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Heat shield above MSA coated header


siteunseen

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I forgot to put the lower one on and the exhaust heat burned a hole in my PCV hose. It's going back on after I finish torquing the manifold down, BTW have you noticed how little torque is called for the exhaust manifold nuts? I just don't trust such a low torque.

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I'm going with 10x1.25 studs on the ends so's I can wrench down on them. 15lbs isn't much but I've read to retorque them a few times fairly soon after install. Did you put your new manifold gasket on with the metal core closet to the manifolds? The thicker side of gasket material to the head right? Oh and I thought your cylinder head was new looking at those pictures. Great job!

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I have the stock heat shield installed over my header. Of course with the SUs, I don't know how you could not install the heat shield, since that is where the throttle return springs attach.

Not so with F.I.

You know I did not know that about the manifold gasket. The one I got from MSA is a bit different then the felpro I used last time. I just looked at it installed and I cannot see a thick or thin side. 50/50 chance?? I am not sure why my valve trane is so clean the valve faces though had quite a bit of carbon build up.

good luck, looks like you are a step closer than me.

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  • 9 months later...

I have the thermal coated 6 into 1 MSA header on my 240Z. The car has early SUs and I was lucky enough to acquire an early heat shield (no cut-out for the exhaust manifold heat riser)--it's pretty small though and the headers snake out below it a good bit. Like other responders have mentioned, don't see how you could not use a heat shield of one kind or another because it provides an area to hook the carb return springs & protects the PCV hose (if used). I've seen the springs hooked on a screw, or something could be welded to the header itself to hold the springs. A larger shield would be preferable if you ask me. I wanna know if anyone has fabricated a larger one that will clear headers and offer more protection from fuel leaks? It's happened to my car once when the fuel bowl overflowed and raw gas was dripping out onto the hot header (YIKES!). And those dinky fuel hoses are certainly very very close to the whole exhaust as it is. If I had some suitable sheet metal tools, I'd try to make a bigger heat shield...only downside is that it would spoil the cool factor of oogling the headers, but form should follow function especially when heat is concerned.

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  • 8 years later...

Fit some efficient heat-shield material and run it from engine head to chassis rail.

https://www.google.com/search?q=nimbus+heat+shield&rlz=1C1VSNC_enFR576FR576&oq=nimbus+heat+shield&aqs=chrome..69i57j69i59j0i22i30l2.4227j0j7&sourceid=chrome&ie=UTF-8

There's a lot of turbulence behind the radiator - does anyone seriously believe the the hot air rises only vertically ?

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2 hours ago, jalexquijano said:

Cannot get rid of this heat in my 1972 240z with twin su roundtop carbs? Car still misfires after 5 to 10 minutes in stop and go traffic. I thought i had a problem in the engine and the problem is clearly heat. Any advice on how to tackle this?

 Have you ever tried driving with the hood unlatched to see if the problem reoccurs? It'd be an easy experiment.

@rossiz louvered his inspection covers on the sides of the hood. I don't remember if heat was his reason for doing so but it looked good and I'll bet it lowered the engine bay temps.

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 Prior to changing the radiator in my 71 240 I had similar problems in stalled and stop and go traffic. I found the best solution at that time was to turn the engine off until traffic moves again. The Z would restart with a click of the key so it was little inconvenience. Also, when in slow traffic, keep the rpms as low as possible. Every time a spark plug fires it produces more heat.

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What does your TEMP gauge show. My needle stays on the right "leg" of the M and my other 240 was the same exact way. If I'm not mistaken Nissan has a 165F thermostat and a 180F. Are you using a thermostat, is it a Nissan because the cheap ones are no good.

Do think the motor is actually hot or are you thinking it's the fuel in the carbs percolating?

The "pop pop pop" means it's not tuned properly. It could in the timing or ignition or the carbs, any number of things.

The last I remember you had found an L motor experienced mechanic. What happened with that? 

I think an infared temp gun would be money well spent. They're pretty cheap now. Point the red dot and see where it's hot.

https://www.amazon.com/Infrared-Thermometers/b?ie=UTF8&node=9931459011

Good luck with your problem.

PS Back the timing up and remove the air filter, then see what it does.

PSS Read this thread if you have time.

 

 

Edited by siteunseen
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I got rid of the pop pop pop today by tuning the carbs to 4 turns clockwise both and rpm set to 1000. Now i need to knock down the heat that makes my car stumble snd misfire after 5 to 10 mins stuck in traffic. Any recommendations other than removing the fan clutch and installing dual electric fans?

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4 hours ago, jalexquijano said:

Some mechanic over here told me i should consider investing in ceramic coated header? Will this help?

Mine runs "warm" even in the heat of our summer here, high 90s farenheit.

My carbs domes are cool to the touch after driving. Good flowing fuel and the ceramic header I guess. Also no coolant flowing through them.

Try a digital thermometer in the radiator while it's parked, no air flow other than the fan. That is like traffic jams I would think. Mine runs at 175 farenheit with the thermostat open and coolant flowing.

post-24724-14150829443689.jpg

 

 

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Well i do remember  shutting the water flow passage that runs on the back of both carbs by removing the intake manifold valve to reduce any kind of heat. My car also has the antibackfire / smog emmission system removed. Any recommendations on how to tackle this misfire caused by overheat when coming out from traffic jams?

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The last photo looks like your heater core is bypassed? I’ve read about bypassing it and that it’s better to plug the fitting at the back of the block rather than looping it. I guess this is how the factory heater core works (stopping flow, not rerouting). Perhaps this could help? 

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