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Cobra Engineering secondary timing tensioner fix

66K views 115 replies 33 participants last post by  terminatorlou 
#1 · (Edited)
Finally thanks to Jameshell we have a affordable fixed secondary passenger side tensioner. Beware big pictures. The tensioner literally took a minute to swap over the parts. I will also show how easy it is to swap stuff. This takes around 4 degrees of timing error off the passenger side intake camshaft. James did such a great job even down keeping the oiling groove that oils the chain. The solid steel piece is top notch.





 
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#10 ·
Yes cost please. I would like to purchase this ASAP!!
 
#12 ·
yes that is what I read as well!
 
#13 ·
Didn't see the exact price on the other thread...

I recently did the cams on my car, did them myself, I installed FordGT cams, I bought & used the Ford cam tool kit, it has a key that fits into the back of the cams to lock them in the correct positions with all timing gears at a certain position, I did notice how all the slack still needed to be taken out of the longer timing chains as it appeared that if they were not totally tight while at the correct positions it would throw off the cams timing, but I never thought about there being any slack from cam to cam on the little chains between them...
Do you guys honestly think this new tensioner that James of Cobra engineering has made is gonna work that much better than a stock one?? Especially on a car with 15k miles on it... Not trying to take anything away from James, His parts look Awesome!

The original poster mentioned that the cams using a stock tensioner could be 4 degrees off... what is that info based on? And what does 4 degrees equate to in horsepower lose?
 
#14 · (Edited)
didn't see the exact price on the other thread...

I recently did the cams on my car, did them myself, i installed fordgt cams, i bought & used the ford cam tool kit, it has a key that fits into the back of the cams to lock them in the correct positions with all timing gears at a certain position, i did notice how all the slack still needed to be taken out of the longer timing chains as it appeared that if they were not totally tight while at the correct positions it would throw off the cams timing, but i never thought about there being any slack from cam to cam on the little chains between them...
Do you guys honestly think this new tensioner that james of cobra engineering has made is gonna work that much better than a stock one?? Especially on a car with 15k miles on it... Not trying to take anything away from james, his parts look awesome!

The original poster mentioned that the cams using a stock tensioner could be 4 degrees off... What is that info based on? And what does 4 degrees equate to in horsepower lose?
lets just say that when used it has shown 4-5 more mph through the 1/4 ACCORDING TO THE GOD OF MODULAR MOTORS-MIHOVETZ
 
#15 ·
If the cost is $100 what is there to really loose. When can we order it?
 
#17 ·
Sorry guys I have been slacking today.

Unfortunately I did the math and I will have to get $180 for this.
Having to make it out of steel is what killed me. I had to get new tooling and it took 3 times longer to run than aluminum.

Work is shutting down over Christmas and New Years. So I plan on running some of these off and making them available then.

Thanks for your patience.
 
#21 ·
James,

Any chance of an initial offering via group buy at a discounted rate via large volume @ once? :bigwink:
That would help. I am sure we could do something like that.

What's the difference from this and the one JM designed?
Honestly I don't know as I am not willing to buy one for $600 to look at. I developed this off of a stock Ford tensioner.
 
#22 ·
In a 2k hp 8k+ rpm application... John went on to say he felt there would be little if any noticeable gain on a typical 600hp 6500 rpm street type car.

I'd love to see a true before & after test done.
 
#23 ·
I would like one not for the MPH gain because that means ZERO to me but for the simple fact of keeping the cam timing correct! Put me on the LIST!
 
#27 · (Edited)
I think you are reading the tea leaves exactly correct, Joe. When Ford designed the passenger side tensioner they simply did it wrong! Someone looked at the driverside of the engine and saw the tensioner pushing downwards and he did the same for the passenger side (probably the same guy that 'engineered' the 4 thread sparkplug holes and the under cut radii on the crank snout among other little jewels). Therein lies the problem.

The primary drive on the driverside exhaust cam tensions the upper chain track and leaves the lower side track slack. Chain manufacturers (and good old common sense) tell you to pick up chain slack on the slack (good name for it) side of the chain. That is exactly what the driverside tensioner does.

On the passenger side, the primary drive is again on the exhaust cam but it is now left of the intake cam instead of right of the cam as it was on the driverside. When you position it to the left instead of the right of the intake cam, the tensioned side of the drive becomes the lower chain path and not the upper path as on the driverside. For reasons known only to Ford they chose to tension the same (and now incorrect) passenger side lower track of the secondary drive chain the same as they did on the driverside of the engine.

When the chain tensioner extends the tensioning shoe, the effect with the OEM tensioner is to advance the intake cam on the passenger side by many degrees. How many? It depends on how much slack your particular drive chains provide. Take a moment and visualize the two cams with a taught chain on the driven side track. Now take the taught chain and push it up or down (our OEM tensioner pushes down). When you do this the exhaust cam does not move, it is held inplace by the primary drive chain.

Instead, only the intake cam moves. The movement is in the direction of rotation, which means you are advancing the intake. How much? Again that depends on the available slack in your secondary drive chain. When most guys degree their cams they get super critical about getting the cam phasing correct to within a fraction of a crankshaft degree. That doesn't hurt anything - it also does not make a material difference in how the engine performs. if you get you cam phasing correct within a degree or so of your target number, whatever it may be, you are as good as you are ever going to get.

The big question that should pop up now is, if all that is true why are we making such a big deal out of this admittedly wrong tensioner design. The answer is it moves the intake cam waaaay more than 1˚ and it is not static. The cam positioning is continually changing based on what the tensioner is doing. The other reason this is a big deal is the chain manufacturers are specific about the correct and incorrect way to tension the chain. The difference between right and wrong from the chain manufacturer's perspective is longevity. FWIW, Ford chose to do it exactly wrong on the passenger side of the engine.

In the final analysis, we end up having two very good reasons to correct this oversight on the part of Ford Engineering. One is performance related and one is longevity related. Until James decided to make this product our options were few, far between and pricey. This is a huge step forward. I can not encourage you guys strongly enough to implement this upgrade. It is simply the right thing to do!

Ed
 
#28 ·
Perfect explanation Ed. As soon as it becomes available I'll be first on the list!!!!
 
#30 ·
Im in the process of a complete motor build so it is perfect timing for me!!!
 
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