Silver Head MAC .67 questions

[topfuel443]

Guys, I need a few recommendations. Just got a .67 MAC silver head for my new scale boat. I have never run anything other than .20's and a few gas eninges. whats a good pipe length and the best pipe for this engine? what about head clearance?

Thanks ~ James

 

[nitro junky]

I use the Andy Brown 67 parabolic pipe set at 11 in. with .012 head clearance. You can also use the AB 67 pipe set at 10.8 in.

NJ

 

[TimD]

Topfuel,

Check that the rotor housing is bushed! If not get in touch with CMD.

If you use the parabolic pipe you may have to drill out the stinger.....

Tim.

 

[topfuel443]

Tim, tore it apart last night, and the rotor housing is bushed......is this good or bad? wasnt sure in your reply.

Thanks for the pipe length and head clearance Nitro Junky just what I was looking for!

What were the differences in this engine and the blue head engine? (other than the color of the cooling jacket ;D )

 

[TimD]

Bushed rotor is good!

 

[topfuel443]

whewwww! ok thanks for the tip.

~ James

 

[PHIL THOMAS]

The siver head can have some cooling problems in a scale hydro, try it, and if it runs hot get the blue head for it ,, the blue head has much more volume for water, the whole head button is cooled, not just the channel in the head you have.

Also you will want to run just a little longer pipe lenght in the scale

maybe set it at 113/4 to start and shorten it till it fails to respond and go up on the pipe easily.

Run all the fuel lines with LARGE SIZE tubing and use a tank that is minimum 16oz.. be sure the carb venturi is not close to any cowling, at least 1/2 inch clearance,,it will not run well and lose power.

Run the boat with a x455/3 or x457 prop to start off depending on your set up and running weight dont load the engine and let it use the rpm. If the boat seems to run well try the next size prop for more speed..

PHIL THOMAS http://www.stonerracing.com/rcmd