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THermo-tec products as heat protection to avoid percolation under hood

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I am getting  fuel percolation at both carbs due to the amount of heat radiated by the manifold. I even replaced the fuel rail with rubber hoses this weekend and was still getting rough idle under a heavy traffic at 11:00 a.m. bumper to bumper. Car started to hesitate and stalled a couple of times. However i did found this company called THERMO-TEC which provides solutions to wrap the fuel lines and wrap the heat shield extensions:

http://thermotec.shptron.com/c/heat-protection?pp=8&pg=2

Which of all the products they sell can work to wrap the fuel rail and cover the heat shield extensions?

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 Curious if there was ANY improvement after bypassing the steel fuel rail? I'm of the opinion that wrapping fuel lines retains heat that comes from the fuel rail mounts, but that's just a theory and probably only part of the problem.

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no improvement! the same fuel percolation! We bypassed the fuel rail with 5 inch rubber hose and fittings and when we got stuck on a big traffic idle became lumpy and car tended to stall.

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 Hmmm. I was hoping that it would have had some effect. Specifically, It would have taken longer for the issue to arise, or perhaps wouldn't have been as severe. Looking at your engine build and ambient temperature in Panama, an under hood fan may be the answer. I'd also consider a vented 280Z hood or louver the access panels on either side of the hood. Just for kicks, the next time you're in the conditions that cause the heat soak (traffic), try pulling the hood latch to allow the heat to escape, just to see if that will prevent the problem.

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Well if you add choke it clears up. I read that some people in Australia where there is also high temperatures are installing a 280zx injector cooling fan as per the pictures attached. Could this posible help besides from adding a layer of thermo-tec insulation adhesive foil to both of my heat shield extensions?

blower cooling.jpg

blower cooling engine 2.jpg

blower cooling engine.jpg

blower cooling engine 3.jpg

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car came with no mechanical pump! pictures above are not from my car. My car came only with an AIRTEX 8012s electric pump.

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Quote:
Originally Posted by princejqman View Post
In addition to the stock heat shield which was installed in the car by the Factory originally, i have mounted a Stainless Steel heat shield extension that reaches the bottom of both 3 screws SU Carburetor float bowls. However, the fuel percolation is still present. The gasoline in my country, Panama, has no ethanol so this should not be happening. The heat comes directly from the manifold and thus there must be away of lowering that amount of heat so it does not affect the fuel that is inside the float valves and that will evaporize and consequently shut the engine down. Other owners only throw out ideas such as swapping metal fuel rail with 5 inch rubber hoses or driving with the lid off? Is this really going to help and avoid the car idle becoming lumpy at traffic jams which leads to a sudden shut down of the engine? Wouldnt it be better to find a way to lower the temperature at the stock manifold? How about ceramic coating the stock manifold?

It's been fun but I'm done.  You have graduated to my Ignore List.

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 I don't think you're going to solve this with one fix. This is the type of problem that you'll have to chip away at. I think the blower is a good idea but it may take more than just that. Two pumps are recommended for a heat soak problem. Is your new exhaust close to the fuel lines in the tunnel?

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Mark,

I think you can really help me at this. Asides from installing the recently purchased 280zx injector cooling, should i purchase the mechanical pump and install it back again? My new exhaust is an MSA PREMIUM EXHAUST FOR STOCK MANIFOLD:

http://www.thezstore.com/page/TZS/PROD/15-6302

I am also considering pasting a layer of thermotec to both of the stainless Steel heat shield extensions:

https://www.amazon.com/Thermo-Tec-13575-Adhesive-Backed-Barrier/dp/B00029KC2K/ref=sr_1_2?ie=UTF8&qid=1495143830&sr=8-2&keywords=thermotec

Will it really help getting that manifold heat out of the way this avoiding fuel percolation at the fuel bowls? 

 

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Have you ever considered getting a used head with the stock cam and having it rebuilt by a reputable local engine shop? I still think the root cause of this problem is the California Datsun / Datsun parts LLC engine and head combination that you're running. You're throwing good money at bandaids and not fixing the cause of the overheating.


Sent from my iPhone using Classic Zcar Club mobile

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 Did the ZX injector fan make any difference? 

The extra pump can't hurt. Nissan recommended it as PART of the solution. How much good it does remains to be seen and reported back by you.

 I've not dealt with the reflective heat barrier. Sounds like a good idea. I'm assuming that the reflective side faces the headers. As I recall your heat shield is two piece. Have you considered bridging that gap?

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The zx cooling fan  just arrived i need to wire it and install it. Ill let you know thw results.  I am also attaching the description of my engine. I dont think there is anything wrong with it. I replaced the far 311 race cam with a schneider 274f including new rocker arms and springs.

20170222_141039.jpg

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On ‎05‎/‎03‎/‎2017 at 6:51 PM, Mark Maras said:

 Curious if there was ANY improvement after bypassing the steel fuel rail? I'm of the opinion that wrapping fuel lines retains heat that comes from the fuel rail mounts, but that's just a theory and probably only part of the problem.

