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Bill,
If you have the catalyst sitting directly under the carburetor
on your MGB I assume that you have a '76 or later B with the
combined intake/exhaust manifold.  Unless you need the cat to pass
emissions, you should try to find a used intake and exhaust manifold
from an earlier B and replace the carbs with a pair of HS4s.
The earlier cast iron exhaust manifold has dynamics similar to a long
center branch header and will give you a considerable improvement in
low speed torque.
If you absolutely must have a cat in the system, get an aftermarket one
from J.C. Whitney and splice it in in front of the front muffler.
Peter Schauss
Long Island, NY
1980 MGB
1963 BJ7
-----Original Message-----
From: shop-talk-owner@autox.team.net
[mailto:shop-talk-owner@autox.team.net]On Behalf Of Bill Gilroy
Sent: Tuesday, June 04, 2002 10:43 PM
To: shoptalk
Subject: Re: Under the hood temperature
Hello Bill,
Monday, June 03, 2002, 10:49:11 PM, you wrote:
There have been several questions why?  This is what is happening.
When the temperature outside is > than 75F I have the following
problems:
         1.  When the car is idling at a traffic light after about 1.5
         to 2 minutes it starts to run rough, stumble and miss.  This
         continues while I pull away for about 1 minute at speed when
         everything goes back to normal.
         2.  If I shut off the car and try to restart it in about 5
         minutes I have the same problem as in 1.
While this might not be "vapor lock", (correct if I am using the term
incorrectly) it is heat related.  I have not had this problem all
spring when it was cooler.
I am going to insulate the fuel lines tomorrow, I really can't move
them any further from the exhaust manifold.  I would like to see what
the under hood temperature is and when the problems start.
I am going to go with the radio shack thermocouple and a DMM.  My
meter does not do temperatures, but I can just read the voltage and
convert.  Simple, easy and cheap.  I will let the list know what I
find.
-- 
Best regards,
 Bill                            mailto:w.gilroy@verizon.net
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