cooltoys61

What range is safe for 454 mag?1200F?1400F1500F? Where should I drill into the stock manifolds and can I do it where I won't hit the water jacket? I'll be running a stock 750 DP,any guess what jets to start with for 5 psi boost?

Kanookstr

I put mine here, I know you want them to be closer to the head, but I ran the motor with the egt installed on the motor when it was stock. so I had a base line stock temps to compare with for when I installed the procharger.
In the stock manifolds theres a web right where I drilled for the probe, so I didn't go thru any water jackets. You have to use the ultra thin probes though (5/16") I know the picture is of Gil Manifolds, but in the stock mercs I was in the same spot. When you take the riser off, you will see the web I am talking about.
Good luck.

BTW, I was shocked to see the stock temps over 1450° in that location... I was seeing around 1350° after the procharger install, then when I installed Gil manifold and risers, I went down to 1250°

Kanookstr

#2

mcollinstn

Gils have a spot on each cylinder right out of the heads where there is meat to do this.

Kanookstr

Yes They do, I have that diagram, but it was to tight of a fit at that location for my engine and heads.

tomcat

Nice install Kanookstr. You definitely want to see 1250F here since some cylinders may be hotter than that average.

cooltoys61: I strongly recommend buying a modified blowthorugh carb from someone who knows how to do it. It can save you a lot of time and grief. Keep your stock carb for the day you sell the boat without the supercharger.

Changing jets is secondary to getting the carb to respond to boost. This means using the power valve metering passage to move a lot of the fuel. Otherwise to get the carb rich enough for boost you will be using jets that are too big for other ranges of operation. We have had good luck with carbs from Nickerson Performance. He uses his own metering blocks.

This is a Nickerson carb...