Top end tappety type noise

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I have what appears to be a tappety noise that comes in only when getting to 3100 rpm and only when under acceleration. If I lift off at any revs over 3K it stops and on the gas again and its back
I believe its a lazy follower.
FYI I have eliiminated pinking.
4.6 top hatted pocketed ported stage 3 cross bolted stealth cam kent hydraulic tappets cam about 50k miles. Engine oil/filteralways changed about every 3k

So questions are
1. how can I determine if its a lazy follower ?
2. How do I find out which one ?
3. What do I do about it (thinking new cam kit and all the ancillaries) ?
Whats your thoughts wise people ?

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Thanks guys have had Al over as well aka classichimi for test drive listen.

We thought pinking so I advanced the timing to make it pink and now I know what that sounds like on this engine its not that and havent had pinking in the past.

If I have a lazy lifter is thère a way to identify it ir us it just by measurement of the ckearnces and cam lift ?

wrt exhaust bolts we couldnt find any evidence but its really difficult on my manifolds they are custom non standard stainless and really difficult to check.

Appreciate your thoughtd folks

I am tending towards new camshaft followers and timing gear but dti old cam before removal and measure clearances to see what that shows up.

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A bit of Wynns eh......good call worth a try

£7 on Wynns or £500+ labour on new cam

Yep I will get a bottle of that first me thinks

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Already running on 20/50 high zinc oil by heritage classic oils bicester

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Useful link Ian thanks for that.

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Thanks for all the posts they are indeed helpful.

My approach this far will be
1. Check for leaks using the feather technique
2 Drop in a bottle of "lifter treatment" and see what its like after 200 miles
3. Whip the inlet manifold off and measure cam/lifter tolerances

Hope the answer lies in there

I'll be back.......

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I will try that too sounds interesting

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Update

Bottle of Wynns Hydraulic Lifter Treatment added and 10 miles driven. I think its quieter but too early to tell needs more miles

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Good debate on the thread thanks everyone.
Valve overlap will clearly be a factor on how much air can be forced out of a leak on the exhaust manifolds but as experience shows it "can" work.
Listening with a tube is good but as we all know on ours you cant get to listen to the undetside of the manifolds. However I will try both methods.
Only issue I have is the noise only appears under load under acceleration at 3100+rpm

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Just quick update.

Have been unable to find any exhaust leak and using a stethoscope I detected more noise around the rocker area.

So I have stripped the top down and removed the rocker shafts.

On removing them everything looks really good all the push rods are in great nick and the hydraulic tappets all have minimal markings and are consistent with normal wear patterns. Cam visually looks good so next job is to check the cam for correct lift on each lobe.

What I have found is that 3 of the rocker pads are not fully attached to the rockers, one fell out it was that loose the other 2 easily came out just by levering with a finger nail.

Now looking to get hold of some replacements. New thread started for that.

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Great stuff folks.

Just fyi I do have a high lift cam (Stealth) double springs too so maybe that's contributed to 3 pads detaching but none broke or fell off just they are loose in the rockers which are indeed alloy.

Whole of the top is lovely and clean, but I'd expect that as it has always had oil/filter changes every 3-4000 miles of course

The noise I was having was only at 3100 rpm and above and only under load.

In my mind I am thinking that a pad(s) are being dislodged at 3100 by centrifugal force to the extent they bounce between the rocket and valve stem emitting the noise. Below that rpm they stay put and don't clatter. That's my theory/hope yet to be proven of course

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Another update.....

Have now fitted 4 similar replacement alloy rockers thanks to big Al aka classichimi

I also inspected the cam, the lifters, the push rods and all seems well.

Its nearly all back together so wish me luck tomorrow when I will see if the rattle at 3100rpm has now gone.

If it has gone then I will get all the rockers refurbed as preventative maintenance.

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Well good news I 99% believe the tappety noise has been cured.

Reason its only 99% is I now have another issue which is puzzling.

Car ran perfectlt fine before I did this job replacing 4 rockers.

Now it refuses to idle properly keeps stalling on the driveway cuts out approaching junctions, am a bit stumped to what has happened.

Wont idle steady at all keeps cycling from almost 0rpm to 900rpm back to zero back up to 900rpm does this a few times then stalls.

Tried setting base idle but it wont idle to let me set it. Had screw fully shut then 2.5 turns open and 1/2 increments to 6 turns open no effect on idle.

What next ?

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Thanks folks. Will get chance to have ago next week. Agree that its likely stepper or leak or both.

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Now runs correctly. Combination of dirty stepper and vac leak on loose hose to brake servo unit.

Been for a drive and engine top end is certainly a lot quieter with the "loose pad" rockers replaced.

Bad news though is that engine rattle is still there at 3000 rpm.

Next steps
1.have another go at doing the exhaust gaskets although can find no evidence of a leak.

2. Look into changing big end shells.

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phazed said:

blaze_away said:

Look into changing big end shells.

Doable but fiddly!

Big ends are normally a, "knock".

More likely to be a little end imho. High mileage isn't it?

Yep have researched a bit and could be that too, difficult to decide if its rattle or knock could be described both ways. Difficult to record it as its only at 3000 + rpm under load. Fyi Alun has had a listen to it.

Car is high mileage ~240,000 engine less so about 70000

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Classic Chim said:

If it drives get it over to Dom as he’s local to have a listen Frank.
He’s got so much work I can’t imagine he’d be upset to help you with a bit of advice.
He must have heard every noise going by now.

You could always drop the pistons out through the bottom and check little ends etc if you do drop the crank.

Yeah good shout will do.

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Curious thng.........

Just bought a new timing light as my current one broke some while back.

Just marked up the main crank wheel timing marks and checked ignition timing.
According to whats showing it is so far retarded its beyond belief. Im guessing its about 25 degrees retarded.
Ie if you look at the pointer the timing marks should be about 8 degrees advanced at idle vacuum removed.
Actually the marks appear by strobè light at about 2 oclock if the pointer is a 12 oclock.

Very odd Im guessing last person in there has set valve timing all wrong and thus ignition timing is all to cock too. Not sure what to do about that.
Maybe strip and redo timing from scratch with new cam chain

Edited by blaze_away on Monday 3rd June 19:30

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phazed said:

How very strange.

The noise couldn’t be preignition could it? If your timing is all to cock as you say!

Certainly worth considering.

Unfortunately I dont have a way to hold the crank pulley so I can undo the main bolt so xant easily correct the timing. BUT I guess it must be 1/8 of 360 degrees out....Is my logic right ? ....or is it 1/8 of 180 degrees ?

If yes then if I do the timing on next cylinder in firing order it should bring me back the timing marks or is that complete bunkum thinking ?

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FoxTVR430 said:

blaze_away said:

Curious thng.........

Just bought a new timing light as my current one broke some while back.

Edited by blaze_away on Monday 3rd June 19:30

Silly question but is this the cause may be ??

Good point. I thought the same yesterday so compared new one (Mac TL650E) to old one that intermittently misses a few beats, hence new one.

Both show same as being massively retarded.