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  #16 (permalink)  
Old 09-16-2011, 02:19 PM
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Quote:
Originally Posted by techinspector1
With a 9.8:1 static compression ratio, the motor will want a cam in the 216-218 range on the intake side. This is just a generality, but will help you to see what the motor wants. Here's a chart that I put together. Bear in mind that this is just to get an engine builder into the ballpark of choosing the correct grind......
http://www.crankshaftcoalition.com/w..._compatibility
Thanks ... interesting. So my aspirations to pull hard up to 6,000 are likely unrealistic. One reason I chose the 327 for the 911 was to have something operating nearer the rpm range of the 3.0l boxer I sold out of the car. However, I wanted to be able to use pump gas.
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  #17 (permalink)  
Old 09-16-2011, 02:20 PM
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Ahh, I see.
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  #18 (permalink)  
Old 09-16-2011, 02:36 PM
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Quote:
Originally Posted by itstorque
Thanks ... interesting. So my aspirations to pull hard up to 6,000 are likely unrealistic. One reason I chose the 327 for the 911 was to have something operating nearer the rpm range of the 3.0l boxer I sold out of the car. However, I wanted to be able to use pump gas.

Go with about 220 but run it on a wider LSA, about a 112, with about 8 degrees more exhaust duration, it'll give you a flat torque curve from about 2800rpm to 6000. It'll be down on peak torque but it'll hold it longer.
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Old 09-16-2011, 03:05 PM
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Quote:
Originally Posted by ap72
Go with about 220 but run it on a wider LSA, about a 112, with about 8 degrees more exhaust duration, it'll give you a flat torque curve from about 2800rpm to 6000. It'll be down on peak torque but it'll hold it longer.
I like flat torque curve
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  #20 (permalink)  
Old 09-16-2011, 09:16 PM
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Quote:
Originally Posted by itstorque
He's worried about the lifter travel in the wishbone retainers esp given my bastardized setup.
That would be "dog bone" retainers, but yes- that's the same thing I was wondering about, seeing as how the OEM hydraulic roller set up only allows the 0.354" lobe lift.

BTW, this is one example of where a higher ratio rocker arm would be beneficial. You will be able to add some lift to a milder cam- plus keep the base circle larger to aid in the retention of the lifters by the dog bones- by using a higher ratio rocker arm. This will allow you to have valve lift that would be unavailable to you if you had to use 1.5 rockers with a cam that had a smaller diameter base circle.
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  #21 (permalink)  
Old 09-17-2011, 07:46 AM
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I have used the GM Hot Cam in a ZZ4 350. ZZ4 heads are the L98 Corvette heads, 1.94/1.5. The heads will handle the .525 lift with the LT1 springs. Lobe lift is .328. I thought it was a great street cam, well matched to the L98 heads which don't flow a bunch. A slight lope at idle, would probably lope a bit more in a 327. Very torquey, pulled strong to 6k where it was all done. Would bounce off the rev limiter at 6200 easily. Machined on a billet core, not cast. Just sayin', I don't think you'd be unhappy with it at all. If you're just looking for sound throw a Mutha Thumper at it - jk! Sounds like an interesting beast you've created, keep us posted how it turns out.
BTW, I still have the new unused ZZ4 cam - 208i/221x @ .050, .474/.510 lift. lobe lift .34 - if you're interested. Should be sweet in a 327.
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  #22 (permalink)  
Old 09-24-2011, 11:54 AM
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Measured actual cam specs

I just measured the cam specs in the block (using .050 ref pt):
Intake is .297 (.472 w/1.6 rockers) 265* duration
Exhaust is .303 (.485) w/1.6 rockers) 268* duration.
LSA is 119.5*

I got some pics of the lifters and the dog bone retainer at base circle and peak lift, will upload later. Looks like there is @ 1/16" available space to add lift before the lifter shoulder impacts the dog bone (bumping it up). That's still (1/16*1.6) = .1") if I'm thinking about this correctly.

Opinions on the cam?
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  #23 (permalink)  
Old 09-24-2011, 12:57 PM
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Quote:
Originally Posted by itstorque
I just measured the cam specs in the block (using .050 ref pt):
Intake is .297 (.472 w/1.6 rockers) 265* duration
Exhaust is .303 (.485) w/1.6 rockers) 268* duration.
LSA is 119.5*

I got some pics of the lifters and the dog bone retainer at base circle and peak lift, will upload later. Looks like there is @ 1/16" available space to add lift before the lifter shoulder impacts the dog bone (bumping it up). That's still (1/16*1.6) = .1") if I'm thinking about this correctly.

