Hi guys,

Just disassembled a B20B for a budget B20VTEC. Wondering if these marks on the cylinder walls are acceptable. All 4 cylinders have the darkened marks on both sides (intake/exhaust sides) which I presume is from the non-vertical rod thrust. All 4 cylinders also have the two thin marks at the begining of the water jackets inbetween cylinders (i.e. all side walls except for cylinders 1 & 4 on the ends). I presume this is from hot-spots forming where the coolant doesn't circulate well, or perhaps just the way the cylinders expand under load?

The walls are completely smooth all over.

1) Can I get away with leaving the walls intact?

2) I was greeted with a non-OEM headgasket. Obviously no one changes the HG for no reason. Should I deck the block just incase? [my B16 head was decked] (I have no straight edge to check for flatness and one would cost as much as machine work). The tops of the cylinders have plenty of gasket material on them (which will probably scrape off) but also some exhaust black spots (can kinda see in the photos) which won't come off?

3) The block has obviously been sitting around for quite a while. There is a slight knock in the bottom end when I rotate the crank back and forth. I've not got the engine on a stand yet to further investigate but is it possible this is a false alarm from oil draining out of all the bearing clearances?

All thoughts appreciated.

 

1) you'll need to borrow a bore gauge to find out if those dark spots are acceptable...I seriously doubt they are within spec, and to correctly build they will probably need machined, Can you get away without it???? who knows, depends on the depth and how much power you plan to make. It will also cause some smoking for some time until the rings get worn in.

2) I always deck blocks of unknown origin (or at least have them checked), it sucks I know, because machine work is expensive. You're absolutley right about the head gasket and overheated. Why deck your head but not the block?

3)how bad is this knock? For the most part, the noise of changing directions should be very very minimal,maybe even non-noticable. Is there any thrust movement of the crank? I would definetly be stripping the bottom half to inspect every bearing and clearance.

 

1) I live by the philosophy of investing in my own skills - therefore I will buy a dial bore gauge. Stock specs allow for up to 0.07mm over the stock bore; a gauge with 0.01mm increments should be ok for that or should I avoid the cheap(ish) ebay items and find a more precise tool?

2) I decked the head for a previous setup where I knew that the block hadn't been overheated but the head was of unknown origins. Removing the block from the car wasn't an option but this time round it most certainly is.

3) It's not very noticable, just a slight tap. I'm getting it up on the stand this weekend so I'll check for thrust play then. I was planning to keep the rev limit to around 7200 and use the stock rod bolts to avoid removing any rod caps, but I might aswell get some ARP bolts since I'll be mucking around anyway.

I planned to do a stock block B20VTEC and bang it together quickly but it looks like I'll be stocking up on some new tools and completely rebuilding. I'm not looking for all out power - I'm using a stock B16 head with GSR cams. From the performance of builds I've seen on here, I'd be happy with the Australian equivalent of 180whp (I was going to settle for far less with the stock low comp B20 block). Just looking to have a nice and torquey motor for the track (something a bit more exciting than the B18A) a few times a year yet be reliable enough to last for years as my daily driver.

 

You can find a nice central tool bore gauge on ebay for cheap. I found a "sled" type for $20.....Then I found the nice "periscope" one I wanted for $80 brand new. The deals are out there, sometimes you just have to be patient. Also central makes a sub-brand called storm, although I have never used them. I know central isnt top of the line but their products work great for what we use them for. Keep an eye out for gently used starret, mitutoyo and other top end stuff. Heres a website Ive used to find nice stuff, but shhh dont tell anyone
http://www.odysseytelevision.com/C80...gital--1i.html

I would personally deck the block, other then that, tear it apart and at least check the bearing clearances and thrust