Ive decided to get my headers ceramic coated. Both Jet-hot and HPC cost about the same. At the moment There is a lot of heat generated in the engine bay. I have a non-vented hood, a round top su's, and a rx-7 electric fuel pump.

I still get a little vapour lock when its a warm day, say 25C+ and ive been driving for a fair while. Ill stop at lights or something and im there for a couple of minutes ill "chug" when a accelerate away.

I dont have a heat shield, should I get one, or fabricate one as well as the ceramic coating? Anyone else get this prob with unwrapped headers?

Cheers

John

I have the ceramic coated headers with the heat shield for the round tops. Never had a problem, even on those extremely hot days going through Arizona in the summer with the A/C running.

I used hpc in Brendale, Brisbane. . . .they did my turbo exhaust manifold, the exhaust snail, my piston tops, valve tops, the shield that goes between your inlet and exhaust manifold, my inlet manifold and heaps of other stuff. A friend of mine had a very quick Z with webbers and a lot of other work and we went to Lakeside for a bit of a session. . .. after a good flog around the circuit, his was cooking under the bonnet. . .I mean paint around the extractors was being discoloured, where mine was as though I'd been for a drive down to the shops for a loaf of bread, so Im a bit of a convert.

Cheers - Simon

Guess that settles it. Prolly do the intake as well then... money money money.

Ill tell ya what i think of it.

Got them back finally! (NOTE: Even tho HPC will promise it'll be ready in 5 working days, allow 9):tapemouth . The finish is fantastic in the silver/polished colour. It has made a noticable difference in underhood temperatures, Although in the summer heat I still need to insulate the fuel lines.

If I had the time and money I would get the intake done as well. But i dont

Just if anybody was wondering...

Just wondering how much it cost?

Thanks

A vented bonnet helps too, trouble is the 260 vented bonnets are a lot heavier than the non-vented 240 ones.

Sorry to hijack the thread.

Just looking for some more ideas to help my vapour lock problems. As is I now have a high volume electric pump and I've also built a quick dodgy aluminium heat shield between the carbs and the exhaust manifold.

However the carbs still get incredibly hot when I shut the car off on a hot day (been 40?C lately). It'll always start up fine, but will die after about a minute, usually when I'm pulling out onto the road. After that it wont start for a good 15-30min. *grrrrr*

Does that sound more like the fuel boiling in the carbs, or still somewhere along the fuel lines?

The heat shield helped a fair bit, but it still will get rather hot under there when you turn the car off. The only solutions I can see are either a vented bonnet which I don't like the look of and can't afford anyway and my other idea was to install a small therofan at the front of the engine bay to keep some cool air flowing over the carbs for say 10 minutes after you turn the car off.

Sounds like a reasonable idea? Any other ideas?

Thanks,

Justin

Here's a pic of the setup if it helps at all.

Originally posted by Datto-Zed

Any other ideas?

In the USA, when Nissan had problems with the Flat Top SU's and heat soak causing problems, they insulated the fuel rail with a set of small blankets that were aluminized on one side and some sort of insulation like asbestos fibres on the inside. They surrounded the entire fuel rail with these. I would consider some sort of passive system like that before engineering a more complex system like a timer or temperature activated fan.

Just my (Cheap Assed) $.02

Carl

Do you think it would be the fuel boiling in the fuel lines though, considering I have a electric pump pushing a good volume of fuel?

I was thinking it would be a case of the fuel boiling in the carbs/bowls, but now keeping in mind it will run for about a minute as I idle it around and then die, that sounds more like the carbs aren't getting any fuel and it dies after all the fuel in the bowls is used? Sound plausible? How long would the car be able to idle for with only the fuel in the bowls? I might give that a test tomorrow.

Does the fuel system recirculate? If so, the electric pump will be constantly pushing fresh petrol through the fuel lines, in which case there should be no vapour locks.

My '77 had that sort of stuff Carl mentioned wrapped around the lines so I guess that Nissan thought they were vulnerable. Your heat shield looks pretty good, Justin, but with the carbs sitting above the exhaust and no way for the hot air to rise out it is basically a design problem.