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MG MGB Technical - need heatshield ideas

I have read through all the Archives on vapor lock ... which I've deducted must be my basic problem... to realize that I don't have any heatshielding on my '78 B with a Weber DGV carb !!!! I find myself having to crank the engine over and over and pump the accelerator pedal to get the engine to start after it's warmed up and has been stopped for more than 3-5 minutes. The carb is new from 2003 with new fuel lines-filter-tank and in-tank filter and has always done this. I tried rerouting the fuel line through the openings on the left fender well - away from above the exhaust manifold - without any success (actually made things worse). BTW, the coil is relatively new.
So my question is: can anyone provide me with a design for a heatshield...from what material...how to attach the shield, etc. Maybe someone could provide pics. of a Weber and the heatshield at various angles. I do not have any of the original intake-exhaust and old ZS carb stuff or shield that may have been on in the past. A previous Weber DGV on a Cannon header set-up was on the car when I bought it. Thanks for any advice.
Richard
R.M. Standish

Hi Richard.

It is my belief that there really isn't sufficient airflow under the bonnet of a B, and that sorting this would help with pinking, running on, overheating and vapour lock probs.

Has anyone investigated this ?.

Don
Don

Don,
When I restored the car I was very particular to replace the (missing) Mud Shield that fits between the rad. and engine block. I had been told that without it the air coming in from the front of the moving car will slip under the engine and reduce the already poor 'ventilation' in the engine bay. However, many comments on the essential need for a Heatshield under or between exhaust and carb are the incentive to get one on my car and hope for some improvement. Granted the design flaws of the engine compartment will not be aleviate. That's not my objective.
Richard
R.M. Standish


R.M.,

I fabricated a three piece heatshield for my A from some aluminum stock (slightly less then 1/8 inch). This stock is inexpensive from a steelyard supply and very easy to cut,grind and bend or hammer to your required shape. I first cardboard templated what I needed then transferred to the stock and formed it. Then I riveted header heat shielding to it's hot exhaust side and mounted it. This was on a maniflow intake and header combination so a stock shield would not work. It passes the put "put my hand in there while everything is very hot" test with flying colors. Being three piece it is very easy to take off for access as needed.

The fuel line can be heat "slipcovered" very easily also, see the Summit catalog.

I got the header heat shielding from Summit racing for a few dollars and the stock was probably about that too.

It's not as hard as it first sounds, jump in!

Good luck

Tom
Tom M

Richard, you have mail. Just a simple shield design.
Hope this helps.
Bill Young

These are good ideas,thanks.
I looked at the pic Tom has sent to me via e-mail. I wonder if the owner of the car (with a Weber and Peco header)has had the same problems, since there is no shield under the carb either.!! Anyway, I can see what needs to be done.
It would be nice to hear from someone that has one installed and know exactly where to attach the shield. Appreciate the help.
Richard
R.M. Standish

Richard. I run a Peco and Weber combination on one car and a Cannon and Weber combination on a second car. Both daily drivers. I have not had the problems you describe in something over five years of use on both cars. This includes summer time driving in Arizona in ambient air temperatures of over 110 deg F. Hence, I am not sure a heat shield will correct your problem. By the way, one car is running a Facet fuel pump and the other a new SU fuel pump. You may wish to check out your pump if the heat shield does not work. David DuBois wrote a good article on them, including current volume and pressure specifications. You can see it at www.custompistols.com/ under the MG and articles section. Les
Les Bengtson

Hi Les. Thank for the comments. I've left you mail for you.
Richard
R.M. Standish

Richard. Have not received any mail. If you sent something, please send it again. Thanks, Les
Les Bengtson

This thread was discussed between 26/08/2004 and 29/08/2004

MG MGB Technical index

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