STI Cam pulley's

[dynomatt]

Has anybody compared our cam pulleys with that of the STi's? I'm hoping somebody has to determine whether adjustable cam pulley's are available.

Thanks,
Matt

[Gizmotronicus]

I think its controlled electronically isn't it? I dunno how you would make that work.

[TomsSVX]

Matt, adjustable cam gears are not an option on the SVX. We have a single timing belt pulley for each side and behind the rocker covers you will find scissor gears that drive the intakes off of the spinning exhaust cams... Adjusting them would adjust both at the same time, which is probobly not what you want

Tom

[dynomatt]

Thanks guys.

Gizmo, I'm thinking the pre-vvt models.

Tom...appreciate that, but as we are decking the heads to raise the compression, we need the adjustability back to time each bank properly as the change in height will have affected the cam position. Because the cams are fixed due to the scissor gears, we've had to set the lobe centre lines as part of the cam making. There can still be some advantages of adjusting the timing though...it's reduced compared to single cam belts per cam, but there's still some potential gains there. We'll most probably make offset dowels to give us some adjustment.

They look good BTW!

Matt

[SilverSpear]

Bumpin it from the dead... I know...

But this is a technique I read about concerning the adjustment of scissor type cams. It can be adjusted on a degree basis through reworking the dowel pin or the sleeve in the sprocket.

Either making a smaller dowel pin and adjusting the sprocket or machine the sleeve a bit bigger (1mm max) in the direction needed.

Another method is to remove the dowel pins and set the sprocket to any desired position. Then remeasure the the timing for verification.

Hope these can be applied on the SVX cams. What do you guys think?

[TomsSVX]

Originally Posted by SilverSpear

Bumpin it from the dead... I know...

But this is a technique I read about concerning the adjustment of scissor type cams. It can be adjusted on a degree basis through reworking the dowel pin or the sleeve in the sprocket.

Either making a smaller dowel pin and adjusting the sprocket or machine the sleeve a bit bigger (1mm max) in the direction needed.

Another method is to remove the dowel pins and set the sprocket to any desired position. Then remeasure the the timing for verification.

Hope these can be applied on the SVX cams. What do you guys think?

Danny, our scissor gears cannot be tampered with or adjusted... They are held onto the cam with a snap ring and a spring washer... If you widened the dowel slot or used a smaller dowel, it would only leave slop. VVT is not going to happen with this engine unless you switch to totally different pulleys all around and work in some actuated pulleys.

Tom

[XT6Wagon]

Ford and others do use varible cam timing on thier SOHC setups (which is effectively how the SVX is given the gears connecting the cams).

However I don't see the trouble to try and retrofit a hydraulicly actuated cam gear is worth the small difference in performance. If it could be done at all without custom head castings.

There is a project for someone.... Billet heads done to the EJ207 design just in a 6cyl version. I'm betting there is HUGE power waiting in the heads given they are comparable to the very earliest WRX heads in design, and in the decade between them at the current STi heads they found 60 more hp, alot wider powerband, all while using a much smaller turbo.

[SilverSpear]

Originally Posted by TomsSVX

Danny, our scissor gears cannot be tampered with or adjusted... They are held onto the cam with a snap ring and a spring washer... If you widened the dowel slot or used a smaller dowel, it would only leave slop. VVT is not going to happen with this engine unless you switch to totally different pulleys all around and work in some actuated pulleys.

Tom

Tom I thought they were held to the cams by the spring and washer but they are locked with a pin. So I thought filling and readjusting the pin will do the trick.

[TomsSVX]

Originally Posted by SilverSpear

Tom I thought they were held to the cams by the spring and washer but they are locked with a pin. So I thought filling and readjusting the pin will do the trick.

Thats right, so if you slot the groove, it will just turn over and there goes your timing..

Variable cam are worth a lot quite honestly. If I were to do it, it would be a variable lobe which was changed by adjusting lateral position, this way you could effectively change duration and lift per the RPM.

Tom