rb25det kelford cams

Hi All

I'm at the beginning of an engine rebuild (ringland failure).

I have a lot of parts purchased including Kelford 262/272 Degrees advertised duration, 10.00mm/10.00mm lift and springs to suit.

These retain the hydraulic lifters

Now my question is ,has anyone just cleaned and reused the original lifters with any success or should i just shell out for 24 new ones?

Any problems with breaking in the cam? Thanks.

Hi Damien it is super common to just reuse the std lifters

no issues at all

Regards Ross Honnor

Hi Ross

Great! I will reuse them then.

Thanks for the reply.

Modern manufacturing is a lot better than it used to be - and they're normally very well lubricated with a direct feed - but, IMO, it's a bad practice to use used cam followers, in any engine, unless they're being refitted to the cam lobe they were on*. While you may get away with it most of the time, especially with mild camshafts, because of the wear patterns that may form or, worse, cupping, the new lobes may be loaded unevenly and so suffer some initial wear.

If there are any wear rings, lines or ANY sign of a concave face, I would very strongly recommend a new one be used instead, for that follower, at least.

You may want to check your documentation that came with the camshafts, or check with Kelford, as most camshafts won't be covered if used with old followers. Ah, from their web site "WARNING: NEW LIFTERS MUST BE INSTALLED WITH YOUR NEW CAMSHAFT" - source, https://www.kelfordcams.com/nz/technical-advice/kelford-cams-flat-tappet-camshaft-break-in-procedure/ - bucket type followers are a type of flat tappet.

*The exception being roller type followers, provided they're clean, checked for flaws, and rotate freely.

Hi Gord

Thanks for the reply.

I did indeed see the advice on Kelford's site but i wanted to find out the thoughts of people here as it seems to be a very divided topic.

There seems to be no scoring on the lifter face and I can check the face for concavity with a dial gauge, but between that, disassembly, cleaning, quick face clean/polish on the lathe and reassembly x24 new lifters are very enticing both time wise and for reliability as i was on the fence anyway.

I suppose the extra lift and stiffer spring compounds the problem and is having me favoring new lifters.

On the heavier spring topic Kelford recommend the use of a lighter break in spring.

Whats the opinion on using the standard spring for this or is there a chance that it might not compress enough?

My thoughts, and I may be mistaken, so get several opinions and, preferable, those of folks doing this very thing.

The problem with some flat tappet (non-roller) followers is a lack of lubrication during the critical 'bedding in' process when loads are high. It's more a problem with pushrod engines because most (all?) of them rely on the assembly lube and simple splash lubrication from oil thrown from the crankshaft and draining oil from the top of the engine.

Using lighter 'break in' springs reduce the loads and chance of the oil film failing between high points - this can be a huge problem with high lift/high rpm camshafts as the 'over the nose' loadings can be very high. Most heavier duty springs have 2, or 3, separate springs and it's common to use the inner/middle one for initial bedding in before installing the full spring assembly.

In your case, the engine has direct oiling to the lobe-follower interface and modern materials and techniques are greatly superior to the 'old days', but if you're OK with the additional time and hassle, it's still a sound idea to use lighter springs for this critical stage. With mild camshafts, like yours, I may not bother, TBH, but with more extreme I would take the time.

You asked about using the OEM springs, this may be an option, or maybe just the outer - BUT you MUST check you have enough compression available to avoid coil bind as that will cause an immediate failure of components - normally a minimum of 40 thou' between coils at full lift is acceptable, with more being better. I assume you've checked the spring installed spec'and actual installed heights? It makes a big differents to seat pressure (force?). Use a vice with soft jaws to compress the OEM spring to installed height, then add the cam' lift, to check the coil clearance.

I don't mind fitting the valve springs twice if as you say reduces the chance of the oil failing between the two surfaces. The Kelford valve springs i got are a single spring install .

Yes i will check the installed spec vs actual height then check the oem spring for coil bind at that extra lift.

If the oem spring doesn't suit i think i will just go with the kelfords for first start up the Driven break in lube Kelford provided.

Thanks for the advice .