Mark,

Just got the Thermo-tec Heat barrier adhesive:

https://www.amazon.com/Thermo-Tec-13575-Adhesive-Backed-Barrier/dp/B00029KC2K

Do you recomend just pasting it on the side of the heat shield extensions that faces the manifold? or should i also paste it on the side that faces the SU CARB fuel bowls? Please advise! I am removing the heat shield extensions today to paste the heat barrier.

 

Heat shield SU CARBS.jpg

Heatshield SU CARB rear.jpg

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 I don't know which side would be the most effective. Logically (this has failed me in the past) it seems to me that the reflective side would face the heat source but I would rely on the info and or instructions that came with the shielding product. Let us know which direction you install it and any change that you notice.

 I still have doubts about the two piece heat shield. It seems like it would be more effective if was one piece. You could bridge that gap with a third piece attached with speed nuts and screws.

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It didnt came with instructions. I guess the side facing the manifold is the one that should be covered. Please be advised that besides these 2 heat shields i have the original stock heat shield covering the center of the manifold.

THis guy manufactured my heat shield extensions!! He has great ideas:

 

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On 18/5/2017 at 8:16 PM, Mark Maras said:

 Did the ZX injector fan make any difference? 

The extra pump can't hurt. Nissan recommended it as PART of the solution. How much good it does remains to be seen and reported back by you.

 I've not dealt with the reflective heat barrier. Sounds like a good idea. I'm assuming that the reflective side faces the headers. As I recall your heat shield is two piece. Have you considered bridging that gap?

The thermotec product didnt help. Simply too much heat in that manifold. PO removed the mechanical pump and only left the electri airtex 8012s pump. Should i also install another mechanical pump and have 2 pumps pushing?

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 The original Z's only had a mechanical pump. Nissan added the elec. pump (among other things) to try to cure the heat soak problem. I can't say for sure if it will help but it can't hurt. 

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35 minutes ago, Mark Maras said:

 The original Z's only had a mechanical pump. Nissan added the elec. pump (among other things) to try to cure the heat soak problem. I can't say for sure if it will help but it can't hurt. 

Correct me if I'm wrong but the electric pump was a '73 addition.  Would that have anything to do with the flat top carbs?

The only 240s I've heard of with the extra pump had triples or modified SUs.  Supposedly the cam nose pump couldn't keep up the fuel needed. One guy I bought a z from said his Dad only turned on the electric pump when he put his foot down. Said that was a fond memory when his Dad said "flip the pump on!" they were about to run it up. LOL

 

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 I believe you're correct up to a point. I don't, however, believe that the reason for the added pump was flat top carbs. The engines used the same amount of fuel regardless of which carbs they used and the mech. pump alone supplied enough fuel to run the engine at any speed. The elec. pump by the tank added pressure in the lines prior to the mech. pump, possibly raising the boiling point of the fuel or just compressing the fuel to try to prevent the fuel from vaporizing in the lines. At least, that's my theory.

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I don't get it.  It's hot as ever outside and I went for at least an hour this morning. My carbs are almost cool feeling. My efi 280 with the aluminum fuel rail feels sorta cool too, the fuel rail. I kind of think it has something to do with the fuel? When Alabama gas flows through aluminum it cools it down. My mercury outboard would have frost on it's carbs in the spring and fall. When I deleted the egr on my 280 an older mechanic said it needed the heat in the intake.  Also said when he was racing 240s they put Christmas tree light bulbs around the carbs for the heat they created. Crazy to me why some people fight it and I've never had a problem with the six Zs I've owned.

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 I too, have pondered the why some do and some don't. The earlier the Z the less chance of heat soak, it would seem. Could it be that one of the larger puzzle pieces that is almost ignored is the fan. The heat soak problem happens in traffic (low to no speed), idling, and after shut-down, all in hot weather. It never happens at speed. At least if the engine is near stock. (the cooling system doesn't even need a fan at anything over about ten mph) So my line of thought is fan clutches. The resistance in them is all over the place, with varying ways of testing them. Personally, I've thought they sucked (definitely no pun intended) from the first time I owned one. I was never convinced that they were very efficient at pulling air, depending, of course, on how much resistance they had. A fan shroud would definitely help the alleviate the problem too, IMO.

 When the fan clutch froze up on my early 71 (metal fan), it sounded like a Cessna throttling up and it felt like the engine was down on power about 25%. Since I had a lousy opinion about the fan clutch to say nothing of the weight of that steel fan, I bought a flex fan with an extension. Previously I hadn't experienced drastic over heating. The temp would go up a bit in traffic. No heat soak problem. The flex fan did pull more air at idle. The temp didn't go up quite as high in traffic as before and it seemed like the engine revved faster. Probably because I dumped the boat anchor steel fan. The fan has to be a key element since it's job is not only to cool the internals of the engine but the externals too. BTW, If anyone with heat soak and is desperate enough:(, I have that flex fan set-up which could be borrowed to see what difference it makes, if any. 

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