Thread: Measuring lifter preload without removing inlet manifold - Rover v8

No AFAIK you have to remove the manifold.
Then you make up a feeler gauge to 20thou. I used a coathanger which I bent 90degrees about 2-3Mm at the end then filed it down to 20thou.
You then have to check whether the gauge fits between the plunger edge of the lifter and the body of the lifter.

Regards PhilipA

http://www.v8engines.com/engine-4.htm#pre-load


Setting Tappet pre-load step by step Whilst most Rover or other publications do not touch on this subject, it is extremely important (if assembling your own top end) to carry out this operation. If you fail to do so, all may not lost and maybe you'll not have problems, but the symptoms for those not so lucky will be lost compression on one or more cylinders, and noisy tappets.

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[TD]Checking tappet pre-load can be quite difficult and, as there are no special tools as yet available for it, you will need to select varying sizes of welding rod, or fabricate your own.[/TD]
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[TD]The allowed tolerance is 20-50 thou. which is the distance measured between the top of the tappet's piston and the retaining circlip. Each one needs checking individually with the cam ideally 108 deg. off its lobe. [/TD]
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Nicely oiled with cam shaft lube (the red stuff)

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[TD]To create your own tool, all you need is a welding rod and a suitable device to measure it with. This rod is 60 thou, your best bet is to create 2 rods, one at 20-30 thou. and the other at 50-60 thou. This will tell you if your tappets are out of the allowed tolerance, more rods will be needed to judge what size shims to fit.[/TD]
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[TD]Once you have ascertained the measure of the tappets, pre-load adjustment is achieved by fitting special pre-load shims under the pedestals. But beware, the rocker ratio is 1.6 that of the clearance that needs correcting, so a 16 thou. shim will make approx 25 thou. difference.[/TD]
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[TD]You MUST find an average shim size, and fix it to EVERY rocker. So, for example, if you find that you have 4 tappets at 70 thou. and 4 at 80 thou. you would put 32 thou. shims on all the pre-load of the tappets, making the 70 thou. tappets 25 thou. and the 80 thou. 35, thus all the tappets are within, or closest possible to, the allowed tolerance.[/TD]
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[TD] To attach the shims, you need to slacken all 8 of the 14mm bolts.

Then, one bolt at a time, nearly remove them so you can slide the shim underneath, then slightly tighten the bolt so nothing slips or slides. Do this for all 8 rockers.

Then to tighten the bolts, start with one bolt and tighten by a couple of turns of the spanner, then go onto the next one. Keep going round till all the bolts are tight. The eventual torque setting for the bolts is 35 Lb/ft.
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You can make your own shims using shim bronze sheets, but they are a bugger to cut and drill. You have to make sure you leave a keyhole to uncover the oilway. It's best to drill them on a piece of wood and clamping either side of the proposed hole. Look at the bottom of the rocker pedestal for the size.
However if the heads have not been shaved it is a luxury as I doubt very much that any mechanics do it.

Regards PhilipA

Originally Posted by Roverlord off road spares

Whilst most Rover or other publications do not touch on this subject,

That is because for a largely standard engine being rebuilt with standard parts it is not necessary to measure preload.

I have rebuilt a 3.5 and built a 4.0 as a 4.6 following LR Overhaul Manuals LRL 0164 and LRL 0004 and it is not covered in there and I had no issues.

The only related points the manual raise is to ensure the right rocker pedestals go in the right place or oil flow will be blocked. The only other relevant commentary is to endure the tappets are immersed in oil before fitting and to pump them up to prime them with oil before fitting to reduce tappet noise on first start. The manual have a not that tappet noise may still be evident and to run the engine at 2500rpm for a few minutes until the noise stops.

So with a standard engine, with standard parts and correct installation it should not be needed.

With the 4.6 I built, the block had been damaged so was shaved down a bit to level it and the heads were on their second recondition so had been levelled twice and the engine went back together fine with no tappet noise and no issues.

Garry

Thank you all for your replies. I have an issue at the moment where I have lifter noise when warm at idle & when under load in 3rd or 4th up a hill. It’s more of a ‘pounding’ then a ‘ticking’, which makes me feel that a lifter or two is bottoming out, rather than topping out. The issue only began after fitting recon 3.9 heads to my 3.5 recently (bottom end of motor only 50,000km old, so shouldn’t be any noises from it). I was in a big rush & stupidly did not measure the preload. I was hoping there was a way to measure preload with the inlet manifold on rather than just trying different shims aimlessly. Probably best that I just pull it off and do it properly. These recon heads are only a tad thinner than the 3.5 heads, but for some reason the valves are much shorter (by almost 2mm). Thank you all again.

The issue only began after fitting recon 3.9 heads to my 3.5 recently

Hmm.
Are you sure that the 3.9 heads were not composite gasket heads?

Composite gasket heads are about 40thou thinner than 3.5 steel shim gasket heads.

Did you fit composite gaskets or steel shim gaskets?

If they were composite gasket heads then you need to fit composite gaskets.
Regards PhilipA
BTW the way to check is to measure the combustion chamber volume .28CC equals composite. You need a bit of Perspex, and a burette. AFAIR tin is 32CC.

If either the heads or block have been machined then it would pay to check the clearance although being hydraulic lifters its usually not required for a mild skim.