sohc/dohc

Author
Discussion

wedg1e

26,736 posts

233 months

Wednesday 15th October 2003
quotequote all
In the mists of time there were the Suzuki GS motorcycles. They had DOHC with 2 valves per cylinder. The along came the GSX range, which were DOHC with 4 valves per cylinder. But Suzuki kind of cheated, and used forked rockers, so the camshafts still only had the profiles for 8 valves. Each cam lobe operated a forked rocker which in turn moved two valves. Setting the clearances on such a beast PROPERLY takes a bit of thnking about, because you have to allow for the oil clearance on the rocker. If you stick your feeler gauge in, it tends to tilt the rocker arm over a fraction. Set the valve up, then go to the other one and you compound the error and end up with too little clearance. So you have to do both valves together...

Another cam problem that exists concerns the Jaguar straight-6: the cam is so long that with time, it twists along its length , screws up the valve timing and no amount of fiddling will make the engine run right.

Ian

Mr2Mike

20,143 posts

223 months

Wednesday 15th October 2003
quotequote all
wedg1e said:

z_chromozone said:
If it had 8 valves / cylinder I would have no hair left by now.

Z



EIGHT VALVES PER CYLINDER???!!! You been on the happy baccy?





I guess you didn't read my post further up the thread?

wedg1e

26,736 posts

233 months

Wednesday 15th October 2003
quotequote all
Mr2Mike said:

wedg1e said:


z_chromozone said:
If it had 8 valves / cylinder I would have no hair left by now.

Z




EIGHT VALVES PER CYLINDER???!!! You been on the happy baccy?






I guess you didn't read my post further up the thread?


Errr... ahem... yes I did, actually. Doh. I think I got it into my head that you were comparing an 8v VW engine with a 16v and were relieved that you had the 8v. Look, it was late, OK... err... gibber...

I remember that Honda (vaguely) - one of those 'let's-do-it-because-we-can' ideas, like the Z1300 and the various rotaries, none of which REALLY solved any problems or did anything better than has been done otherwise.

Ian

Mr2Mike

20,143 posts

223 months

Wednesday 15th October 2003
quotequote all
It was an (ultimately fruitless) attempt to make a four stroke engine that would keep up with the array of very quick 4 cylinder 2 strokes that the other manufacturers had.