Installing Cams - GE & GTE differences

[Scott]

I recently installed the camshafts in my head and noticed that the N/A instructions vary from the TT. With the N/A it says to rotate the cams 120 degrees before loosening and re-tightening certain caps. With the TT they are just installed straight without any of this re-torquing.

 

What is the reasoning behind this? I'm pretty sure Toyota wouldn't have missed out this step for no reason so really just looking for some insight as to why they vary ever so slightly.

 

Thanks

[David P]

A slight difference is that the N/A exhaust cam has the distributor to drive, what difference if any that makes though.

 

What does Mr T. say for VVTI?

[Ian C]

I've seen two versions of it in Toyota docco! One says to do the caps up progressively tighter in a certain order as you say, and that's on the TT as well. The other says to do up two caps tight then add the rest or something I'm glad it's not just me getting confused.

[Scott]

I've seen two versions of it in Toyota docco! One says to do the caps up progressively tighter in a certain order as you say, and that's on the TT as well. The other says to do up two caps tight then add the rest or something I'm glad it's not just me getting confused.

 

 

The one I followed said to put on caps 3 and 7 and uniformly tighten them until they are touching the head. I can't really see the reason for doing it that way but I followed the manual. From there it tells you to put the rest of the caps on and uniformly tighten them all down over several passes..... but as the other 2 are already holding the cam down this is virtually impossible as they are almost on the deck before you even get a nip on the thing. Once I had them getting a nip I loosened off 3 & 7 and then proceeded to tighten as per the manual using the sequential order.

 

Quite happy that they are OK but I was really surprised at how hard the cam is to turn once tightened down. That timing belt really does have it's work cut out doesn't it

 

I've got a set of feelers now so hopefully I'll get a chance to size the shims tomorrow.

[Chris Wilson]

It's to put less stress in the cam, which being chill cast iron will snap like a carrot if it's bent much at all. So they say to tighten caps nearest lobes that are actually opening valves, then the lobes with no valve spring load on are done next. I just take my time and tighten them all a half turn at a time, progressively.

[Scott]

It's to put less stress in the cam, which being chill cast iron will snap like a carrot if it's bent much at all. So they say to tighten caps nearest lobes that are actually opening valves, then the lobes with no valve spring load on are done next. I just take my time and tighten them all a half turn at a time, progressively.

 

 

Do you mean the whole 120 degree loosen/tighten proceedure or the progressive tightening? I understand why the caps are tightened a bit at a time, but I don't get the diffences in proceedure between N/A and TT.

 

If anything it would make more sense for me to follow the N/A proceedure as that would appear to take the stress out of the cam and help to make sure the pressure on it was even and not down to the cam being bowed.

[Scott]

It's to put less stress in the cam, which being chill cast iron will snap like a carrot if it's bent much at all. So they say to tighten caps nearest lobes that are actually opening valves, then the lobes with no valve spring load on are done next. I just take my time and tighten them all a half turn at a time, progressively.

 

 

Do you mean the whole 120 degree loosen/tighten proceedure or the progressive tightening? I understand why the caps are tightened a bit at a time, but I don't get the diffences in proceedure between N/A and TT.

 

If anything it would make more sense for me to follow the N/A proceedure as that would appear to take the stress out of the cam and help to make sure the pressure on it was even and not down to the cam being bowed.