M-Boat Carb Block

Product Review Article...



A new updated CNC machined aluminum carburetor block from M-boat...






This is an update to the aluminum iso-block from M-Boat. You can read our review of the original block below.


At first sight most would think that this carb block is just like the original version, but there is one major difference...and by looking at the engine side of the block it is very obvious. The designers at M-boat have decided to use a different approach in the way they machined the recess for the included Teflon gasket. The grasket cutout has been made bigger than the actual intake port and the aluminum from the block protrudes through the gasket to match up against (or very close to) the intake port.


The match between the intake port and the block are very close with only the upper corners being a little bit off, but this is minimal. The new design seems to provide a very smooth transition between the block and the engine. Although I have never hade any real issues with the Teflon gaskets, one of the reasons for this new design is to prevent any expansion of the gasket into the port when tightening, or after many re-installations of the block.

The overall thickness of the block has been reduced slightly also, measuring in at 15.5mm ( approx. 0.612"). Here is a quote from M-boat on this subject:
"Thinner than our previous version for stronger and cooler airflow charges into the cylinder. As we know that the cooler air intake holds more oxygen for any given amount, so larger amount of fuel can be injected causes more power from that same engine."

Aside from these points, everything else I noted in the original review still applies. A very nice piece from M-boat!

Original Review Starts Here


This is an aluminum carburetor isolator block by M-Boat designed to be a direct replacement for the stock iso-block supplied with Zenoah engines.


The carb block is machined from billet aluminum and is supplied in different choices of anodize finish. The machine work is perfect as is the anodizing. As a heat barrier between the engine and the carburetor, the block is supplied with a thick Teflon gasket to fit between it and the engine.


To install this block you will have to remove the carburetor and stock iso-block from your Zenoah engine. You will have to keep the stock screws and carburetor gasket as these are not supplied with the carb block.





After removing the stock parts, make sure the intake port face on your engine is clean and free of gasket material that may have torn off from the stock gasket. Install the Teflon gasket in the carb block making sure to line up the pulse hole in the gasket with the hole in the carb block. Using the stock screws, mount the carb block and gasket to the engine cylinder. Next you will mount your preferred carburetor to the block using the carb screws and the stock carburetor gasket (use a new gasket if you can). This is where I ran into a problem. The stock carburetor screws ended up being too long when I installed my carburetor and they pushed up against the Teflon gasket. I was expecting this to happen when installing an aftermarket carburetor such as the Walbro 257 (pictured) but I also tried the installation with a stock Walbro 644 with spit tube (that comes with stock Zenoah engines) and the stock bolts were still too long. I therefore had to shorten the bolts to ensure proper tightening of the carburetor without interfering with the Teflon gasket. It is an easy fix, but nonetheless needs to be addressed.




That's it for the installation of the carb block. A simple way to bolt on a carb isolator that will not deform (unless excessive force is used).





What I liked about the kit:


  • Great machine work and finish
  • Different colors available
  • Good match with the stock intake port on Zenoah engines
  • Smooth transition from port face to carb
  • I like the fit of the gasket in the recess in the back of the carb block
  • A sturdy piece
  • Will not interfere with most throttle linkages on the market today



What I thought was missing:


  • Mounting hardware (bolts of proper length, stainless steel preferably)
  • A carburetor gasket (hate to reuse an old gasket) : users might not always have a new one on hand




Final thoughts...


Another nice product from M-Boat that incorporates quality and good looks!



Happy Boating!




Product Information:

Carburetor Block for Zenoah: $35.00 USD ea. (price may change...see website for updated pricing)


M-Boat USA

Web: www.mboatusa.com



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