20V BT and ST Cam wheel differences?

[matt dunn]

Ok,

I have a few BT and ST heads and some TODA adjustable cams wheels.

The Toda were bought to suit a silvertop,
But I want to use them on a blacktop.

Reading through posts on here peole have siad that to use Blacktop cam you need blacktop cam wheels,
which would imply that the cam wheels are different.


So I have had a play with my spare engine on the stand
and cannot find any difference other than the actual width of the cambelt surface.

I did the exhaust first as it was the easiest.
I lined up all the cam timing marks to TDC as they are meant to be,
and lined up the dist sensor to mark the cam at TDC.
Swapped from the BT cam wheel which suited the cam/engine assy,
and fitted the ST camwheel.

Rotated until the camwheel marks lined up
and checked that the cam ended up in the same position by looking at the dist sensor,
and it is in exact same position,
This makes me believe the exhaust cam wheels are interchangable.

I then did similar with the intake.
lined the camwheel marks up again,
and this time locked the camshaft in place with a big crescent on the end opposite to the camwheel.
Had it held there by my helper and swapped the camwheel from the BT to the ST one, and rechecked the marks.

Once again all appeared to line up correctly.

So question is are the camwheels actually different or not??

[thegreatestben]

have a look at part numbers on toyodiy.com
edit:
Yup different part numbers.

[Mr Revhead]

the vvt pulley move different amounts don't they?

[matt dunn]

the vvt pulley move different amounts don't they?

Not according to spec's I found no.

Cam Timings - (AE101)Inlet Cam
IVO IVC
VVT <4400rpm 0° 70°
VVT >4400rpm 30° 40°

Cam Timings - (AE11)Inlet Cam
IVO IVC
VVT <4400rpm 5° 65°
VVT >4400rpm 35° 35°


So there is supposedly 5° difference in timing, but the same 30° of travel.

[sergei]

the vvt pulley move different amounts don't they?

Not according to spec's I found no.

Cam Timings - (AE101)Inlet Cam
IVO IVC
VVT <4400rpm 0° 70°
VVT >4400rpm 30° 40°

Cam Timings - (AE11)Inlet Cam
IVO IVC
VVT <4400rpm 5° 65°
VVT >4400rpm 35° 35°


So there is supposedly 5° difference in timing, but the same 30° of travel.

That spec assumes that VVT "kicks" in at 4400rpm which is bullshit.
VVT kicks in on demand (load based) on both silver top and black top.

Here what is actually different about ST vs BT cams:

They have locating pins for pulleys in different places, so if you use BT cam in ST you will also need BT pulley, or if you use ST pulley on BT cam, you will need to account for timing marks being off on the wheels.

The BT cams have cutouts in the lobes (lobes are narrower at peaks by ~ 1/3) while ST cam is normal looking cam.

The BT has slightly higher lift (supposedly).
Other than that they are same.

[matt dunn]

Here what is actually different about ST vs BT cams:

They have locating pins for pulleys in different places, so if you use BT cam in ST you will also need BT pulley, or if you use ST pulley on BT cam, you will need to account for timing marks being off on the wheels.

The BT cams have cutouts in the lobes (lobes are narrower at peaks by ~ 1/3) while ST cam is normal looking cam.

The BT has slightly higher lift (supposedly).
Other than that they are same.

4400 rpm aside it makes no difference, maybe it should just be VVT on and VVToff,

And if the locating pins are in different places how come when I lock the cam into TDC position and swap pulley the marks on the pulley's end up in the same place.

I know the EXH one are identical as I can lay them on top of each other and the dowell pin and the timing mark line up,
but you cant se through the Intake one to confirm but it appears the same.

Yes the lift is different on the Intake, 7.67 against the BT at 8.2,
where the exhausts list the same lift and timing,
and the cutouts are obvious once you've seen them,
but not concerned about those factors, just out to confirm for sure if the pulley's are interchangable or not, as I like to prove things rather than accept internet advice as gospel,

as internet advice says my engine that has been going for two years should have self destructed on it's first run.

[sergei]

Here what is actually different about ST vs BT cams:

They have locating pins for pulleys in different places, so if you use BT cam in ST you will also need BT pulley, or if you use ST pulley on BT cam, you will need to account for timing marks being off on the wheels.

The BT cams have cutouts in the lobes (lobes are narrower at peaks by ~ 1/3) while ST cam is normal looking cam.

The BT has slightly higher lift (supposedly).
Other than that they are same.

4400 rpm aside it makes no difference, maybe it should just be VVT on and VVToff,

And if the locating pins are in different places how come when I lock the cam into TDC position and swap pulley the marks on the pulley's end up in the same place.

I know the EXH one are identical as I can lay them on top of each other and the dowell pin and the timing mark line up,
but you cant se through the Intake one to confirm but it appears the same.

