Update: Adjustable cam pulley

I think the entire bolt situation is being over analyzed a bit. Look at what is already out there an learn from what is obviously working.
To use the 360 as an example because I know it so well it just uses 3 blots in slots much like those. The bolts are 8mm thread with a 10mm flanged hex head and are torqued with blue locktite.

Simple, cheap, and convienent.

Otherwise it looks like a good design.

I like the vernier scale.

 

4 bolts (with shakeproof flared heads) actually, and they're only 6mm thread, loctited at 22 Nm...

But whose counting anyway.

The 360 design is very simple, which means reliable. (shame about the variators though!!)

 

Busted. You're right I described something else and called it a 360 but as you said "simple".

Simple is good. It doesn't need space shuttle hardware.

 

Just to clarify:
The cost is for a set of FOUR vernier marked and adjustable cam gears for the qv and 3.2.
Yes?

 

pulleys used on 308, 328, 208, 512BB, 365BB, 288, F40, Mondial 8 and QV and 3.2.

NOT 348 or Mond T.

 

Scott~

I really liked that first design with the vernier scale a lot better. If the 360 is using a simular design with four bolts, then 5 on this thing should be way overkill.

 

I have 2 comments.

The first is I like the second design better...I just don't like things that can move and planned to quietly stay with the OEM set-up, but you might sell me a set of the second design, if you added the vernier back on.

The second comment involves the vernier. The OEM set-up is 12 degrees per tooth, 25 degrees between pulley pins and 28 degrees between cam pins. All said and done, it lets you move the cam in 1 degree steps without running out of holes to put a pin in. Now, I don't know how careful ferrari was about where they drilled the holes in the cam, the pulley, or any of the lower drive parts at the crank end, but it doesn’t make any difference on their set up, a set of holes always lines-up. If they were careful about it, you’re all set. If they weren’t, when you’re new pulley with only 1 pin hole is installed, and the cam timing set to OEM specs, the position could read as much as 4 degrees on the vernier. Not the end of the world for sure, but a bit of a nuisance. You might want to add some more choices for mounting hole to the pulley to solve that problem….I’d suggests a minimum of 5 spaced 25 degrees apart.

 

Not a problem... you're not in the business of making/selling parts... you're creating something new for your own use and finding out if there's other interest. This kind of innovation and sharing is what FChat is all about, though we WOULD like to see you at least Silver Subscribed. Once this gets off the ground, of course, then you can't advertise here to keep on selling them ongoing without being a sponsor, though you could advertise them in FerrariAds as long as you're a subscribed member here.

 

I see what you're saying..the key is to know which hole should line up for say 6*. To, the advantage of an adjustable pulley set-up would be that I don't need to pop off the cam covers to change the cam timing an know I put them where I meant.

On most cars, without an adjustable pulley, it isn't possible make an adjustment, but that isn't true with a 3x8...you can set the cams any place you please using the factory parts. I would spend the money to be able to move the cams onthe dyno in 15 minutes vs 2 hours the OEM way....but I'd need to know for sure where I was moving the cam to.

I guess the way you have it, the go would be to time the cam and just mark the zero hole. Then if it's just a matter of counting holes, that would be fine....but if you tear the engine apart and mess with the timing cover, the zero point will move, and you'll have to re-mark the pulley...once there are 2 punch marks, it can get confusing.

I like the second set of holes idea.

another thought. You could open the ID of the pulley part so you can put a tool on the cam part to rotate it. That would make would make moving the cams really easy...loosen the bolts, pull the pin, roll the cam, pin it, tighten...all for cams done in 5 minutes....without trying to get a tool on the back side to roll the cam.

 

I still like the first design. Its simple and it would work just fine

 

Okay, I don't have a degree in engineering, but I have been around and ive seen some pretty wierd stuff. That string of holes going around the circumference looks like it would be a good place to get a crack started. Secondly, without a degree scale register like you had on the first design, short of taking a picture or marking it in some way, we would have no way to know where it is, or where zero would be if we wanted to move back to it. The first design gave us an easily readable scale, so that if we had the cams degreed to a factory standard, or wherever we wanted to have them set as a starting point, with the register centered, we would know where we were. If someone wanted to play with timing a lot, or lets say adjusting for weekend track use and back again for weekday street driving, that register would come in really handy.

 

I guess I dont see why it needs a pin at all. If the 360, as was pointed out earlier, has only four bolts, and no pin, your first design should work well as is. Also, unless its lined up perfectly, it could be difficult to thread that pin in without bunging up the threads. One last thought, also maybe overkill, what about steel nuts on the back side that the bolts thread into?

 

Now you see the problem with custom parts...everybody wants them custom and trying to find 2 that agree is pretty hard

You've found the heart of the problem in your question about which hole puts you at factory spec....and the answer is the all of them, depending how you may have assembled the gears in the timing cove and lower pully on it's shaft. Ferrari does not make any effort to ensure the lower parts are timed in any way, they do all the work on the upper pulley. No matter how the bottom is assembled, there will always be a combination of skipping belt teeth and moving the pin that will put the cam in proper time...once timed, the setting will stay the same with blet changes or even pulling the cams in and out...but if you touch the timing cover, there is no way to put it back together the way it came apart and the holes that are pinned will change on top to get the cam back in time.

I would be very very surprised if you ever found 2 engines that had all 4 pulleys pinned in the same place. That's why I suggested that there really is no getting around needing to time the cams when the pulleys are installed. If your pulleys have the same mounting at the OEM with multiple pin holes, you can get the zero position to be zero +/- 1*...I guess if you went with a spacing of 24.5* instead of 25* it would be +/-0.5*.

Once the pulley is timed to the cam with tthe zero as close as possible, the ability to make a quick adjustment and know where you went and how to go back without pulling the cam covers would be nice...the belt cover would have to come off to get at the pulley, but there would be no need for a degree wheel and dail indicator which would make dailing in the engine a lot faster.

question. Are you planning to put side plates on the pulleys to keep the belt in place?

I think your lastest version looks very neat...but I still like any of the versions with a pin much better. I've never had good luck with slotted anything staying put in use or even when trying to tighten the bolts.