Are Your Curtains (Drapes) Closed?
(Thanks to John Mackenzie of the South African MG Club for this heading).
Does your MGA run hot? That’s like asking, “Does the Pope wear a big hat?” Maybe you have a new repro grill fitted to your MGA.
These new grills are different in shape from the original grills. In this article we try to make a comparison of the two slatted pieces. The two grills have the same number of vertical slats – 28 on each.
The first thing you notice is the difference in weight – the repro grill weighs about 1 lb 4 oz (600 grams), while the original grill weighs about 2 lbs 4 oz (1000 grams). Most of the weight difference is contributed by the upper and lower rails – on the repro grill these are aluminum (aluminium), while those of the original grill are made of steel. But the vertical slats on the original are polished stainless steel, while the slats on the repro grill are chromed on brass. This also contributes to making the original heavier.
The most significant difference is in the shape of the vertical slats. On the original grill, the slats measure ½” (12.7mm) overall width. On the repro grill they are a 1/16” (1.2mm) wider.
The width difference can be clearly seen in the photos here, but there is an explanation why they look different. On the original slats, the leading edge has been formed so that it is bent at 110 degrees, i.e. tucked in slightly. On the repro grill, the leading edge is only 90 degrees, thereby presenting a larger surface to the incoming air.
The last difference that can be seen is the angle of orientation of the slats. On the original grill, the slats are “turned” significantly more than on the repro grill. This results in a larger gap between the slats – about 5/16ths of an inch (8mm) on average, compared to 7/32nds of an inch (5.6mm) on the repro grill.
This difference alone, if my calculations are correct, gives a whopping 40% increase in flow area to the original grill over 28 gaps. Hence the fact that “the curtains are closed” on the repro grills. This can most clearly be seen if you compare the views of the back of the grills.
Original Grill From the RearRepro Grill From the Rear
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Comment by: Fred Woller
Thanks for getting back to me so quickly. I will try it very slowly .A new grill is a good idea and have heard a lot of positive comments, but its a lot of money at this time. Thanks again
Comment by: David Quinn
Fred, its been a long time since I did mine but as best I can recall, for the most part I turned them one at a time by hand, at least for the first pass through. If I used pliers, I would think wider ones would work best and just doing minor twists at both ends. I never turned them with enough force that it effected the rivets in any way.
Since making my original post back in 2015, I purchased a new grill from Scarborough Faire, Inc. Its built right and there is no need to do any adjustments.
Comment by: Fred Woller
Has anyone designed any special tool to turn the slats on the reproduction grill ? Or do we just use needle nose pliers wrapped in a towel. Do the attaching rivets stay in place or get loose?
Comment by: David Quinn
Even with an original grill I’ve always turned each slat to insure more air intake.
Comment by: David & Rita Houser
Very interesting article and I daresay it would be wise to check the T-Series and MGB early cars as well.
Comment by: Robert D. Peate
Great article, so true. Cooling became an issue and had to remove my repro grille. I have since replaced the grill veins with a stainless 1/4 inch wire mesh. Looks great and keeps the engine cool.
Thank you,
Bob
60 Black MGA owned since 1980.
Comment by: John Melton
Is this true of ALL repro grills?
It’s been about 2 years and no more covid lockdown. MGA has been running great, except heater valve started leaking ,which started another set problems-but thats a story for another day. About the repro grills , i have had one for 40 years and finally ,after reading the above info. I decided to open the angle of the blades . I took 2 needlnose plyers and 2 thick pieces of towel , and easily turned the blades open with the plyers at upper and lower of each blade at the same time. No scratches to the grill and i now have openings equal to the original grill. I start at the center first and then move outward. It’s easy to see the difference from a few feet away and will certainly make a difference. As an added benifit , its now easier to use chrome polish on the blades without scraping my fingers or nails .