Cam lobe exhaust lift high

[Alcyone]

Does any of this matter as I have hydraulic roller lifters?...
Checked the cam lobe lifts lifts from the top of the pushrods. Cam, lifters and pushrods are all factory still. Pretty good condition. Checking from the top of the pushrods, all the intake lobe measurements were okay (within 0.01mm of spec) but the exhaust lobe measurements were all high by in between 0.06mm and 0.10mm. I took at least 4 measurements each time to confirm this.

Cam Lobe Lift Specs: Exhaust 6.48mm / Intake 6.56mm
Piston 1: Ex 6.55mm / In 6.55mm
Piston 3: Ex 6.54mm / In 6.55mm
Piston 5: Ex 6.56mm / In 6.56mm
Piston 2: Ex 6.55mm / In 6.57mm
Piston 4: Ex 6.58mm / In 6.55mm
Piston 6: Ex 6.58mm / In 6.57mm

When the heads and block were at the shop, heads and block had a 5 thou shave I think they said (0.127mm x 2 = 0.254mm off each side). Also, the exhaust valve seats had to be redone as the valves had all sunk in.

Does this mean that I now add the 0.254mm (for head and block shave) and approx 0.10mm (over on the cam lobe exhaust lift) to be 0.354mm in total? Do I need to get new pushrods or is this okay as I have hydraulic roller lifters?

 

[Alcyone]

By new pushrods I mean shorter pushrods.

 

[harrop.senator]

Hey man sorry i only just saw this . If you havent found out yet what you need to do is check the rocker wipe. Colour in the valve stem tip with a permanent marker / sharpie.

Rotate motor twice undo rocker and the marks should be in the middle of the tip and itll leave a witness mark if its to far to the outside? I think if its to long . I've had cams reground on these n re used stock pushrods so you should be fine.




Its hard to tell the marker around it but the shiny bit in the middle is the contact patch. It doesnt have to be perfect as pushrod lengths are quite a gap its not in mm perfection if makes sense. It needs to be in the middle and i think its 5-10% each each way is tolerable.

 

[VR38]

How is your valve lash?

 

[Alcyone]

Hey man sorry i only just saw this . If you havent found out yet what you need to do is check the rocker wipe. Colour in the valve stem tip with a permanent marker / sharpie.

Rotate motor twice undo rocker and the marks should be in the middle of the tip and itll leave a witness mark if its to far to the outside? I think if its to long . I've had cams reground on these n re used stock pushrods so you should be fine.

Its hard to tell the marker around it but the shiny bit in the middle is the contact patch. It doesnt have to be perfect as pushrod lengths are quite a gap its not in mm perfection if makes sense. It needs to be in the middle and i think its 5-10% each each way is tolerable.

Hey stranger I saw this on Youtube and had planned on doing it after cranking/priming the engine/lifters with oil when it was all back in the car. I have already taken the lifters back apart and soaked them again though. Is that enough to do this test or do that have to be fully pumped up properly? Engine is still on stand so I might do it tomorrow.

 

[Alcyone]

How is your valve lash?

Being my first ever rebuild, I researched heaps and read that I didn't have to worry about lash or pre-load as these were hydraulic lifters - I just had to torque them down to spec. BTW I'm using MACE 23ft-lb (31Nm) re-usable rocker bolts. But in saying that about not worrying about lash or pre-load, I did play a fair bit before torquing them down. I got each piston to TDC after the intake lift on the compression stroke and did the pushrod wiggle until there was no lash left. I did this to make sure that the valves weren't open at all and that the lifters weren't sitting on one of the cam lobes. Think I got that bit right? I then torqued up to factory specs (15Nm + 90deg). I then checked the torque on it and it was only about 22/23Nm. I did feel that the recommended MACE 23ft-lb (31Nm) was a tad tight to start with but using hydraulic lifters, I thought maybe it was okay to go tight. Different bolts too. My main concern was with the exhaust lobe lift being higher than the intake lobe lift and also higher than spec.

Any thoughts on the much higher torque setting for these bolts? When I spoke to one of the chaps at MACE over the phone, he said to make sure I stuck to their recommended bolt torques.

EDIT: Oops I forgot - I also adjusted to zero lash so that the slack was out of the pushrods/lifters and then did a half turn. This only got the bolts to about 17/18Nm - well below what the MACE bolts recommend.

 

[harrop.senator]

Tights tight with those it doesnt adjust the lash by doing them up with these rockers. Its not a solid lifter situation so no adjustment through rocker nut. That recommended mace torque is the abilities to hold of the fastener. Most holden fasteners are weak and non reusable the mace will be an 8.8 or 10.9 equivalent so can handle more twist.

I check pushrod length on stand rotating by hand after soaking all the lifters then once cams run in i check the wipe again.

 

[VR38]

Setting lash, or pre load is VERY importanrt

 

[EYY]

Setting lash, or pre load is VERY importanrt

Not on a standard engine with a stock cam, heads and other valve train components. Never hurts to check though.

If fitting an aftermarket cam with a different base circle or considerable lift, or if you've shaved .040 off the heads, or changed rocker type/lifter type etc it becomes important.

Once you have rocker geometry set up (as harrop sen said above), then you need to work out your pushrod length to give the correct preload for a hydraulic lifter. Lash applies to solid cam and lifter configurations. To adjust the geometry, you can machine the base of the rocker pedestal, or add hardened washers under pedestals as required.

 

[Alcyone]

Tights tight with those it doesnt adjust the lash by doing them up with these rockers. Its not a solid lifter situation so no adjustment through rocker nut. That recommended mace torque is the abilities to hold of the fastener. Most holden fasteners are weak and non reusable the mace will be an 8.8 or 10.9 equivalent so can handle more twist.

I check pushrod length on stand rotating by hand after soaking all the lifters then once cams run in i check the wipe again.

Okay I'll do the sharpie test tomorrow and take some pics. That should definitely show if everything is sitting okay