Opinions on the cam?
That wide 119.5 LSA along w/265/268 duration @ 0.050" lift are suitable for a BIG cubic inch and/or boosted/race application.

If the duration is advertised and not @ 0.050", the LSA is still not what you want, but at least the cam would be usable on the street. Not optimum- usable.
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  #24 (permalink)  
Old 10-03-2011, 08:53 AM
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Cam change update ... bearing failure

(Maybe this should be a new thread, but since the same project I went ahead and put it here ... )

Well, the domino's are falling. I have removed the cam and sent it to Midway Performance in PA. He's pretty sure I measured it incorrectly and based on comments here he could well be right, I don't discount it. At any rate I'm going to go with a custom grind because the price is not much if any different than a std cam and I like the idea of getting something that an experienced cam guy devises with full knowledge of all the tech factors specific to my car.

SO ... I pulled the cam to send away, and check out the first journal bearing (see pic). That's weird isn't it? I forgot to take a pic of the cams bearing journal before boxing it up, but it was not damaged (yet).

What is the cause of this bearing damage??
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  #25 (permalink)  
Old 10-03-2011, 09:11 AM
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Quote:
Originally Posted by itstorque
What is the cause of this bearing damage??
When cam bearings are installed as the factory, the bore alignment is "corrected" by honing the bearings and not the block bores, so there is a chance the cam bore is a bit off. Check all the bearings to be sure it's only the one.

Some other causes are debris under the bearing, a bent cam, out of round cam journal, an incorrectly made bearing, too tight timing chain, excessive valve spring pressure, oil starvation/oil breakdown/loss of oil wedge (although the appearance doesn't look as though this was the problem).

If a replacement bearing doesn't cure it, the bearing will need to be clearanced to fit, either by align honing, or (gasp) hand finishing.
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Old 10-03-2011, 02:01 PM
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cam grinder recommendation

Got a recommendation for 224/236 @.050 with 110 lobe separation "4* advanced". Same as the comp cams 276. I don't know what the 4* advanced refers to.

I'm a little leary it's too much, but now I'm second guessing an experienced cam grinder (who I've explained everything I want to), based on participating in this forum. I said I wanted a hint of nastiness in the cam. I definitely don't want choppy, and if lopey, then not much. More like growly would be what I'm thinking of ... I sound like an idiot! I think he's pretty frustrated dealing with me, and I can feel for him. It's a '76 Porsche not a '67 Z28. I'm really wringing my hands over getting this right.
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  #27 (permalink)  
Old 10-03-2011, 02:12 PM
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Quote:
Originally Posted by itstorque
Got a recommendation for 224/236 @.050 with 110 lobe separation "4* advanced". Same as the comp cams 276. I don't know what the 4* advanced refers to.

I'm a little leary it's too much, but now I'm second guessing an experienced cam grinder (who I've explained everything I want to), based on participating in this forum. I said I wanted a hint of nastiness in the cam. I definitely don't want choppy, and if lopey, then not much. More like growly would be what I'm thinking of ... I sound like an idiot! I think he's pretty frustrated dealing with me, and I can feel for him. It's a '76 Porsche not a '67 Z28. I'm really wringing my hands over getting this right.
I think that's as big as I would go w/your 327, given your 'wants'. Is this a flat tappet or roller? What did you or they say regarding the stall speed?

When they say advanced 4 degrees, that means the cam will open the valves a bit sooner and close them also a bit sooner. This tends to bolster the bottom end of the power band. To do this you would use a multiple keyway timing set or use a bushing in the cam gear where the dowel pin locates it on the cam. The multi-keyway set-up is the easiest to use, IMO.
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Old 10-03-2011, 02:22 PM
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Hyd roller, manual trans.
He mentioned installing it "straight up" - that seems to imply the 4* will be ground in. I was not planning to replace my roller chain setup.
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  #29 (permalink)  
Old 10-03-2011, 02:28 PM
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Quote:
Originally Posted by itstorque
Hyd roller, manual trans.
He mentioned installing it "straight up" - that seems to imply the 4* will be ground in.
If that's what he said, then straight up it is, and you won't need to chance the timing set.
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  #30 (permalink)  
Old 10-03-2011, 09:43 PM
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The only advice I can give you is get it running and drive it to a Porsche gathering, it'll drive 'em nuts.
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