924Board.org

[ideola]

We'll start with the pix:






Specifications:
Material: hard anodized aluminum
Weight: 1.6#
Settings: -3°, 0°, +3°

Introductory Pricing:
$245 + shipping
Available to 924board forum members ONLY. Expires midnight 31 May 2016. Pricing after 31 May will be $279 + shipping

10 units available at this time. Any potential for follow up runs will depend greatly on demand.

PM me with your email address for firm shipping quote and PayPal invoice.
_________________
erstwhile owner of just about every 924 variant ever made

[Tanso]

Oh no! I just ordered a adjustable cam gear and you have already sent me the weber package!

The gear looks very good and solid!
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Our 1983 Porsche 924 project: http://www.924board.org/viewtopic.php?p=364034#364034

[ideola]

Rationale for this design:
According to several folks I consulted, the 924 standard motor responds well to +10 degrees of cam timing. The 924 cam sprocket has 44 teeth, meaning that setting the timing belt "off" by one tooth can offer a way to advance or retard cam timing by 8.2 degrees. With a +/- 3 degree gear, you have the ability to set the cam timing as follows:

-11: gear at -3, belt 1 tooth retarded
-8: gear at 0, belt 1 tooth retarded
-5: gear at -3, belt 1 tooth advanced
-3: gear at -3, belt at TDC
0: gear and belt at TDC
+3: gear at +3, belt at TDC
+5: gear at +3, belt 1 tooth retarded
+8: gear at 0, belt 1 tooth advanced
+11: gear at +3, belt 1 tooth advanced

One of the designs we considered was slotted adjustments, and in fact, I provided a vintage sample gear that was so configured. A slotted setup allows for continuous adjustment, but the engineer we worked with was concerned about slippage. We felt that the range of adjustments described above provided adequate adjustability without the possibility of slippage on the gear, which could be catastrophic on an interference motor.
_________________
erstwhile owner of just about every 924 variant ever made

[uncledoodoo]

should the timing be advanced as well? Any good article on this tuning?

[ideola]

Here are the basics:
On a head that has been decked, even in a minor amount, "degreeing" the cam allows you to get the cam dialed in precisely for where you want peak power.

Bearing in mind, factory settings are for optimal balance of efficiency-power-reliability, there is opportunity on a performance build to eek out additional power and to fine tune where that power comes in with some simple cam timing tricks that the vernier pulley allows.

In general, advancing the cam timing will result in higher low-RPM torque, but will adversely affect high-RPM HP. Retarding the cam does the opposite: lowers low-RPM torque, but increases high-RPM HP.

So, for practical applications, you might wish to advance your cam timing for peppier street performance. For track applications, you might also want to be able to adjust timing (if rules allow) to put the power band where you want it depending on the venue. More advance is better for tighter lower speed tracks where torque is more important than high-end HP; retarding the timing is better for bigger tracks with long straights where top-end HP is paramount.

There's no way to give a % of power increase because there are way too many variables to take into account. The ideal way to use this as a tuning tool is to put in some dyno time and see how the different settings affect power output.

On a hot street application, just advance the +3 degrees and enjoy a bit more punch on your around-town driving.

{EDIT}
Here's a pretty good article on cam timing 101:
http://www.hotrod.com/how-to/engine/ctrp-0805-camshaft-timing/
_________________
erstwhile owner of just about every 924 variant ever made

[morghen]

So this is what you've been up to.
Nice product, will buy one or two when the time comes.
_________________
https://www.the924.com

[oharris]

I like it! Very cool design.
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'80 931

[JjyKs]

Damn i like the design.

Do you still have these and do you ship to Finland?

[ideola]

[JjyKs]