What has happened to my lifters?

[ukkid35]

It looks like it's been etched, but I can't feel anything with my fingernail

Most have some degree of marking, but this one is probably the worst

The engine has only been run on about ten days over the last year, the last time was over four months ago

[ukkid35]

There's no sign of anything similar on other parts

[ukkid35]

The engine suffered oil pump failure on idle with no load, which is why it is coming apart

However, there is no sign of damage to any of the cam caps or cams, and although the lifter wells had drained, they were not dry

[ukkid35]

stevieturbo said:

and the history of the cams and lifters ?

New, used, other ?

Cams are original, afaik

Original lifters were replaced with used perhaps 20k ago

Last time I saw them was about 2k ago, and there were no marks then

All surfaces were covered in oil, but they weren't bathed and partially submerged

[ukkid35]

Auntieroll said:

Other causes can be excess stress caused by over strong/coil bound valve springs,

New standard valve springs were fitted 2k miles ago, however the std cams are aggressive with 0.5" lift

The valve seats were recut so I also shimmed the springs which may have increased spring pressure slightly overall

I don't really have the funds for a new set of lifters right now, and they would be relatively easy to replace later if my position improves, so is there any significant risk if I leave them be?

[ukkid35]

Auntieroll said:

Continuing to run the engine with the followers deteriorating will be OK but.....,
The tiny shards of hardened steel will be carried round the engine in the oil
and will definitely NOT improve the overall condition of the rest of the internals !

Thanks, hard to argue with that

Perhaps you could help identify what engine they are from originally - They are 42mm diameter, 27mm height and weigh 74g

FWIW the camshafts would cost £600 and the lifter set would be £350

[ukkid35]

stevieturbo said:

spitfire4v8 said:

Seeing as al melling had a history with jaguar, and this looks very similar to the ajp follower, I would be investigating the jag route ?

https://www.ebay.co.uk/itm/172180905482

Their quoted 1.625" as an oversize...is still smaller than the 42mm mentioned in this thread. 42mm seems a pretty big follower.

They certainly are similar, but the standard diameter appears to be 1.5" or 38.1mm

https://www.scparts.co.uk/sc_en/cam-follower-1-231...

[ukkid35]

stevieturbo said:

So is it normal for your engine to have these lifters ? Or has someone modified it for them ?

generally they are fairly small, as they're for small 4v per cylinder heads, so springs etc tend to be small.

I don't have the skillset to modify any engine in any way (other than grenading the whole thing)

But presumably you need wide lifters for high lift cams - 0.5"

The AJP8 was designed to be exceptionally light, hence SOHC and Flat Plane Crank

Resulting in 121kg for 4.5L, is there a lighter engine weight/capacity ratio?

Edited by ukkid35 on Thursday 28th November 22:59

[ukkid35]

spitfire4v8 said:

there is a square pattern to the centre suggesting it tends to run in one position more of the time

That is where the cam lobe was resting for several months while the engine was left

All the lifters have a similar pattern, but the size of the square section is much less when the only the cam tip was touching the lifter

That is why I think the discolouration occurred when the engine was untouched for months

[ukkid35]

227bhp said:

Are you sure they aren't 41.2 diameter?

Yup




Here are the ones I removed sometime after buying the car

They have significant indentations where they have stopped spinning and the cams have worn away material due to the clearances closing up

But they don't have the discolouration that has recently occurred

[ukkid35]

DeadCatWalking said:

Ummm nope. You can tell the cams aren't even remotely aggressive because the contact marks don't get anywhere near the edge of the lifters. There's a 2mm band all round the edge which the lobe doesn't even touch. Aggressive cams could pump a bunch more lift out of the same duration on followers that size. I could design in another 20 or 30 bhp out of that engine by making cams that used the lifters fully without breaking much of a sweat.

There's a guy who has added a supercharger and gained just over 100 bhp, with the standard cams

My understanding is that the overlap for NA is not at all appropriate for forced induction, and because it's SOHC ideally he would need new cams - how practical is that?

[ukkid35]

DeadCatWalking said:

You may not have the evidence that your understanding of something is correct.

Steve Jones - Channel4 said:

DC this is 2019, no one cares about facts!

Ostensibly discussing Verstappen's Pole Position after Qualifying at the Mexican GP

[ukkid35]

DeadCatWalking said:

So the word "understand" is a two edged sword. It can sometimes mean " I comprehend, or have learned", and it can equally mean "I think, I believe without evidence, I heard from a random bloke down the pub, I read in the Beano Children's Guide of Engine Tuning that....."

Mea culpa

I do try to avoid claiming something as fact, especially online, unless I can prove it

I will certainly avoid using the phrase "my understanding is" in future

It may even prompt me to do a bit more research before saying anything at all