So, is it a good idea to polish the head, a waste of time, or did I just shoot myself (and Brian) in the foot?

Here's another pic.

I gotta plead ignornce on this one, whats the theory? I know where not talkin ports, intake rough, exhaust smooooth, but the chamber?, is it to effect propagation? If so, then ignition timing reqirements would also be involved, I think there is a question of turbulence, but I also think thats alot of shmoo, but if I`m wrong you might of went backwards, You dont want flame fronts takin themeselves out, you dont want hot spots, smooth might stectching it a bit, but it might help there, ok really stretching, theres a loss of volume to make up as far as compression, I guess nothing a wack of the head wont cure, I guess I`m back to whats the theory, it looks good, and I`m curious.

I've heard gains, and I've heard no gains, nobodys ever shown a loss. It's worth it IMO. Piston domes and exhust ports also. The reduction in oil and carbon accumulation and adhesion is huge. Just wipe it away with a rag, compared to chemicals and scraping. You sure got the suckas shiny 'ski, what was your finish grit. I usually just start with 320 and finish with rust scotchbrite and call it good

My theory was this: If there are no high spots, it eliminates the possibilities of hot spots (or at least lessens it) Also, with it smooth, the oil will not stick allowing for more oil to the rings. I really think that there is enough turbulence in the chamber without a rough surface. I'm sure the calculations weren't based on a rough casting surface. I'm also willing to bet that the prototype had a fully machined surface. The '01 head was a completely rough casting. The '02 head was rough in the 'hat' area and machined (very poorly, I might add) in the squish area. One thing I forgot to do (I'm an idiot sometimes) was get a flat plate cc on the heads. Anyone got that spec. I need to see what I have removed.

I used a medium grit Cratex elliptical point on the 'hat' area and a 3 x 1/4 fine Cratex wheel on the squish. I then switched to a 1" rag wheel and Blue Magic metal polish for the final finish. I have a couple hours, at least, in each head. Cratex is a 'rubberized' abrasive that is readily available through industrial suppliers.

Both of these heads are going to be cut so I wasn't too worried about rounding the edge. If they were to go back on as is, I think I would have tried to be more careful about rounding at the outside edge.

Originally posted by ballsout1@Sep 15 2003, 08:37 PM
I know where not talkin ports, intake rough, exhaust smooooth, but the chamber
Actually, we're going smooooth all the way from the reed cage on through. Check out the post on the porting at the top.

i was always told it was to reflect heat and minimize carbon build up.

Originally posted by tifa_5_2000@Sep 17 2003, 09:08 AM
i was always told it was to reflect heat and minimize carbon build up.
minimizing carbon= good thing.its the other that I would be concerned with,does it reflect the heat? if so ,is it going to transfer it away from the chamber fast enough? or let it build and cause a detonation problem?I can see this would be no problem on a sled that has short distance runs but on a trail sled ??? ?

yes less carbon is good. but if the heads reflecting heat down thats onto the piston, should the piston be polished also???

I always polish the chambers when I do a port and/or polish job, to remove any roughness or sharp edges for a reliability reason, warding off detonation and reducing carbon build-up. For a HP gain, I doubt it would be much if any. ???

This whole project was about reliability to start with. That's what we were looking for in polishing the head.

Have you found that it has helped? Have you cc'd the head afterward to see what changes were made as far as volume?