DOHC question for all.

[thecarguy]

Im not really in import guy but I am a sucker for toyota trucks. But here is the question that came to me while in another thread. When did the DOHC system become common place. It may be confusing the way I worded it but think of it this way: Fuel Injection was avalible on early vettes, but did not become popular untill the 90's. When did the DOHC system come about? And another question, In the New OFF-ROAD magazine they have an atricle about the next generation of Powerstroke deseil's that will be coming out. In which they mention that they will be equipped with 4 valves per cylender yet still use only one cam in the block. How is this done? Are there just a lot more lobes on the cam or are there 2 rockers on each pushrod? But the one that makes sence to me is that there is a really wide rocker that is depressing on 2 valves. Some Input?

[dohc82]

1982 was the first year that the dohc was available in the M series engine.(supra) I think they fitted twin cams into race prepped M motors in the late 60s.

[Gearhead52]

Well in this case it wasn't the little Asian fellers that came up with the idea. They just made it work in a daily driver situation.

I think the DOHC idea was of european design back in the 30's but very expensive to produce. Some expensive touring cars had them. Not sure which...I may even be all wet on the years but it's close.

Ford introduced the DOHC V8 to Indy car racing in 63, I believe, and was outlawed a short time later. Was uncompetitive.....produced too much power........Was never in a daily driver in production that I'm aware of...but I'm not a Ford nut either.

4 valves and one cam means rocker shaft and a double tip. If memory serves me, most of the OHC 4 valve per engines were in line 6's and had cam followers and extra lobes. Mostly diesels in early years. Mack was the last diesel engine maker to change to 4 valves per. That was in the early 80's

The big drawback of the DOHC engines were, more parts...more opportunity for failure.....Our Asian friends made it work better.

Pontiac came out with their version of a SOHC in line 6 engine in production in 66, I believe. Good engine.....would kick your butt in a race if you weren't prepared.