rb25 Degreeing cams with hydraulic lifters?

[Desean Strickland]

How would i degree my cams on an rb25 hydraulic lifter head? lots of information online about degreeing cams on NEO or rb26 heads with solid lifters but cant find a definitive answer about hydraulic lifters. is the process just the same for both hydraulic and solid lifters on an rb (dial indicator on top of the lifter for measuring valve position) or do i have to mess with my lifter to make it solid for the degreeing process?

 

[r32-25t]

It’s the same as doing the others 

[GTSBoy]

You can lose information about timing at 50 thou, but the centrelines will still measure up correctly.

[Desean Strickland]

thanks guys 

[TurboTapin]

As per Kelford and other cam manufacturers, hydraulic lifters must never be used for degreeing cams. You will get false readings due to bleed down. 

You either need an aftermarket solid lifter or to modify an old hydraulic lifter for this task. 

[Desean Strickland]

3 hours ago, TurboTapin said:

As per Kelford and other cam manufacturers, hydraulic lifters must never be used for degreeing cams. You will get false readings due to bleed down. 

You either need an aftermarket solid lifter or to modify an old hydraulic lifter for this task. 

Alright well now I’m confused, some people saying yes and others saying no. How would I modify my hydraulic lifter? Iv already pulled them apart to clean them so I know how to do that but what would I change inside the lifter to make it solid? And how would that work with clearance between the lifter and the cam?

[GTSBoy]

You need to jam something inside it to stop it collapsing. A washer, a spacer, a something. Needs to stay up at the fully pumped up height.

I still say you can measure centrelines with a collapsed hydro lifter. Whatever max lift is will be max lift regardless of the state of the lifter.

[TurboTapin]

17 hours ago, Desean Strickland said:

Alright well now I’m confused, some people saying yes and others saying no. How would I modify my hydraulic lifter? Iv already pulled them apart to clean them so I know how to do that but what would I change inside the lifter to make it solid? And how would that work with clearance between the lifter and the cam?

Read this article in its entirety.

https://kelfordcams.com/sole-purpose-of-degreeing-your-cams?srsltid=AfmBOook1TDTA-n6_7S3mRSXD6-NROlytY3aV25ETGP7ns636p3rPJNw

[r32-25t]

As long as the bucket stays against the cam then it will measure up fine, the valve will close compared to a running engine but the bucket will stay against the cam lobe 

[Desean Strickland]

Does anyone know what the centreline should be for the vct intake cam? On my cam spec card it just says VARI and doesn’t actually tell me what the centreline should be. I had to adjust my exhaust cam gear by about 5 degrees advanced so I’m guessing I would have to adjust my intake as well? Current intake centreline is 119 deg. Iv already asked kelford and they won’t respond, It’s the 246-A 262 cams. 

thanks for the help guys 

[GTSBoy]

Hmm. You're probably best off working out what the lobe centreline or even the LSA is for the stock cams, with VCT OFF. That's bound to be out there somewhere. Then, work on the assumption that the Kelford centreline is probably the same, and wouldn't be more than a couple of degrees away, if it is different at all.

I'm very surprised that you needed to adjust the exhaust cam by 5° to get it on spec. That screams there's another problem somewhere. Anything from the belt being 1 tooth off (how many degrees is one tooth worth?) to simple user/measurement error on the degree wheel. I say this because Kelford, like most quality cam manufacturers these days, does a pretty good job of actually making the cams to spec, not relying on patching it up afterwards like we had to do back in the 80s.

[Desean Strickland]

5 hours ago, GTSBoy said:

Hmm. You're probably best off working out what the lobe centreline or even the LSA is for the stock cams, with VCT OFF. That's bound to be out there somewhere. Then, work on the assumption that the Kelford centreline is probably the same, and wouldn't be more than a couple of degrees away, if it is different at all.

I'm very surprised that you needed to adjust the exhaust cam by 5° to get it on spec. That screams there's another problem somewhere. Anything from the belt being 1 tooth off (how many degrees is one tooth worth?) to simple user/measurement error on the degree wheel. I say this because Kelford, like most quality cam manufacturers these days, does a pretty good job of actually making the cams to spec, not relying on patching it up afterwards like we had to do back in the 80s.

Good advice, I’ll try that. 
and yeah i thought 5 degrees was a lot as well. The gates T291RB timing belt that was recommended for this engine was kinda tight when installing it and with both cams inline with the timing marks, the belt teeth wouldn’t line up with the gear. So I just turned the whole exhaust cam gear like half a tooth so the belt would go on and then adjusted the cam back inline with the timing mark, so some of that 5 degrees is from that. The actual cam has probably only changed about 2-3 degrees if that makes any sense lol

also wouldn’t stuff like decking material from the block, head and different thickness of headgasket and the fact that it’s a rb30 bottom end affect the accuracy of the original timing marks? 

 

 

[MBS206]

17 minutes ago, Desean Strickland said:

 

also wouldn’t stuff like decking material from the block, head and different thickness of headgasket and the fact that it’s a rb30 bottom end affect the accuracy of the original timing marks? 

 

 

No.

The mark is with respect to the cam rotation. None of those things have altered it.

When stationary, the cam position stays in sync with the crank position. It doesn't matter if you moved the head 4 feet up. Hence, that mark needs to stay exactly where it is.