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Old 10-10-2010, 01:13 PM   #1
DSM_Outback
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Default SOHC EJ25: Which Years and Models Came With Two Metal Cam Gears?

Which Years and Models Came With Two Metal Cam Gears?
I have a set of EJ251 heads and one gear is metal and the passenger side is bakelight.
What year and model do I need to tell the stealership to get both metal gears?
Thanks.
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Old 10-10-2010, 03:46 PM   #2
BAN SUVS
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No idea- but the bakelite ones are durable enough. I wouldn't make any effort to switch it out personally.
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Old 10-10-2010, 08:37 PM   #3
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I'm building an SOHC headed hybrid with lots of other goodies that don't belong in NA powertrain, so I'd rather do it right once.
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Old 10-10-2010, 11:59 PM   #4
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You know that even the STi's come with some plastic gears on the non-dual-AVLS ones, right?

Just use the plastic one, that counts as doing it right.
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Old 10-11-2010, 01:01 AM   #5
BAN SUVS
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Yeah, there are a lot of little things that you want to pay attention to, but that particular part is fine.
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Old 10-11-2010, 08:58 AM   #6
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I would agree with this. The lighter plastic cam gear is not an area to seek upgrade from.....even with big lopey cams.

Jay
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Old 10-11-2010, 10:50 AM   #7
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All this being said... is there an advantage to using the bakelite gears? I realize the minor weight savings but how bout NVH when running cams?
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Old 10-11-2010, 11:06 AM   #8
grafton
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the early sohc 2.2's had 2 metal cam gears...
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Old 10-11-2010, 01:15 PM   #9
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Quote:
Originally Posted by watchdoc View Post
All this being said... is there an advantage to using the bakelite gears? I realize the minor weight savings but how bout NVH when running cams?
I figure that's why the OE did it.

I was a little worried running two crawford adjusters and some Delta 1500HLs
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Old 10-11-2010, 07:03 PM   #10
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The OE did it in an attempt to save a few engines when timing belts slip or in accidents. What happens is the gear shatters stopping the rotation of the timing belt, therby saving the valves. I've purchased more than one core engine with a popped timing belt and a broken cam gear that had no damage, so I think it works.
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Old 10-14-2010, 11:28 AM   #11
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Quote:
Originally Posted by Matt Monson View Post
The OE did it in an attempt to save a few engines when timing belts slip or in accidents. What happens is the gear shatters stopping the rotation of the timing belt, therby saving the valves. I've purchased more than one core engine with a popped timing belt and a broken cam gear that had no damage, so I think it works.
After an off into a good sized tree last season, our 2007 STi finished a stage and was limping back to service when oil pres dropped to 0. Shut her down and loaded up the trailer with our tails between our legs. Once I started tearing into it, I found the disintegrated RH Exh gear, and the belt resting on the round head casting behind it. Not a hint of internal damage. New belt, gear, cover, bumper, fender door hood, rad supports headlight.... back to the races.


At the time I was pretty upset that they would make a plastic piece of junk, but reading Monson's post, that actually make a good deal of sense from an engineering stand point.

Last edited by wmdoucette; 10-14-2010 at 11:36 AM.
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Old 06-09-2014, 08:08 PM   #12
bcl
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Hi,
I know an old thread, but I'm doing some searching today trying to find any posts that show a weakness with the exhaust timing gears made from bakelite . I know bakeilte is a very robust and widely used material.
I'm running a strengthened & rebuilt Cosworth 2.6L, 6466, and up to 450awkw @25lb, after a new build & tune last week. I have avcs on the inlet (controlled via vipec v88), and non avcs on the exhaust. Car is setup for time attack circuit racing.
The part was originally off my old 2 litre STi, that I was unaware that had been re-used in the engine build-up.
I've owned 4 wrx's spanning 17 years, and never come across a problem with this is part before.

Yesterday on startup at race day the part broke, which came as a complete and unexpected surprise.

Not sure if cause of failure is age, cold temps (near 0 Celsius), or high power level.
Pictures attached.










Dyno initial tuning runs low/high boost



I've spoken to a few guys on this: generally most just use adjustable metal cam gears, bypassing avcs. I find that inlet avcs allows good spool, and I can keep good top end.

So I will look at a metal replacement for the exhaust pulley… maybe an adjustable metal aftermarket type.

Any comments appreciated.
Brian
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Old 06-09-2014, 11:09 PM   #13
Subie-Lifer
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I've only see them break when cam is seized. Do your cams have scoring on the cam caps or cams?
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Old 06-10-2014, 02:51 AM   #14
bcl
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The problem only happened 2 days ago, and engine hasn't been checked or pulled apart yet.
Seizing would be an unusual event, but I can see that if a cam seized the bakelite would be the next weakest link. The engine had started, given a couple of thousand rpm to back off a car trailer, then a large backfire, cutout & would not start after that. So that does not sound like a cam seizure.
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