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I've mentioned this in quite a few threads on the topic. Before you do anything, run a simple trial and see if the results work for your car in your weather conditions. The swap takes less than 5 minutes to do and is completely reversible. Swap the rail for rubber as I described above and repeat the conditions that cause heat soak issues. If the issues go away, you know where to start. If they persist, you have a different issue that needs attention either as a fix, or as a step in the right direction.

Hello gang! Been about 2 years since I properly saw the Z and played with it. But being on gardening leave, I’ve finally got time again. I’m using an ATi super racing damper, which has a 70mm pulley - to reduce parasitic losses. Yay for free BHP and boo for alternator spinning at just less than half speed, not producing charge at idle revs! Most alternators do nothing of note below 1200-1400 shaft RPMs. To combat this, I had it professionally rewound to produce earlier + modified a 63mm pulley on a lathe. This reduced the issue but the voltage needle still dances at idle until about 1300rpm which I don’t like, especially as the lights dim then go bright with rising revs. So, I’m about to fashion 2 other pulleys to experiment with - one with a 50mm OD and one with 40mm. To do this I need to drill out the centre of a blank pulley - for the life of me I can’t recall the size. 17mm seems to ring a bell and a nut I “think” I bought for the alternator but never used seems to confirm it. Or is it 18mm to account for the thread depth? But I thought I would ask here as someone may know and save me taking the alternator off the car and removing the pulley to measure. So come on! Fess up! Who else is man enough to publicly claim they have a 17mm shaft!?

Yes, same, it came with the flat top original configuration I inherited from the original owner. I tried to clean it up, but then realized I was probably given myself cancer and had no chance to actually get that gunk off. It didn't line up with the roundtop carbs anyway. I bought the fuel rails in my OP pics from someone on this forum. Back to topic, I should really get more scientific and measure the fuel rail temps at different times. But, not even sure it's a problem now that I fixed some fuel and fuel filter issues (again). I need to reproduce it.

Thanks for that detailed reply Jeff - much appreciated. My vapour lock issues were mainly due to idling on hot days or stopping for fuel. I found 90% of all issues was fixed by a home made heat shield that protects the carbs and float bowls. In fact my carbs are fridge cool to touch after a run and often have condensation on the domes. BUT - the super heated fuel rails bother me both from a performance and vapour lock perspective. If going the rubber route, I would suggest running it round the back of the engine and closer to the carbs where the heat-shield protects the rubber from the most extreme temps. Here’s a pic of my homemade heat-shield (those trumpets were experimental at the time and totally rubbish)! I guess the key thing is to find a way to ensure the rubber line isn’t vibrating / fouling against things that vibrate.

Hi, Do we know until when exactly this spoiler was used ?

The difference between those is only 20 thousandths. You really think that would be enough to make it not work? Did you buy some of the GM adapters to poke around with? I'm thinking there's got to be a relatively easy way to come up with something. Do you have a pic of the part you made? Neat project. Seems like the kind of non-profitable work I would get hooked into!

Appreciate it! It's a Godzilla Raceworks product. Solid shop.

Thanks Bonzi Lon. I wonder if anyone has ever flowed these different intakes and if there's enough difference to matter for anyone doing a performance build. For those of you with Rebello motors, which intake did they use on your motor's build???

It's in my other reply. I did not use a return when I went all rubber. I wanted to do exactly what you are suggesting in order to keep the rail and the fuel return, but it wasn't needed in the end. I never even unbolted the rail. I simply abandoned it in place.

I was mid-race when I tried the rubber solution, so I simply removed the short rubber inlet hose between the chassis supply pipe and the fuel rail and replaced it with a longer hose that went from the chassis pipe to the front carb area. I put a T fitting in the hose and ran a short hose from the T to each carb. I clamped the return hose off with a pair of small needle nose Vice Grips to keep any fuel from dripping out of the rail. I was able to run the next 10 hours of the race with no vapor lock in 85° ambient conditions. Prior to the rail change, it would lose power at high RPM after less than 20 minutes. The misfire would continue to get worse until it had no power. I had previously tried different fuel pumps (mechanical and electric), deadheading the fuel system, adding LOTS of various heat shields including bowl shields, swapping carbs, and propping the hood open to increase airflow. Surprisingly, deadheading the fuel helped a bit compared to keeping the fuel return. I can't explain why it helped. It wasn't a cure by any means, but it did allow us to race longer before we got vapor lock. It was only the rail delete that fixed it completely. I don't know if I have any pics. It was never pretty since it was a race car and not a street car. I'll look.

In my opinion if the fuel return is working properly, the fuel will not get hot. The rail is bolted to the cylinder head on my '72. I think an electric pump that pushes fuel constantly through the carbs and then back to the tank via the return line would keep it from getting too hot. My 2 cents only. I'm no mechanic just an observant knuckle buster.

I made a set but they extended the crank out too far so I'm trying again. I think I can get it down to just over a 1/2 inch extension. These are hand milled so they take maybe an hour to create. I will likely become more efficient by the time I make 3 pair but please, no more requests.

I like that coil on plug setup!

I'm not a fan of front bumper overriders. It makes the front of your Z look like an awkward teenager forced to wear headgear.