Datsun Roadster Forum-311s.org

I fixed a slipping supercharger belt problem before the last race of the season in November. It really ran well for about 30 seconds. It then started to miss really badly. We ran the remainder of the race in Dennis' Mustang. I finally got the motor apart this evening. It had the milkshake oil problem. When I got it all apart I found 1 blown headgasket, two spun bearings, three broken pistons, and a partridge in a pear tree. It really isn't as bad as it could be. About an inch of the netal sealing ring around the bore in the headgasket was gone. It looks like a bit of the metal may have gotten in the rod bearings because two of them have scratches through the coating and into the copper. The journals look fine with no scratches or anything. Three pistons have broken ring lands but no missing bits of metal. I have an ARP head stud kit and a metal headgasket to put back on it. I will buy a new set of pistons and rings and replace the rod bearings. I don't think I'm going to do any additional rebuilding past that. I think that the months where it was running poorly from injection problems caused some detonation which eventually broke the ringlands and headgasket. I'm going to install Frontier truck pistons because they are lower compression than the 240sx ones.

Later,

Broken engines suck! Detonation is hard on pistons. Cost is probably an issue, but you may be better off with forged pistons than stock replacements. Is the metal head gasket a copper one or a MLS type?

Mark

MLS from Cometic.

Nice!

Mark

I ordered new pistons, metal headgasket, and rod bearings. I got Frontier pistons because they are lower compression. Yesterday I worked on a bunch of preparation because the parts had not arrived yet. I swapped the calipers from side to side on front because I had them backwards. The Outlaw 2000 calipers have small pistons and large pistons. The small pistons are supposed to be the leading pistons but I had them upside down. I also placed the porportioning valve in the front circuit instead of the rear. The fronts were doing all the work and would lock up. The rears didn't seem to work at all. I replaced the ignition switch, shifter bushing, output shaft seal, and a bunch of other small things. I also prepped the motor for the new pistons. I honed the bores, cleaned the gasket surfaces, and installed an ARP headstud kit. I now have the pistons and will assmeble the motor today. I think I can have it installed and running by tomorrow. The first race of the season is Sunday.

Wish me luck,

Andy

It runs, drives, and stops. My marathon three day rebuild seems to be successful. It started on the first try after I hooked up a non-DED battery. Actually, it was just "Mostly Dead". There was only one small problem. One of the supercharger idler pulleys was not turning. We'll see if it holds up tomorrow. It is scary taking out a motor with new pistons, rings, and bearings with no real break in time. There isn't much I can do. It isn't street legal so idling in the driveway and a short trip around the block is all the break in it will get.

"Have fun storming the castle."

I was wondering if anyone would get that.

Won my class. Picked up 4 seconds on a benchmark driver compared to last season. Car ran great.

Inconceivable!!!! Even though it's almost a chick flick, I love that movie.
Apparently the rebuild worked well!

Scalded cat on shag.

I had to install yet another headgasket. This time I decked the block (by hand) and installed a new head. The head was rebuilt with new valves and seals and was surfaced. I checked the old valves by filling the ports with water and looking for leaks. 5 of the 16 valves leaked water. I was lucky to find the rebuilt head on craigslist for less than it would cost to rebuild mine. The only problem is that my motor is a 91-93 and the new head was a 96. There are two differences that I have noticed. First is that the bosses at the front right and rear left that I typically use to pull the motor are quite a bit beefier on the 96 head. This isn't a big deal except that my motor sits in the notch under the cowl and it wouldn't fit. I had to clearance the cowl with a 5 pound clearancing tool. The second is that the valve cover is physically different and the older one will not bolt on. I had to make an emergency junk yard trip on the day before a race to get the right valve cover. Other than that it is a direct bolt-on. The new head made it through 2 autocrosses with 12 runs each, A total of 24 runs without overheating or breaking down. This might be a record. I have noticed that boost is down below 10 probably because some of the teflon on the rotors has flaked off.

I have a datalogger called MaxQData. It maps the autocross course using GPS at 10hz which much faster and better than your normal GPS. It will display things like speed and g-forces and horsepower. During the last event I had new tires and the car seemed to be hooking exceptionally well. It maxed out at 261 horsepower to the ground. That isn't far off from my estimates. You can see some crappy videos on youtube under my username of bucephalus1968.

Later,