carbon on pistons

[gjp]

As I am cleaning the heads I see a lot of carbon on the pistons. Should I clean them. I have been told yes and no?? If yes how and with what. And how clean does the surface of the block have to be for the new heads?? I used a razor scraper and some brake clean and they are smoth and clean but still have the imprint of the old gaskets still? Thanks guys!

 

[jwaller]

Re: carbon on pistons

if it's a little carbon I wouldnt worry about it. if oyu think it's too much then carb cleaner should be all you need. Deck surface needs to be clean. I used a wire wheel or plastic wheel on a air tool. be careful to keep the junk out of the motor though. if your block has impressions by old gaskets then it might need to be decked to straigten it out, but I havent ever seen the need for this on our motors. are you seeing an image or can you feel an impression?

 

[Wikid 1]

Re: carbon on pistons

Take it all off. Carbon is BAD it holds heat and will cause detonation, also there's a reason its there, you need to find it and fix it, usually it's from running stupid rich. also be extremely carefull! if a piece gets into the ring land it will ride the ring up and down and put a nice little groove into the side of the bore, lots of carb cleaner, a blow gun, and lots and lots of patience also if your really ambitious, get some 600 grit sand paper and polish (yes polish) the piston crowns, the smoother it is the more heat it will reflect, and try to make it as shiney as possible, more shine means less ridges, which means less surface area to absorb heat.

Surface needs to be clean to the TOUCH, as in smothe when you run your fingers across it. in some cases it's just not possible to get all the old silver off without decking the block, and be carefull! i like either the plastic "finger" type scrapers on an air tool, or i really like the 3M "Ro-loc" pads, but don't dig into the block at all, you can remove metal and cause an imperfect sealing surface and gaurentee blown head gaskets. I'd also reccomment new head bolts as well, also clean the thread holes with a NEW tap, go to a good parts store like NAPA or such, and tell them what your doing and what you want, don't get a cheap one either!

As far as keeping the shit out of the block, try as best as you can, but it's not possible to be perfect. especially down in the valley. I drain the oil from the motor just before i'm ready to put it back together, then leave the drain plug out, and pour a quart or so of Kerosene or Diesel down the valley to be sure to rinse it out good, and follow that with a quart of cheap-o oil and let it drain, and assemble, change the filter, and fill it up with new oil and your golden, never had a problem since someone taught me that. and i've changed ALOT of intake/head gaskets

 

[gjp]

Re: carbon on pistons

its just the image of the old gasket. running my fingers accross the block and its smoth in all but a few spots.
pistons 1 and 6 had some heavy carbon and a few white spots witch I read somewhere was signs of detonation? I used shop towls to plug up the holes and I am trying my best to keep crud out.
I found the tap tip from the GN web site. What should I use on the new bolts. Oil, thread lock, I have some teflon thread lock??? Yes, They are arp 12 point head bolts.

Thanks guys, this is my first time so any info is helpfull.

 

[gjp]

Re: carbon on pistons

I set the piston at tdc sprayed carb cleaner. let it soak and the carbon flaked off with a plastic scraper. I cant get into the groves but the cleaner got most of it off. Polishing...sounds like a good idea, but with my knowedge I wont try that. The pistons are about 95% clean and are a light tan color. There are still a few pitted spots on the block surface. Should I sand them??

I remember a pic on torque sequence for the heads?? What should I use for head bolt lube and what final torque should they be set at?

 

[gjp]

Re: carbon on pistons

What do you think. I soaked the piston in seafoam for 30 min. used a plastic home made scraper and cleaned it off with carb cleaner. you can see the one that I did not do.