valve clearance tolerances

[tvrbeng]

hi,
does any one know the valve clearance tolerances for the ajp 4.2?
Engine has developed a top end rattle,i have checked the clearances: ex 0.35, in 0.15, ex 0.35, in 0.25, in 0.20, ex 0.35, in 0.10, ex 0.20.
in "mm" on the bank im sure it was coming from.
I know they should be ex 0.25, in 0.20 mm but without the old + /- tolerance im not sure if i can put the rattle down to the clearances or i should be looking else where ie little ends.if a valve spring has broken would i notice a odd large clearance??
Any info would be greatly appreciated before i enter the cam timing lion's den!
yours nervously
tvrbeng

[Tanguero]

I don't know where you got your clearance figures from but according to the manual the inlet clearance should be 0.008" (0.203mm) and exhaust should be 0.010" (0.254mm) though many set the gaps 2 thou larger at inlet 0.010" (0.254mm) and exhaust 0.012" (0.304mm)

Personally I aim to get them within 1 thou (0.0254mm) of target.

Your inlet valves are way too tight at 0.10 & 0.15mm !!! I would set the whole lot as close to spec + 2 thou as possible and see if you still have the rattle.

[itiejim]

I had a similar noise which I eventually diagnosed as collapsing gudgeon pins... My noise sounded tappetty but changed under load. Also it would become much quieter he you pulled the plug lead off the offending cylinder. Hopefully you won't have the same problem but I know that mine wasn't the first!

[Pursyluv]

Gray 101 has the answers you require having recently done his own

[Gray_101]

Inlet should be .254mm or .010 tho

Exhaust Outlet should be .305mm or .012 tho

Please note, these clearance s are slightly bigger than TVR spec, but are regarded as being a better set up than the factory recomend

Edited by Gray_101 on Saturday 6th November 23:39

[Pursyluv]

Gray_101 said:

Inlet should be .254mm or .010 tho

Exhaust Outlet should be .305mm or .012 tho

Please note, these clearance s are slightly bigger than TVR spec, but are regarded as being a better set up than the factory recomend

Edited by Gray_101 on Saturday 6th November 23:39

[Gray_101]

Tanguero said:

I don't know where you got your clearance figures from but according to the manual the inlet clearance should be 0.008" (0.203mm) and exhaust should be 0.010" (0.254mm) though many set the gaps 2 thou larger at inlet 0.010" (0.254mm) and exhaust 0.012" (0.304mm)

Personally I aim to get them within 1 thou (0.0254mm) of target.

Your inlet valves are way too tight at 0.10 & 0.15mm !!! I would set the whole lot as close to spec + 2 thou as possible and see if you still have the rattle.

Tanguero is spot on here

But if you have an early Cerb with the so called rattle cams, the tappet noise will never go away

[tvrbeng]

thanks everyone,
i shall tackle the noisy bank today, just knocking up a cam sprocket retaining tool and pick up a decent scribe.
mines a 1998 is that regarded as an early model?
they,re all noisy on start up i believe, but this was a defo change in sound which i didnt notice the day before.I dare not drive it so couldn't say if it changed with load, i jus did a quick recky n switched it off!

[tvrbeng]

Hi all,
the cam is out so far no nightmares.
Nothing obvious for the rattle but i have noticed i have fair bit of wear on the first cap n the bit the cam sits in {journal is that what its called},the aluminium looks like its come off the cap n has been deposited onto the seat below.you can peel bits off.

the cars aux shaft went last year doing a little over the speed limit, engine ran for a while with no oil pressure by time id pulled over n figured out what had happened.had new shells after that,
could the wear on the cap be a result of the aux shaft incident or is it more likey a blocked oil way?
Either way what should i do about the wear on cap 1 n head???

[Tanguero]

Certainly sounds like it could be the start of a bearing failure due to lack of oil pressure. I don't know what the answer is though as the cam bearings do not have separate inserts, the journal is the bearing.

Hopefully someone more knowledgeable will be along soon to advise

[tvrbeng]

hi,
does any one know what i can do about my worn no.1 cam journal,the cap it self isn't really worn just got sum deposite on the leading edge.sadly all the wear is on the head.
also which way does the oil flow through the cam? is the oil way on journal 1 a return to the sump or the flow into the cam?

[a1rak]

You can have the housings shaved and then line bored. Metal is removed from the joint area of the cap then the housings are line bored slightly(a few thou) off the center line. This allows removal of the wear on the upper and lower housings.

Unfortunatley this process is more difficult on the AJP head as the line boring has to be done "blind or unsupported as there is no openening in the rear of the cylinder head where the camshaft is loccated.

If it is badly scored then this cant be done. The only possible option is to overbore the housing and try and find a shell bearing that fits from another car or replace the head, there was some available in the PH classified or ebay section a few weeks ago.

Lots of AJP cam bearings seem to have scores in them, if there is plenty of good bearing area left then you may be able to clean it up and ignore it....POST UP A PICTURE

[tvrbeng]

hi,
here are the pictures of my worn no.1 journal and cap, dont think it looks very good!

Edited by tvrbeng on Friday 12th November 21:06

[itiejim]

Not nice

I'd take it to you local machine shop for suggestions - either a line bore or see if you can find some bearings to put in it as per a previous suggestion.

[a1rak]

Pictures are not good as suggested take it to a reputable machine shop. There was a set of heads from a 4.5 on ebay the guy wanted £450.00 for heads cams etc all complete and overhaulled by topcats racing in the last few thousand miles. I think it had new cams as well.
I think it will cost you more to repair properly than replace with the second hand ones if they are still available.

[a1rak]

jut looked for you on ebay they did not appear to sell on there the guy who is selling them was sonnylad search him in the members section.

[tvrbeng]

hi,
thanks for the advice
does anyone know anyone who's put shells in the cam journals or where i should start looking for the right size shells,sounds like the cheaper option.cant find a head anywhere on the net,is the 4.5 head the same as the 4.2?

[a1rak]

i dont think shells will be a cheap option as i mentioned earlier, it is a special line boring machine that is required to bore the length of the head without a rear support. Did sonnylad sell his heads then?