To all Triple Mikuni Owners:

Please share your knowledge and tell me what size fuel line you ran to your triple Mikuni's...........thanks in advance!

40mm Mikuni's - Wolf Creek Racing Rebuilds

I have been told: (Todd @ Wolf Creek Racing):

• Remove the current fuel rail
  
• Remove the current Mech Fuel Pump
  
• No return fuel line required
  

Run:

• Tank to-
  
• In line Filter to-
  
• Electric Fuel Pump (5-9 psi) to-
  
• Fuel Pressure Regulator 3-3.5psi to-
  
• Fuel Filter to-
  
• Carb-Carb-Carb- dead head at end
  
• Heat Shield - yet to be fabricated - (does anybody have one you would like to sell - if so PM me)
  

Todd is jetting and setting for my engine particulars and driving style (show and weekend cruising - never to be tracked). I elected not to go with the 44's due to just really not needing the extra power and air.

Please post your Mikuni pictures so I can see your fuel line set up and the method you ran it -I know I want to keep the fuel lines away from the block and heat as much as possible - I think I am going to use a black braided fuel line like:

http://www.k-tuned.com/store/product_info.php?cPath=11&products_id=65

Please share your fuel line sizing and any insight you may have for me with my upcoming adventure with Mikuni's

I'm not sure what size hose I'm running, but it is slightly wider than the stock feeds to the SUs. As for the lines, I don't see why a return line would be bad and the Z is already set up for it anyway, and why remove the rail for that matter. I kept the fuel rail (and the mechanical pump as well) and am using the return on my triples.

My suggestion:

Tank > Filter > Mechanical pump > Rail > Hose into front carb > Connect carbs > Last carb feeds back into the rail > Return

If you want to run a fuel pressure regulator, then place it after the carbs with a return line present and you now have better regulation and fuel flow since you are regulating the back-pressure and have a bypass for excess fuel. Only excess fuel goes past the regulator instead of the method you mention, which would put a restriction without a bypass and effectively heat the fuel before it even gets to the engine bay. Plus, with a dead-headed setup the fuel then has nowhere to go and further heat up compared to a return line and a back-pressure regulated system.

Of course, I am not saying that your setup won't work and I'm sure many have used it and were okay with doing so. However I prefer the better option especially since the car already has the required provisions. If your Z is just a street cruiser then you probably won't have a problem with the way you were originally told.

Nissan made/makes a triple carb fuel rail without a return so you don't need one either. But there is no point removing the stock return steel line if you don't need to. The stock fuel line will deliver plenty of go juice for your 40's.

Nissan made/makes a triple carb fuel rail without a return so you don't need one either. But there is no point removing the stock return steel line if you don't need to. The stock fuel line will deliver plenty of go juice for your 40's.

Right. As I said, it'll work, but a return line is better.

Nissan made/makes a triple carb fuel rail without a return so you don't need one either. But there is no point removing the stock return steel line if you don't need to. The stock fuel line will deliver plenty of go juice for your 40's.

Like mine

Thanks to all that have posted so far!

Chris - can you tell me about your fuel rail, heat shield, and the size of your fuel line please?

Edited March 26, 201113 yr by Travel'n Man

I ran a 3/8" hard line from a filtered electric pump at the tank into braided Aeroquip line, through filter, then to fuel block, then to each carb. Gauge installed on block. No return line, no mechanical pump. No heat problems. Fuel pressure <6 psi.

Hope this helps.

Frank

Frank -

Great looking setup and I'm sure she runs great! How did you attach the fuel block?

Bolted to the intake/exhaust bolts from the head.

I was quite surprised that the heat soak from the head/exhaust didn't boil the fuel, but it's worked quite well since early last summer. This car has never exhibited the vapor lock problems that other Zs have had. I don't really know why, either.

I'm trying to do as much research as possible so I can plan out my fuel distribution and keep things as cool as possible. I'm really surprised that Nissan ran the original fuel rail where they did. I may come across the front of the block (by the water pump) and dead head to the carbs with no return. Todd at Wolf Creek Racing said to do away with the current rail and return system. The new system would only have 3.4 to 4 psi and if I can keep the fuel away from the intake area then the hot fuel issue should no be an issue (hopefully).

Frank - what did you do for a heat shield?

Edited March 27, 201113 yr by Travel'n Man

The Mikunis came with a heat shield under the carbs. You can see it in the third photo.

So far I can only find one heat shield that is made with a "lip".

http://www.zccjdm.com/catalog.php/azcarbum/dt47542/pd1277652/HEAT_SHIELD__DRIP_PAN__WEBER_SOLEX_MIKUNI_

I reviewed hundreds of internet sites - links -youtube postings. It's amazing how many setups do not include a heat shield. I would really think that would be a necessity, not an option.