MGC Forum

Heat shield for 3 carbs

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ron neal Avatar
Coastal, SC, USA   USA
1962 MG MGA MkII
1968 MG MGC
1969 MG MGC
1969 MG MGC    & more
I had someone enquire about a SS heat shield for the 3 SU HS6 set up using headers and the Maniflow intakes.
Does any one have a template or does anyone manufacture these for the above application. I am pretty sure this was discussed some month ago but I cant seem to recall the end results.

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Ken Plumstead Avatar
Smithers, BC, Canada   CAN
1965 MG MGB
1968 MG MGC GT
Hi Ron,

I've been saving pics of various triple SU set ups and there are a few with custom heat shields. Attached below one for the Maniflow manifolds and one for the Herbold ones.


MG: Transforming gasoline into Fun!!!

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bills Avatar
bills Bill Spohn
W. Vancouver, , BC, Canada   CAN
I found that I didn't need to use a heat shield despite using tubular headers, which radiate more heat. The distance between the headers and the float bowls was sufficient. Had one of the floats been too close, I would have just attached a single carb bowl heat shield using the cap nuts.

Bill Spohn
Current: 1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1957 Jamaican MGA (200 bhp)1965 1971 Jensen Interceptor (350 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
2007 BMW Z4M coupe (340 bhp)
Recent: 1969 MGC roadster (175 bhp),Jensen CV8 (375 bhp),
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
North Vancouver BC

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yellercat B R
Little Rock, AR, USA   USA
From cardboard form

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PFT-000 Bruce Ibbotson
Brisbane, Australia   AUS
1968 MG MGC GT "The Truck"
1968 MG MGC GT "The Truck"
Hear shields are dependent on where you live and your climate.

Downton did not even supply the 1/2" thick Black Insulator blocks normally used on the MGC and no heat shielding at all, clearance for the front SU air cleaner to the Bonnet (Hood) was the reason the insulator blocks were not used.

Herbold or Maniflow inlets are horizontal and this problem does not exist. I fitted the Kit 45 and in our Sub Tropical & Humid climate the car would not idle in traffic in Summer. Too much under bonnet heat for the SU's to handle.

I had to make my own heat shield which comprised 2 sheets of 22 guage aliminium alloy with 3/8" spacers between the sheets, the front section angled towards the fan so air could flow between the sheets at idle.
I removed the tack welded on plate that was in front of the factory air cleaner to get cooler air into the carbs when moving.

The current set up has an aliminium/ceramic/aliminium heat shield sheet between the original aliminium sheets. I have the car set to idle at 700 rpm now with air -con on or off [the vacuum motor on # 1 throttle shaft] and the car is a pleasure to drive in Summer even in stop/go slow crawling traffic.

So to sum up it depends on how and where you use your car, the Downton system must be OK in the UK where the very few Downton Stage 3 cars live. I think I have the only Stage 3 car outside of the UK.


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Truck photos 28 MAR 14. SU heatshield 004.jpg    47.6 KB
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MGC2912-6317 Michael Price
Ottawa, Canada   CAN
I believe the diagram for the Maniflow heat shield posted by Ken Plumstead shows incorrect dimensions with regard to the centres. It shows centres of 21 cm. I bolted my Maniflows to a spare stock intake manifold, so that the head ends were together. This should give the correct carb spacing at the carb end of the Maniflows. I then measured centres of 20 cm. This also puts out some of the other dimensions. Apart from that it seems like a good design and I plan to use it with suitable corrections.


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