This is very interesting.
I should have tried this when I had a chance.
What it means, that there is no major difference in between them at all.
Apart from anecdotal evidence of lift being higher, and anecdotal 5 degree difference in timing.

[matt dunn]

This is very interesting.
I should have tried this when I had a chance.
What it means, that there is no major difference in between them at all.
Apart from anecdotal evidence of lift being higher, and anecdotal 5 degree difference in timing.

Yeah try before you believe,

The 5 degree's of timing difference,
I think everyone always assumed it was in the pulley difference's
but it may be in the actual cam itself which would mean the pulley's do interchange.

[matt dunn]

The only thing that bugs me at the moment is why TODA have different part numbers for the ST and BT adjustable cam wheels?

Is it as simple as the different belt width as there is about 3-4 mm difference in cam pulley widths on std wheels.

[85AW20v]

And isn't there a difference in belt teeth between ST and BT - by 1 tooth? If correct, what would be the reason for that?

[matt dunn]

And isn't there a difference in belt teeth between ST and BT - by 1 tooth? If correct, what would be the reason for that?

that is because the BT's hydraulic tensoner is in a slighlty different location to the ST's mechanical tensioner.
Been through that, and the crank drive pulley is different too,
but that's only the location of the timing mark on it.

[AceSniper]

the vvt pulleys dont swap over... I made one with some force... bolting it down but was a %##@ to take back off...
The toda gear may have slightly bigger hole or more 0 shape rather than o

The pin in the can is very slightly offset more from the center than the other I think

Also think its the dowel on the cam thats located 5deg diffrent from st-bt timing, as toda sell a offset dowel to correct it when using their cams as they are silvertop castings and when installing in a blacktop with std pulleys you need this pin.....

Thats how I understand it....

[frost]

the vvt pulleys dont swap over... I made one with some force... bolting it down but was a %##@ to take back off...
The toda gear may have slightly bigger hole or more 0 shape rather than o

The pin in the can is very slightly offset more from the center than the other I think

Also think its the dowel on the cam thats located 5deg diffrent from st-bt timing, as toda sell a offset dowel to correct it when using their cams as they are silvertop castings and when installing in a blacktop with std pulleys you need this pin.....

Thats how I understand it....

do you have this dowel to measure?
i would like to make one then spend $35 on it,
i see its only a step on it so should be easy to make, but that also begs the question of how it would sit in the larger hole if it has the step down in it, would it move around,
http://www.toda-racing.jp/en/product/cam/4ag5v-1.html

[matt dunn]

the vvt pulleys dont swap over... I made one with some force... bolting it down but was a %##@ to take back off...
The toda gear may have slightly bigger hole or more 0 shape rather than o

The pin in the can is very slightly offset more from the center than the other I think

Also think its the dowel on the cam thats located 5deg diffrent from st-bt timing, as toda sell a offset dowel to correct it when using their cams as they are silvertop castings and when installing in a blacktop with std pulleys you need this pin.....

Thats how I understand it....

Wierd as I can swap BT and ST pulleys onto the BT cams in the engine by hand with no force, and they all line up.

Reading from that site
http://www.toda-racing.jp/en/product/cam/4ag5v-1.html

The BT requires the cam to be advanced by 5 deg more than the ST does,
so to use the same cam designed for a ST on a BT, you need the dowell pin on the cam to be different,

which would support the fact that the timing difference is in the cam more than the pulleys?

[frost]

yes that seems to be the way i read it, i got toda cams and need that dowel,
but at $35 + post its a bit silly for a 12mm peace of metal,

[AceSniper]

I don't have one... it would be half tooth shift

I think the timing change is in the cam also, It could be just the gears iv tried but what iv had the dowel wont just slip in its very close though as the bolt will pull it down and not leave marks but jams up when I tried

[matt dunn]

yes that seems to be the way i read it, i got toda cams and need that dowel,
but at $35 + post its a bit silly for a 12mm peace of metal,

What are you using for camwheels?

[frost]

vvt on intake and adjustable on exhaust, the dowel only applys to the vvt cam wheel.

[AE25]

not sure what all this dowel sizing thing is about. i compared ST to BT and the teeth and locating holes lined up by eye.
i wanted to get rid of my vvt pulley rattle.. grabbed some BT pullies from pickapart, put em on the ST engine no problems. power feels the same. ran same ST belt and cams.. only change was top cam pullies. i lined up the crank pulley to TDC (didn't bother taking cam covers off either). then lined up the cam pulley marks to the notches in backing plate. all lined up (by the eye anyway). leave exhaust pulley to last, put belt on pulley then slip pulley on the cam.. don't need to remove lower belt covers. seems to work fine. should really retension the belt but meh... pullies same diameter i figured tension not need adjustment. 1/2 hr job.

[frost]

the dowel is for using silvertop toda cams in a blacktop head with blacktop cam wheels. because toda only make silvertop cams