Okay, I know that it will keep the carbon from building up but does that really hellp a lot? Been finishing my heads and polishing the chambers at this very moment and was just wondering if its worth polishing chambers.

 

Eventually that build up will cause pre ignition. Keep on the polishing.

 

It also helps speed the exhaust going out.

 

It's pretty... .

I'd polish it up with 120grit or so where you unshrouded, and leave it at that.

 

Hey Phil...that's it??? It's pretty lololol. Anyway I went to 120 then with cross buffs. It;s pretty shinny. What do you mean by "unshrouded"?

Phil you never gave me a tip on the exhaust ports. I remember you said they already flowed well on the LT1 heads but where do you take the majority of the material off of? I took some off around the guides and the roof....kinda smoothed out the hump in the roof. Thats it. Should I have done more?

 

That's the best answer, IMO.

 

ohhh philllippppppp.....

 

I got a set of rebuilt LT1 aluminum heads the other day with new valves (1.94/1.50),locks, retainers and springs for $200.00 and I want to polish the chambers also. I already used 220 and got them shiny but 120 is next. Any use in sanding the bump in the chamber on the out side between the valves down? Is this what they are talking about when they said "unshrouding?" I know it would lower compression a little. I read in Chevy High Performance that this swirl polish reduces carbon and makes for better flow through the chamber but not a gain in power, just a gain in efficiency. I'll try to take some pics of the heads in a day or so. Hard to find time(deer season just started!!)

 

Polishing the chambers will alleviate those sharp edges and casting flash which may become hot spots and contribute to detonation/preignition. A lesser known advantage to polishing the chambers is decreased heat conduction to the head itself. Heat of course, is what an engine is all about. If heat is unnecessarily lost to coolant (via the head coolant passages), cylinder pressures will drop and power will decrease. A cooler head also decreases the operating temperature of the valves and guides, which decreases guide wear. Hopefully you already know to take out the absolute bare minimum material from each chamber to prevent a drop in compression ratio. Probably around 1.5 to 2.5 CC per chamber max with most of the material taken out in the deshrouding process. Fortunately, valve shrouding is not a real problem with the design of the LT1 chambers. The material removed from the chambers can be offset by milling the heads around .015". Use the thinner LT1 head gasket (.039" compressed) as opposed to the stock .049" (compressed) head gasket. I personally prefer a 120 grit finish (cartridge rolls then flapwheel) followed up with a crossbuff/lubricant combo. I'll occasionally use a stone for initial removal of casting flash in the chambers, but never a carbide (too aggressive). Dont forget to decrease your regulated air pressure when spinning the crossbuffs.

 

Did all that GA93. I started with 80 grit to get out the bumps and crap then went to 120, then med crossbuff and then fine. I don't know why ninetythree is going backwards. Dude you go with the smaller number than the finer ones. In other words....120 then 220. Get finer to get the polish job.