My engine - help selecting a camshaft

[cds72911]

Okay, so I can't figure out what the profile of the SCRS cams are like. No biggy, I guess the real issue is how do I select the best cam for my particular engine, given my intended use.

My engine:
The engine is a '79 3.0 ROW (930/03). I am going to run Weber 40 IDA 3C carbs and SSI heat exchangers. I plan to get JE pistons with valve relief pockets and something like a 9.5:1 compression ratio. It will be a single plug setup with a MSD 6AL ignition. I'll gladly open up the ports on the engine if it makes sense.

The car:
The chassis is a '72 T with the addition of SC flares and fiberglass front and rear bumpers and decklid. The transmission is a magnesium '72 915 with a 7.31 final drive and stock gears. I'm running 6x15 (front) and 7x15 (rear) wheels.

Intended use:
Good weather + weekend driving and the occasional drivers education event. I'd like a broad torque curve, rather than a peaky high revving engine. I'd gladly sacrifice high end horsepower for drivability.

What cams would you recommend given that information?

Thank you.

[Early_S_Man]

Charlie,

Real simple ... GE-60.

Years ago, I plotted the profile of the early 'S' cams and the 906 racing cams on a 3' x 4' dry erase board, and it became quite evident that 'bigger' was an accurate description of the racing cam! It had more of everything ... duration, lift, and overlap! The 'S' cam profile fit completely under the 906 cam profile at every point!

As I posted on your other thread, the SC RS cam would fit very nicely on that old plot I did ... in between the 'S' and '906' curves ...

The GE-60 cam grind has about the same duration as the 'classic' 'S' cams, and more lift, so it will have better bottom and mid-range torque, and the top-end ferocity of the 'S' cams, too! Just check Matt Holcomb's latest thread about his 2.7 MFI engine with GE-60 cams!

[cds72911]

Thank you, thank you, thank you.

I really appreciate this advice.

Charlie

[Bill Douglas]

Charlie wazzup? It sounds a really interesting project. an early car with that sort of engine setup will really fly.

Bill '79SC

[CamB]

Whooops, wrote a big reply in the other thread.

I am more or less getting this. JE 9.5:1 pistons, early SC case/heads plus:

- 'S' cams (my research suggested GE-60 better though - as Warren says - but 'S' cams were on offer and MUCH cheaper for me)
- twin plug (again, already on offer - don't need it)
- MoTeC controlled EFI converted MFI stacks (on offer, and a damn sexy concept , but Webers will do the same job, just maybe not as smoothly at low revs)
- ported and polished heads (already done)

I am told this engine dynoed at 240+hp at the crank with minimal tuning of the MoTeC and plenty of scope to get more. I will be happy with anything over 250hp with a standard muffler, which is a pretty realistic target. I expect with the 'S' cams I will still have buckets of torque from low revs.

Bill,

The engine is in Christchurch and I will be having it installed there in March, so when I drive back through Wellington I will be sure to look you up.

[CamB]

Oh, and one more thing.

Just remember the car (tyres, suspension and brakes) was designed for <200hp (well, I guess the SC had about that and the Carrera more again on sort of the same brakes etc), so you may want to upgrade them too.

Cam

[RoninLB]

With all respect to every one, I heard that one of the Stoddard clic uses Solex with porting to get great street action, w/Webers, SSI, etc. This guy has a rep. for this set-up

[Bill Douglas]

Cam, excellent! I've got plenty of spare rooms at my house so stay over and we could do a few vineyards the next day. A bit of a drive though - 50 miles of windy roads

[cds72911]

Warren,

Again thanks. I'm trying to find contact info fro Jerry Woods and think I found a phone number that may work (I can't find him on the 'net).

Bill,

Yeah, it should be a real screamer. If the engine turns out okay it will have a nice power to weight ratio and that spells fun.

Cam,

Motec sounds cool - sounds like a good project. I'm going low-tech for simplicity sake (I write software for a living so the last thing I want to do on my free time is fiddle with a computer in my car). I'll be happy with whatever hp I get as long as it is drivable.

I think I'll pass on the twin plug setup, although trust me in my "sky's the limit" phase, I thought about it. If I did that I'd probably try the electromotive setup, but that stuff is too expensive for my blood (did I mention I'm trying to do this without going broke).

Yes, I've thought about the suspension issue. I think I am going to reasemble it all stock, perhaps with some bigger torsion bars, but that's it. I will tune it more once I see what it feels like. The car came with the 'S' option suspension (Konis, f/r swaybars and aluminum front brakes). I've had great luck with Bilsteins on other makes, so if I can find the right front housings I may convert to them eventually.

I suspect I'll want to upgrade the brakes eventually too, but I don't want to make that investment until I see what the stock setup feels like. The '73 Carerra RS had 210 hp and a very similar setup, so perhaps it will work OK as is.

As far as wheels and tires, I'm going with the same setup as the RS - front 6" and rear 7". I have a decent set of speed rated pirellis waiting to go on and will eventually upgrade those when my budget recovers. Unfortunately I have the "red-headed-stepchild" cookie cutter rims, so I'll be shunned by the mainstream Porsche crowd but they were a good deal and will suffice until I can find a nice set of fuchs.

Good luck with your project. We'll have to compare notes when we get them both together...

Thanks,
Charlie

[Early_S_Man]

Charlie,

Jerry Woods Enterprises ... Phone -- 408 369-9607

The last time I saw him list his GE cams they were $1098 per pair. Since the sport springs are generally recommended, that makes a pretty steep (around $1600) package!

If Web-Cam or Elgin can't do the GE-60 grind ... just go with an 'S' grind, as it will work just fine!