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The mkiv Supra Owners Club

What are 'adjustable pulleys?' and do I want them?


Tannhauser

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I've just bought some 264 cams. I believe that I have grasped the basic idea about what cams do. I can also see why a different cam profile alters the engine's characteristics (e.g. power output)

 

I don't know, however, what 'adjustable pulleys' are and whether or not these are necessary to fully enjoy my cams. I remember posts about 'adjustable cam gears' - and Terry discovering that the stock adjustment was best - and wonder if the two things are related.

 

Feel free to chortle at my naivete whilst responding.

 

Ta

 

Cliff

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Hi Cliff,

 

Adjustable pullies, or verniers, or adjustable cam gears, whatever you want to call them, just allow minor/precise adjustment of the cam timing.

Normally you line up the cams with the timing marks on the engine and each tooth is about 5-7mm apart. Verniers allow you to adjust beyond the suggested positioning compromise set by the factory.

 

Does that make sense?

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Adjustable cam gears allow you to move the position of the cam in relation to the toothed wheel which is driven by the timing belt.

 

To facilitate this the cam gear is made in two parts bolted together through a slotted hole. Sometimes there is a vernier system with a set of holes in each part of the cam gear. There are different numbers of holes in each part enabling fine adjustment by matching different pairs of holes.

 

It's often referred to as "dialling in" the cams, perhaps because it usually involves using a dial gauge to measure the valve lift at a particular crankshaft position.

 

You might want dial in the cams in order to time the cam to exactly the specs given by the manufacturer, or to change the engine's power characteristics by adjusting the opening/closing points or overlap.

 

Google it, there's plenty of info out there.

 

EDIT

I type too slowly :)

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Google it, there's plenty of info out there.

 

Cheeky bugger! :D

 

OK, thanks for that, folks. I didn't realise that cam gears = adjustable pulleys. Probably because the words 'pulleys' and 'gears' conjure up different mental images. Blasted technical nomenclature.

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So if (in Cliff's example) you had purchased some 264 cams, is it absolutely necessary to purchase adjustable cam gears too? From the previous posts I assume they are not required unless fine tuning is needed

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So if (in Cliff's example) you had purchased some 264 cams, is it absolutely necessary to purchase adjustable cam gears too? From the previous posts I assume they are not required unless fine tuning is needed

 

Using my new found knowledge that pulleys = cam gears...

 

I remember reading a post about Terry S fiddling with the cam gears for ages, only to find that the stock settings were the best. So, no, as far as I can see they're not necessary. Good - saved me some money.

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Cheeky bugger! :D

 

OK, thanks for that, folks. I didn't realise that cam gears = adjustable pulleys. Probably because the words 'pulleys' and 'gears' conjure up different mental images. Blasted technical nomenclature.

 

What I meant was search for "dialling in" :D

 

Although I do try to be a cheeky bugger as well :)

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I remember reading a post about Terry S fiddling with the cam gears for ages, only to find that the stock settings were the best. So, no, as far as I can see they're not necessary. Good - saved me some money.

 

That sounds like good news for me too. :)

 

I'll give Terry a call to confirm before ordering anything!

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Guest Terry S

This was purely from experience with a 256/264 set up but it was done on a proper engine dyno. The stock settings gave the best compromise. Think Paul Whiffin discovered the same some years later.

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Can you, then, buy any lightweight non adjustable, stock set cam gears for those that want to lighten then valve train but don't want the risk of an adjustable gear slipping??

 

(Oh and if you must have adjustable ones, FWIW, avoid the the adjustable cam gears with only 3 screws to hold them together....go for the JUN ones with 5 screws for a more secure hold...these also feature a stock outer wheel so you can be sure of a good fit on the belt)

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Guest Terry S

I *think* JUN dont do them anymore, at least Dusty cant get them.

 

I also believe the new HKS ones use a steel outer now, instead of that aluminium piece of sh1t that took my belt out......

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I also believe the new HKS ones use a steel outer now, instead of that aluminium piece of sh1t that took my belt out......

 

 

Same thing happened on a Soarer in Australia.

 

At least he confirmed that the 1JZ is a non-interference design...... :)

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Guest Terry S
Same thing happened on a Soarer in Australia.

 

At least he confirmed that the 1JZ is a non-interference design...... :)

 

I am glad you said that, as everyone keeps saying mine was the only one. HKS Europe said it was my fault for leaving them uncovered, hence the reason they make them look so pretty, to ensure they are covered

:blahblah:

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What happens if you click on the "Archive through April 03, 2005" link at the top?

 

 

EDIT:

Might show as locked because you aren't registered / logged in?

 

Or do you mean "Closed: New threads not accepted on this page" at the top? That refers only to the first page which is linked to via "Archive through April 03, 2005". I can post to the second page of the thread.

 

Do you want me to ask Manny to get in touch with you? Or you could register and post yourself.

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Guest Terry S

Yep got it, withouht pictures

 

Sounds very similar, but I dont have the gears anymore, Leon kept them. The edges wore down and became very sharp, shearing teeth off the belt.

What happens if you click on the "Archive through April 03, 2005" link at the top?

 

 

EDIT:

Might show as locked because you aren't registered / logged in?

 

Or do you mean "Closed: New threads not accepted on this page" at the top? That refers only to the first page which is linked to via "Archive through April 03, 2005". I can post to the second page of the thread.

 

Do you want me to ask Manny to get in touch with you? Or you could register and post yourself.

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I've seen nothing about the steel pulleys in relation to the Soarer.

 

Looks as if Manny gave up on the HKS altogether. His car's spec sheet now says JUN pulleys

http://www.alsc.aus.as/scripts/discus/board-profile.pl?action=view_profile&profile=manny-MODERATOR

 

According to a post on that ALSC thread the Aussie HKS agent confirmed "that there are 100s in the same boat with the Nissan boys having the same issues in their engines. He blamed his lack of action on his supplier HKS USA refusing to consider the issue." If it was that much of a problem, you'd think they'd make sure the new version didn't wear.....

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Guest chiefvinso

I thought that aftermarket cam gears or pulleys or tuggeys or whatever were lighter than stock?

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I thought that aftermarket cam gears or pulleys or tuggeys or whatever were lighter than stock?

 

They are....but that doesn't mean they will be any good.

 

I would have thought the "best" solution to this would be, not that anyone makes them, Titanium non adjustable gear wheels using the stock sttings. But the cost to purchase/manufacture them would make them a pretty poor bangs per buck option!

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