How wide to take ports on 359

[Zombiechopper]

I have a 359 top coming to go on my never ending problem drama queen 357.

How wide should I take the ports? Ring ends and skirt don't limit port width, so how wide do you go? I think when I ported the 357 the first time I aimed to match the widths on my ms361 because I knew that width worked.

I seem to recall a formula or rule involving a percentage of bore diameter, or percentage of circumference maybe? and then there being a debate if that was to be a straight line or following the radius of the cylinder. What was that ratio?

 

[Zombiechopper]

I'm going to run stock timing because TW says this about the 359:

Don't try to run 180 degrees of exhaust durration and 170 on intake. In other words don't try to mess much with the factory timing. The 359 can be made to cut nearly twice as fast as bone stock without straying more than a few degress from factory port timing.

I have 170 intake on my 357 cylinder ;( ooooooops

 

[ncfarmboy]

I have a 359 top coming to go on my never ending problem drama queen 357.

How wide should I take the ports? Ring ends and skirt don't limit port width, so how wide do you go? I think when I ported the 357 the first time I aimed to match the widths on my ms361 because I knew that width worked.

I seem to recall a formula or rule involving a percentage of bore diameter, or percentage of circumference maybe? and then there being a debate if that was to be a straight line or following the radius of the cylinder. What was that ratio?

65%-70% diameter of bore. Do a port map then measure map. Then measure straight line in the cyl. Debate over. 47mm x .65=30.55mm 47mm x .70=32.9mm
Shep

 

[Zombiechopper]

thanks.