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> Really cool valve adjustment system
sixnotfour
post Oct 9 2019, 06:28 PM
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race rocker and lash caps,,if youre really concerned...I doubt it..
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SNAPGAP
post Oct 10 2019, 07:04 PM
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QUOTE(djway @ Oct 9 2019, 06:22 PM) *

What is the weight difference between the adjuster assembly versus the steel nut?



The OEM jam nut weighs 2.7 g. The SNAPGAP collar, shim and cap head screw total 6.1 g. In developing SNAPGAP, I read a lot of articles about the impact of increased weight on valve train components. I am sure others with more knowledge than I can provide additional or more technical input. However, this is what I have taken away from my reading. Most of the articles concern the desire to reduce weight in valve train components in drag racing engines where a premium is placed on reducing moment of inertia on push rod engines where the rockers are directly opposed to gravity so as to achieve higher RPMs faster. Those engine builders are trying to balance the strength of components at 10,000 RPM vs. weight of rockers, valves and valve springs and push rod components vs. cost of titanium materials and so on. One article noted that at 5000 RPM additional valve train weight makes no meaningful difference.

I could not find any information on the 911 set up where the shaft mounted rocker arm ends are not directly fighting gravity.

In my personal experience driving my SC with and without SNAPGAP, I have not noticed any reduction in power or ramp up -- but I may be biased. Rather, my engine seems smooth, powerful and quiet -- no ticking.

I explored and had prototypes made of high strength aluminum (1/2 weight of steel) as an alternative to steel for the collars but at this point have concluded that because the expansion rate of aluminum is 2x that of steel, there is too much risk of the collar expanding and loosening around the adjustment screw. If I were convinced that eliminating the additional weight would make a meaningful difference, I would explore other lightweight materials such as Titanium -- but the cost may be prohibitive.

Hope that is useful information.

Brad
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SNAPGAP
post Oct 10 2019, 07:12 PM
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QUOTE(914forme @ Oct 9 2019, 06:26 PM) *

I would think that a logical step would be to offer it in Ti, just for the people who think they need it. You can offer both systems and be fine for us normal people who do not care. But for those who do, then Ti would be a logical choice.

After all lots of people with deeper pockets than I change over to Ti parts. Maybe when I retire I might start machining my own Ti parts. Most likely smelted from all the Apple cards my friends seem to be collecting. (IMG:style_emoticons/default/confused24.gif)



Some thoughts from a 911 owner:

"I too am interested in the tool, but I would prefer a set in a metal having similar characteristics to the stock metal. After several exchanges with Brad, he has indicated that Titanium would be a close match, but that the kit price would be higher, $325 vs. the current price of $175. The collars and screws would both be titanium. The weight reduction would be to knock the current SNAPGAP weight of 6.1 g down to 3.35 g vs. the OEM nut of 2.7 g. Otherwise the kit would be the same -- and, of course additional sets of shims would remain the same for both kits. The expansion coefficient for titanium is actually a bit less than steel, so the titanium collars would actually grip the steel adjustment screws a bit tighter than the steel collars when the two are heated by engine operation. "

However, after further evaluation, unless someone can provide me with a demonstrable benefit of reducing this weight this tiny amount on a 911 or 914 set up, I do not believe I will be offering the Titanium option. A respected engine builder told me that given the geometry of the Porsche valve train, this reduction would make no difference in performance. If it did, you would think Porsche would put the cast rocker arms on a diet. Hell, I can remove a few grams in a few minutes with my angle grinder. (IMG:style_emoticons/default/evilgrin.gif)

Brad -- from SNAPGAP
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djway
post Oct 10 2019, 09:30 PM
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How well does the wrench clear the suspension mount?
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914dave
post Oct 11 2019, 04:16 AM
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I have my set sitting on the shelf waiting for The next adjustment. I may actually be able to do the valves with the engine in.
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914dave
post Oct 11 2019, 04:16 AM
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Double post
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SNAPGAP
post Oct 11 2019, 08:41 AM
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QUOTE(914dave @ Oct 11 2019, 04:16 AM) *

I have my set sitting on the shelf waiting for The next adjustment. I may actually be able to do the valves with the engine in.



For spaces where the T-handled wrench does not fit without removal of components (or dropping the engine), you can use a 1/4 drive to tighten the small cap screw and a standard torque wrench set to 10Nm to do the torquing with whatever extensions you need. I know that my '78SC is not a 914 set up, but here are some pics of me working around the CAT on the left exhaust bank.

Attached Image Attached Image
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bandjoey
post Oct 11 2019, 06:10 PM
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when I see this performed on a 914 with heat exchangers I'll get the kit. I have a hard enough time with the shim method and don't see this working on a typw 4 In the Car.
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Morrie
post Oct 12 2019, 11:49 AM
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QUOTE(bandjoey @ Oct 11 2019, 07:10 PM) *

when I see this performed on a 914 with heat exchangers I'll get the kit. I have a hard enough time with the shim method and don't see this working on a typw 4 In the Car.


(IMG:style_emoticons/default/agree.gif)
I am in the same boat here
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