Cam pulleys group buy, original and round tooth | FerrariChat

Cam pulleys group buy, original and round tooth

Discussion in '308/328' started by derekw, Mar 14, 2018.

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  1. derekw

    derekw Formula 3
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    #1 derekw, Mar 14, 2018
    I'm getting a few more cam pulleys made as there were more people who wanted them than the first order and I need a set for another engine I'm building. The supplier has agreed to do both the standard 30 tooth trapezoidal cam pulleys and some Gates GT2 36 tooth pulleys with matching 24 tooth lower pulleys. The GT2 patent has recently expired. They will have 10 holes for the regular dowel pins (5 at 25 degrees apart and 5 at 26 degrees apart.) They will also have 10mm holes for the eccentric pin/sleeve for anyone who wants to adjust them 9 cam degrees or 18 crank degrees. Price will be $350 or €250 for four cam pulleys, $85 or €60 for two lower pulleys. Not sure if we will have enough to get both colours but for now assume they'll be black. The pins/sleeves will be €30 for a set of 4 pairs.

    Email me if you want some derekrwhite at yahoodotcom and let me know which tooth type you want and if you want the adjustable pins/sleeves.
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  2. Brian A

    Brian A F1 Rookie

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    #2 Brian A, Mar 14, 2018
    I have nice solid metal factory pulleys in my car, but I really wish I had GT2 pulleys and belts instead. It would be so nice to be able to leave the belts without worry for 10 years rather than the shorter period of the stock belts. Performance on other marques has shown GT2 belts to be so much better.

    The reluctance I have of making the conversion is the “prototype” nature of the set-up for a 308. Changing the belts is more or less the limit of my technical skill; I can follow instructions, but quickly go beyond my depth when improvisation is needed. It just seems too complicated for me to undertake.

    So, the conservative side of me is really prone to stay with the status-quo, despite dreading next year’s timing belt service. I really do want GT2 belts though.
     
  3. derekw

    derekw Formula 3
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    #3 derekw, Mar 15, 2018
    Brian, You could probably stretch the belt change to well beyond 5 years as the stress concentrations on the round teeth are far lower. Nick's Forza suggests 9 years or 60k miles and they have been selling them for a long time. I just changed a 15 year old HTD belt on my new (old) daily driver and it still looked to be in good shape (though there could be invisible cracks forming at the cord/rubber interface.)
    I would probably change at 7 years as insurance given the hassle and expense of pulling the heads to change bent valves (or worse still if you have the old sodium-filled valves.) It's really not that hard and be sure to check the lower bearings for any play and check for leaks from the seals.
     
  4. Brian A

    Brian A F1 Rookie

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    #4 Brian A, Mar 15, 2018
    Interesting that Nick is recommending 9 years and you are recommending 7 years for the round tooth belts. I thought it would be longer than either of those. My Hondas (interference engines) go 100,000 miles between belt changes (our 2003 Pilot is currently at 230,000 miles) (2 belt changes) but I suppose the belts mile out before they time out. That would not be the case with my 308.

    I've changed my 308's timing belts myself in the past. Yeah, its not that hard, but man, is it a lot of labor. And I loathe disconnecting the a/c compressor again considering now nicely sealed the system is right now.
     
  5. derekw

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    #5 derekw, Mar 18, 2018
    Brian, I think the belt killers in this design are probably the tight radius on the drive pulleys (about 61mm for the GT2 24T design), the almost 90 degree "backwards" bend around the tensioner, and the very high temperatures these belts reach. Has anyone reading this had a round tooth belt on for more than 7 years? If several people have gone to 9 years or 60k miles I would probably risk it.
     
  6. derekw

    derekw Formula 3
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    #6 derekw, Mar 18, 2018
    Someone asked me by email about the timing adjustment. You can either use the 10 fixed holes with the dowel peg as per the original pulley which had five holes at 25 degrees. These pulleys have 5 more holes at 26 degrees to improve the fine tuning of the timing. If you want to be able to adjust the timing with the pulleys in place, you can use the optional eccentric sleeves/pins in the 10mm holes to get 9 degrees of adjustment (turn the pin with a screwdriver.) Since the two 10mm holes are 174 degrees from each other (not 180 degrees) you can choose which hole fits your cam and setup best.
     

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