Second coming, i agree about clearances. Getting them right is about the half the reliability battle. On a vaguely related note, does anyone have all the necessary tolerances and clearances for an abf. I've got 8v data coming out of my ears, but nothing fora 16v. I'm not too confident using a haynes either, since they're frequently wrong. Just need to start learning to build 16v's now. Cheers.
explain? about thrashing it to get the rings seated properly... great, but only if you've just doone the rings... it's not just the rings you need to take care of usually on a bottom end rebuild.
Vim just being an abrasive powder, seats the rings a bit faster. Like Ian said though, not for a road engine! If you build the bottom end properly, it'll take virtually no running in. As an example - on the big yank V8's, they are run in on a dyno. A high-spec engine (obviously properly built, with all the clearances checked and bearings matched) is run in on the engine dyno in around 3 runs - 5 mins at low revs for the cam (if it's not using a roller cam), then to redline until it gets hot. They let it cool, then do the same twice more. Job done, and those engines will go on forever......
I've also read that article and the outcome. Basically they found the engines that had been ragged from new made more power <10bhp (if I remember correctly) and revved much more freely. I cant remember what the article said about the engines once they were stripped down, but i think there were no noticeable signs of extra wear on the ragged engines, and so they couldn't determine if the properly run-in engines would be more reliable or last longer. I think they suspected they would last longer though. Sean
I remember back on the late seventies the local Audi dealer used to recommend my father kept his new Audi 100s ABOVE 80mph to run them in - apparently that was the advice from Audi and the mechanics said the cars that had fast motorway use right from the start were noticeably quicker when they were traded back in one to two tears later. I have been told by some of the most reputabe engine tuners that it is preferable to vary the loads widely fromt he point of view of the bearings. Apparently it takes a while for the bearings to actually work harden so its best not to load them fully to begin with. Living in the North East I have been round the Nissan factory a couple of times. Always fascinating to me, particularly to see the engines being started up on the production line when instaled in the car for the first time and ten minutes later on the rolling road at the end of the production line. The 2 litre twin cams were being run flat out at 140mph on the rollers within ten minutes of being fired up for the first time, then wheel spun off the rolling road and out into the compound! So much for imagining grandad running his Nissan in - it had already done 140mph before going on the transporter to leave the factory!
Soft run-in times are a thing of the past, I think. I did a beetle (old aircooled, not faggot new type) engine today, the owner INSISTED that he had to have Total Seal rings. I hate those on a rebuild, they are a very hard ring to bed in. So I gave it a hone with the rough stones, and didn't bother with the finer ones. 10 minutes at 3000 to keep the cam happy, then I went out and drove it like an eejit. After a couple of overheats, let it cool down, thrash it again - it gives great compression, doesn't smoke at all, and REALLY pulls hard. And that's after probably about 10 miles...... (lol, I couldn't find reverse, so had to drive for ages to find somewhere big enough to swing round in!).
Aircooled nuts - he'll spend a fortune on a full-on engine, but doesn't want the gear linkage sorted. The engine cost him , but he doesn't want to spend 50 to have it shift gear properly...........
