewall in a very positive
>way, i.e. there was no way I would be able to make things fit unless I cut the
>stiffening rib out, or changed the carburetor, so I chose the latter since
>that's a less permanent alteration.
>So my question to you is, is the stiffening rib on your Tiger removed for carb
>clearance? How many Listers out there have a Tiger with an F4B/Double Pumper
>configuration without having the rib cut out, and how much clearance is there
>between the carb and firewall, and between the front pulley and the rack?
>I can accept that my car has either some covered-up frame damage (it would
>to be pretty well hidden), or else that it has a case of small tolerances all
>around, but I would like to know what others have for clearances before I 
>make a
>judgment on that.

The dimensional discriptions you have given for your firewall and carb
clearances do not sound typical.  The notching of the firewall angle brace
was done on very early competition Tigers because of the "LeMans" float
bowls which preceded the current center pivot design which is still used on
Holley carbs.  I know many center pivot vacuum secondary and double pumper
installations which do not hit the firewall.  The longest configuration has
the double jet blocks and centerpivot bowls.  I am speaking of normal size
4 bbls 500 to 750 or so cfm rated not a dominator or 1000+ cfm carb.
Typical pully to  rack clearances will allow you to pass the belt through
this gap.  

I would be inclined to check your as-is structural dimensions against
another Tiger.  It sounds like someone has moved the rack mounting to the
rear, the engine back, or you have some frame damage /modification that is
causing your reduced dimensions.  I have seen frame damaged cars that would
/ could emulate your problems.  The other possibility is that your Tiger
has been "clipped" and the dimensions have been altered by a careless
repair person.  This kind of analysis is tough to do with the car assembled. 


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