The Heat Shield

[John Coffey]

Well... it started out simple enough.

Ya see, at the first few autocrosses of 2000 I was having a problem where the car would load up (run really rich) in grid and I would get a miss during the first 100 yards of the run. Then the car would clear out and run great. Some sleuthing by me and Bryan Lampe determined that my stock heat shield was not enough to keep fuel from boiling in the float bowls on the rear carb.

So... I decided to build myself a new heat shield. Sounded like a simple enough project. Little did I know.

I called Erik at EMI Racing to see if he might have one lying around.

He said, "No, but I bet you can build one out of a titanium/aluminum/ceramic honeycomb that would be great." I said, "Huh?" He said, "Call Cherry Metals in Long Beach, talk to Mark and see if they have any titanium scrap lying around."

I did and they did. $75 later I had a 4' x 4' sheet of 30 year old titanium/aluminum/ceramic honeycomb. Actually, Bryan Lampe had it 'cuz he works in Long Beach and I couldn't get to Cherry Metals before they closed. Bryan was kind enough to drop it off at Erik's shop.

I called Erik the next day and said, "I'll come by tonight, get the sheet, and build it at home this weekend." Erik replied, "How are you going to cut it and bend it?" I replied, "With a hacksaw, vice, and body hammers." After Erik stopped laughing he said, "You can't saw it since its a honeycomb sandwich and you can't bend it with a vice and hammers 'cuz its titanium. Just come by the shop and we can use the table saw with a grinding wheel and my big sheet metal break." Great...

It took two weeks until our schedules worked out.

I drove the Z down to Erik's shop on a Saturday afternoon (we were supposed to meet Saturday morning but he worked until 6am that morning). Erik has the Grand Am GTO Viper on the lift. He's pulling body molds off it for a carbon fiber roof and he's moving the engine back 6" and down 4" in the chassis. Little stuff.

I proceed to pull the stock heat shield off the Z and make a cardboard template for the new one, all the while trying to stay out of the way of Erik and "Stan the Carbon Fiber Man."

After I have the template done I ask Erik where the table saw is. He points to a 10' pile in the corner of his shop. Great...

I spend the next 1/2 hour digging it out.

I ask Erik where the grinding wheels are for it. He says, "Home Depot. And buy yourself a class A breather when you're there." I ask why. Erik replied, "Because titanium dust is toxic, worse than asbestos." Great...

After I get back from Home Deport (the first of 3 trips) I setup the table saw outside, behind the shop. Once everything is ready Erik comes out to supervise. He mentions, "Be careful not to get the metal too hot when you're cutting it. If the titanium ignites there's no way to put it out. Just look for bright white spots. If you see that, stop cutting and get ready to throw it to the ground." Great...

So, I spend the next hour very carefully cutting the titanium/aluminum/ceramic honeycomb. I only saw one white spot and I was ready to toss it, but the spot turned orange, then red, and then back to gray.

Now I get to drill some holes. I was ready for some very involved procedure and asked Erik what I needed to do. He replied, in a somewhat condescending manner, "Get the drill and use one of those carbide bits on the tool box." Drilling holes was pretty easy.

After the holes were drilled, Erik's wife called and gave him the basic "get home and pay attention to me or you're a dead man" ultimatum so I had to stop work and get going. Unfortunately, to the detriment of my speedometer cable, I forgot to put the stock heat shield back on when I drove home from Erik's shop. Pretty amazing how quickly a set of headers burns through the rubber cable covering.

It was another two weeks before Erik and I could get our schedules together.

Sunday, I've got the aerospace heat shield cut out and ready to bend. Erik drags out this 6' sheet metal break and it takes both of us pulling hard to get the first bend in. We go to check it on the car and realize that we have to pull the carbs. So, I spend 1/2 hour getting the carbs off, and destroy the carb gaskets in the process. A call to Pep Boys, AutoZone, Chief, etc. yields nothing. So I go to Pep Boys and buy some gasket material and spend the next hour making 4 carb gaskets.

Erik and I checked the heat shield on the car and, over the next 1/2 hour, make the necessary bends/adjustments to get it to fit. The heat shield is ready to install but its looking pretty old and aerospacy (don't want to draw too much attention to it, even though its a legal modification). So I run to Pep Boys and get some flat black header paint and make it "invisible."

We get it and the carbs all installed, but the car is running funny. So, we tuned and rebalanced the carbs and everything runs great. The best part, with the engine at 200+ degrees you can use your bare hands to adjust the carbs!

All this for about $100 in materials, a speedometer cable ($80), 4 grinding wheels ($20), a class A breather ($40), 1 drill bit ($5), and 6 hours of highly toxic and flammable work over a month! FYI... Early on I had the seemingly brilliant idea of making a bunch of these and selling them. NFW!

But I've now got the best damn heat shield on any Z in the world! Of course you can adjust the carbs bare handed on Bryan Lampe's Z with his $10 aluminum heat shield... Great...

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John Coffey

johncof@veriomail.com

[Mike]

Originally posted by John Coffey:

But I've now got the best damn heat shield on any Z in the world! Of course you can adjust the carbs bare handed on Bryan Lampe's Z with his $10 aluminum heat shield... Great...

Niiiiiice. But, hey. Yours is TITANIUM!!

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Mike Gholson

1971 240z, Mikuni Carbs, Tokico 5-way Adjustable Struts, Ferarri Yellow, Stock Engine, 15x9 wheels w/50 series Falken tires, Currently being restored.