Wide Lobe Cams

[Mike Horton]

Thanks, John!

... so based on this chart, do you believe it true, that the late 912 "616 105 102", & the " 616-105-105", have the same timing ?

[Jacques Lefriant]

CJ
on John's list the Neutek cams are the ones with different int/exhaust. The ro 200.5 and Neutek copy(SC-200) have the 104 LC. I would believe the lifts are correct for the cams shown but the durations may be off since these are lobe only and you will get different results if the indicator is working off a point or small radius roller or if the contact is made by a lifter. most of the cams i have done we try to use 105* LC. the list shows the N and C cams are different but we will have to wait till i confirm it.
j

[C J Murray]

Yes Jacques, the N and C are different for certain. They are about the same, a tick more duration for the N but a fair amount more lift for the C. The fact that the C had a higher rocker ratio means it had much higher intake valve lift and that the duration at the valve was even closer to that of the N.

[Jacques Lefriant]

CJ
now the question is what cam(NorC) would you recommend if you had the later valve train or should we we do a dual pattern with a C int and a N exh or the other way around and what is the best fit for the heads?
j
Dan
Porsche lists the lifter at $139.54ea the Web ones sometimes have the 2 grooves like factory and the Stoddard ones and most aftermarket ones have the single groove. I think Web will regrind your old lifters but it is not as convenient as new ones.
j

[C J Murray]

question is what cam(NorC) would you recommend if you had the later valve train

The C cam, hands down.

My Speedster has the C cam with iron rocker stands and 28mm Zeniths. It runs very well but falls off noticeably past 5000 rpm. I think the SC cam and iron rocker stands with 28mm carbs would be a better combination if you want the full 75 HP.

32 mm carbs need the SC cam and late style rockers.

[John Willhoit]

Mike,

The 1600 Super, Super 90, SC, and all 912s used the same camshaft.

[Vic Skirmants]

Mike,

The 1600 Super, Super 90, SC, and all 912s used the same camshaft.

That has been my understanding for 54 years.

[Mike Horton]

Thanks, John, and Vic, that has been my understanding, as well, as I tend to accept what is in the little factory spec book. Some advertisers, however, show a "912 Wide Lobe" cam, with about 10* more duration... I just wanted to confirm, while the "experienced" were watching this topic, which I appreciate, as early next year, I plan to finally go through my old original '68 912, and I'd rather do it right, once, than to do it over, I guess it's my aviation background. Thanks, to all who have offered knowledge, as this can be more foggy, than some items. I've had personal experience with the old narrow 102 super, and others, so most of the confusion, comes from "creative" marketing... I suspect.

[John Willhoit]

That wide lobe cam was the RO200,5 from Schleicher in Germany. It was called the Tricom cam in the US by some.

[DonCichocki]

Hi Jacques,
I made an adapter to fit inside the lifter bore that makes contact with the dial indicator. This should give me a good reading of duration and lift at the lobe while assembled in the case.
Regards,
Don

[Jacques Lefriant]

Hi Don
very good i will go back to Crower after the holidays an check several cams. they have at least 2 cam checkers and have replaceable lifters to use. in the software the cam checkers can compensate for rocker geometry they also calculate the foot which is the minimum lifter dia before it "hooks" catches the edge. checking 911 cams is very problematic due to the contribution of the cam tower.
j