engine and drivetrain Are heat shields necessary?

[Emyers]

Bud,

In my case the switch came after ditching the smog stuff back in the seventies. That and the vacuum operated secondary that never seemed to work right without the maze of vacuum lines, dashpots and relays. Even then there was not much in the way of support for the Solex on the aftermarket had that been an area of interest. Still drive the same 02 that I bought in 74, and the downdraft Weber is supported very nicely.

Earl

[osbourne]

Bud,

In my case the switch came after ditching the smog stuff back in the seventies. That and the vacuum operated secondary that never seemed to work right without the maze of vacuum lines, dashpots and relays. Even then there was not much in the way of support for the Solex on the aftermarket had that been an area of interest. Still drive the same 02 that I bought in 74, and the downdraft Weber is supported very nicely.

Earl

Interesting. I'll have to find one of those Solexes to check out. Solex parts, at least for those used on the various Porsche and VW models, have not been difficult to find. However, I can see how an emission type unit, fitted to a limited number of new cars "back in the day" might be a bit of a challenge to find parts for. Vacuum operated secondary, you say? Interesting, I can see why most of us (possibly me included) would run the other way.

Thanks, Earl.

[Guest Anonymous]

Just curious. Saw nothing specific in the archives. Never in my muscle car days have I ever seen heatshields on exhaust. Just headers, plug wires right next to them, and everyone is running fine. I am into the 02s now and it seems everyone has heat shields. just curious if there is an 02 specific reason to use them? i know it evacuates some heat from the engine bay but not that much. plus if you run a cold air induction setup (alos rare i see on 02s) then you don't have to worry about the heated air being taken in in the first place.

please give me some feedback on this if you can

Muscle car days? What muscle cars are you referring to? Your question suggests you are better suited for muscle cars or the other way around than an 02. Why your experience with muscle cars or Holley four barrels or muscle car drives shafts and spark plugs should automatically translates to all cars, or 2002's, in general, is . . . curious.

Plenty of muscle cars had heat shields. I am staring at one for a 1970 Cuda (drivers side). I am certain I have seen heat shields on Fords 428 CJ engine (part no 9A603). Ever heard of header wrap? It acts as a heat shield too and has been around since exhaust manifolds first got hot. Besides, not all muscle cars were the same any more than the design of a U.S. made car should be the same as European or Japanese cars.

If you had access to or referred to a shop manual and realoem, the answers to most of your questions would be obvious.

You asked if the heat shield was necessary - not whether it was a good addition. You never describe exactly what you think is a heat shield.

Many 02's had a metal shroud that partially covered the exhaust manifold. On many models the primary purpose was to create a means of preheating intake air. The ducting to the air filter housing is a dead giveaway. One piece of this shrouding is described as a "protective cover" (pn 11631262146)

If you are referring to an extended exhaust manifold gasket that protrudes upward beyond the manifold, that does serve as a heat shield (pn. 11621723876). However, it was never standard issue for 02's and did not become standard issue until the e30 models or possibly later E21's. The original 02 did not have the so-called gasket heat shield and there are plenty of them on the road operating fine [without them. I have two of them.

You state: "i know it evacuates some heat from the engine bay but not that much." Now its sounds like you are describing duct work similar to that found near brakes or radiator exhaust vents. Neither the extended gasket heat shield or the metal shrouding around the exhaust manifold - "ducts," "vents,"or "evacuates" the heat from the engine bay. It may isolate heat or provide a limited barrier for the heat but evacuating it from the engine bay does not make sense. In fact the design of the metal shrouding still convects quite a bit of heat although by providing much more surface area it dissipates it more like a heat sink.

Exhaust wrap may cause better retention of the hot exhaust within the exhaust system and by virtue of this fact may reduce engine bay temperatures operating. Since you did not refer to wrap in your post it is unlikely this is what you meant. Going back to the extended exhaust manifold gasket, I don't see how it promotes heat evacuation from the engine bay. Rather, as Esty was quick to note, it isolates the heat and serves as a limited barrier between the the plug wires and much of the heat radiating from the manifold.

[Guest Anonymous]

Never in my muscle car days have I ever seen heatshields on exhaust. please give me some feedback on this if you can

Come to think about it, many STOCK muscle cars were equipped with exhaust manifold heat shields. I gave you two examples in my earlier response. A quick search reveals that these were on the early 70's corvettes http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=400070448241&crlp=1_263602_263622&ff4=263602_263622&viewitem=&guid=e82efb701250a0e204e73c87f9060dfa&rvr_id=&ua=WXI6&itemid=400070448241 Same was true for GTO's and 442's.

As far as I can tell, these devices "shielded" various components from heat but they did not evacuate heat from engine bay.

[Guest Anonymous]

Never in my muscle car days have I ever seen heatshields on exhaust. please give me some feedback on this if you can

Come to think about it, many STOCK muscle cars were equipped with exhaust manifold heat shields. I gave you two examples in my earlier response. A quick search reveals that these were on the early 70's corvettes http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=400070448241&crlp=1_263602_263622&ff4=263602_263622&viewitem=&guid=e82efb701250a0e204e73c87f9060dfa&rvr_id=&ua=WXI6&itemid=400070448241 Same was true for GTO's and 442's.

As far as I can tell, these devices "shielded" various components from heat but they did not evacuate heat from engine bay.