What has happened to my lifters?
Discussion
stevieturbo said:
Their quoted 1.625" as an oversize...is still smaller than the 42mm mentioned in this thread. 42mm seems a pretty big follower.
I agree , Is this the exact size ? I had a look on the net and the diameter quoted seems unusually large.Have you tried contacting Piper or Kent etc; and asking ?
It is possible that the followers are unique to that engine model , but more likely sourced
from a stock engine parts catalogue.
The size and solid configuration definitely suggests an OHC engine , 2v/cyl ,(if 4v its a big'un with followers this big !) possibly a commercial vehicle application of a few years ago as hydraulics probably are used nowadays.( can't think of any really large capacity /high perf OHC car engines of that era , but maybe someone knows better )
There are manufacturers specialising in ( mass ) producing followers for the motor industry , perhaps some enquiries to be made.
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)generally they are fairly small, as they're for small 4v per cylinder heads, so springs etc tend to be small.
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
Newman cams did some early work with TVR and certainly had several ajp8 cam profiles on file when I spoke to them about 15 years ago (when I was after some cams the factory didn't have any cams or followers!)
They also did the very first SP6 cams and followers.
Also you could speak to Gt Automotive who certainly used to advertise SP6 cams direct but then said you had to deal with Dom .. so they might do AJP8 stuff too, but you might be dealing with Dom rather than direct.
http://gtautomotiveparts.co.uk/performance-product...
Just couple of other avenues if you don't turn up anything OE.
They also did the very first SP6 cams and followers.
Also you could speak to Gt Automotive who certainly used to advertise SP6 cams direct but then said you had to deal with Dom .. so they might do AJP8 stuff too, but you might be dealing with Dom rather than direct.
http://gtautomotiveparts.co.uk/performance-product...
Just couple of other avenues if you don't turn up anything OE.
ukkid35 said:
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?
No need at all for the lifter the be that size, for what is moderate lift really.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
But a bucket lifter needs to be big enough to fit over the valve/spring.
The cam lobe does run almost to the edge of the lifter .. the base circle is large therefore the tip of the cam lobe is a long way from the cam centre line.
The marks on the lifter appear to more or less go towards the centre of the lifter itself so the action of the cam lobe wiping across the surface is causing it, but actually what it means I don't know if you can't feel anything on the lifter surface.
It also looks like the lifter has been turning, but there is a square pattern to the centre suggesting it tends to run in one position more of the time, but don't know if that's significant. I'm not an engine builder.
The marks on the lifter appear to more or less go towards the centre of the lifter itself so the action of the cam lobe wiping across the surface is causing it, but actually what it means I don't know if you can't feel anything on the lifter surface.
It also looks like the lifter has been turning, but there is a square pattern to the centre suggesting it tends to run in one position more of the time, but don't know if that's significant. I'm not an engine builder.
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 leftAll 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
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
Perfectly normal looking lifters. The striations are contact stresses in the skin of the case hardened steel. The deposits are something out of the oil but not worth fretting about. Rub them over on some 240 grit wet and dry on a flat block with some paraffin in circular motions. I actually like a tad of surface scratching on lifters. Gives the oil somewhere to sit like in the cross hatch on a honed cylinder bore, helps the lifter rotate.
The shallower markings are normal ,the pitting is a sign that the contact surface is either corroding ,( highly unlikely given the oil rich environment) ,or beginning to brinell ,ie surface starting to fatigue fail , which in well designed/specced valve gear can sometimes take a long while to become a major problem.
The more pronounced deep looking scores are IMO definitely not normal , if they can be felt with a finger nail scratched across the contact surface the followers are scrap.
Re refacing using w+d ,OK for the shallow markings but I generally use 800 grade !
The experience level of the engine assembler also need to be taken into consideration.
The more pronounced deep looking scores are IMO definitely not normal , if they can be felt with a finger nail scratched across the contact surface the followers are scrap.
Re refacing using w+d ,OK for the shallow markings but I generally use 800 grade !
The experience level of the engine assembler also need to be taken into consideration.
Auntieroll said:
The shallower markings are normal ,the pitting is a sign that the contact surface is either corroding ,( highly unlikely given the oil rich environment) ,or beginning to brinell ,ie surface starting to fatigue fail , which in well designed/specced valve gear can sometimes take a long while to become a major problem.
The more pronounced deep looking scores are IMO definitely not normal , if they can be felt with a finger nail scratched across the contact surface the followers are scrap.
Re refacing using w+d ,OK for the shallow markings but I generally use 800 grade !
All the markings are normal. The OP says nothing can be felt with a fingernail. I've examined thousands of such lifters over the years and resurfaced hundreds for race and road engines. Usually on a grinder for damage deeper than a thou or so but by hand with W&D for a quick clean up. Depth of case on steel lifters like this is about 15 thou so it's acceptable to regrind by about 8-10 thou for bad pitting or scoring.The more pronounced deep looking scores are IMO definitely not normal , if they can be felt with a finger nail scratched across the contact surface the followers are scrap.
Re refacing using w+d ,OK for the shallow markings but I generally use 800 grade !
800 grit on hardened steel will be about as much use as toothpaste or a kitchen scouring pad. 180/240 will remove a small amount of metal which is all these need.
DeadCatWalking said:
Perfectly normal looking lifters. The striations are contact stresses in the skin of the case hardened steel. The deposits are something out of the oil but not worth fretting about. Rub them over on some 240 grit wet and dry on a flat block with some paraffin in circular motions. I actually like a tad of surface scratching on lifters. Gives the oil somewhere to sit like in the cross hatch on a honed cylinder bore, helps the lifter rotate.
Sounds like the voice that's been missing from this place for a while.
ukkid35 said:
however the std cams are aggressive with 0.5" lift
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.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 camsMy 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 said:
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?
What overlap for n/a, and there are many types of forced induction ?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?
Both very open ended.
But for most superchargers...just blast away and never worry, the chances of the cams being that "big" for wont of a better description, is fairly slim.
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