I am currently working on a set of 416's which I am port& Polishing. I did the intake ports & intake bowls and that was no problems...turned out how I would expect.

Went through and did the exhaust ports and exhaust bowls....with my first sort of pass through and worked my way up in terms of grit of bit used.....it looks fairly smooth but not "mirror like" which it shoudl be. I have that standard abbrasives kit and tried using those cross buff things but I cant get them into the ports...they seem like they are too big to use....have any of you guys encountered this...if so what did you use to polish them???

Also...in terms of polishing the combustion chambers.....I cant seem to get these things cleaned up etc.......there is tones of carbon/rust/whatever else in them.....do these have to be "polished" or is it alright to just sort of clean them up (with removing as little as possible metal etc).....suggestions or to I just have to spend some more time on things???

Thanks,
Dave

 

Stuff the crossbuff into the port & let 'er rip. Use lubricant like they suggest. It'll fit easier into the later ports...

The carbon should have been removed before you started the port work. There are two camps about the effectiveness of polishing. Personally, I lean towards the "polish them up as suggested" camp for the purpose of eliminating hot spots.

 

did my 416 's a couple of weks ago ,

use thos crossbuffs in the intake ports , you will notice they will wear slowly by the time your done the intake ports they will fit in the exhaust ports make sure you shine the whole thing up , this job done well should take you 30 hours ,

by the way polishing the combustion chambers is impossible to do on mine because the casts were to ruff , i just cleaned them up the best i could ,

have fun dude

 

You don't want to polish the intake ports. Like the instructions say, you want to leave them a little rough to keep fuel from separating from the air as it heads for the combustion chamber.

I was able to get the chambers of the Worlds pretty well polished, but I found the 081 practice head and the 396 heads were a lot harder to get all of the casting roughness out. On the 396, I just got what I could with the 80 grit, then used the crossbuffs to polish as much as possible. There was a little roughness left, but nothing like the sharp peaks that existed as-delivered from the factory.