Cylinder head

[Chimp871]

Now I've got the engine out I plan to remove the heads this weekend.

I want to start measuring tolerances etc but the ajp engine rebuild manual I have from in line doesn't mention what tolerances are for valve guides, valves, spring length etc only how to out it together. I could buy new parts to compare but I really prefer to know what tolerance specs are.

Anyone know a source for the various roller bearings on the 4.2? Can't seem to find them on the usual sites.

Cheers

[Jhonno]

Roller bearings are all available from other suppliers..

I got mine from 2 different places. For the half time bearing you will have to specify a metal cage or you will likely end up with a composite, which is marginal for temps.

[TwinKam]

Chimp871 said:

Now I've got the engine out I plan to remove the heads this weekend.

I want to start measuring tolerances etc but the ajp engine rebuild manual I have from in line doesn't mention what tolerances are for valve guides, valves, spring length etc only how to out it together. I could buy new parts to compare but I really prefer to know what tolerance specs are.

Anyone know a source for the various roller bearings on the 4.2? Can't seem to find them on the usual sites.

Cheers

I sourced most of my 4.2 bearings and seals from BRT Bearings, I believe they're national, but I deal with Simon the manager of the Fareham branch (between Portsmouth and Southampton). 01489 886880
A more knowledgeable and helpful guy you'd be hard pressed to find. By all means mention my name ('Rik') and in the same breath 'Cerbera engine bearings'; he'll doubtless groan
Not sure if they do mail order, but he may be able to arrange for you to pick up from your nearest branch.

[ukkid35]

There are three different sizes of head bolt washers

If you find a source of replacements please let us know

I ended up sanding mine down and reusing them, which is not ideal

These are some of the worst

[Chimp871]

I will Ukkid. Good call on the different washers, at first sight they all the same.

Anyone have a torque adapter for torquing down the heads for loan? Happy to pay a deposit.

[Jhonno]

One thing to look for with the valves, is stretch..

[ukkid35]

My old intake valves were 120.3mm vs 120.0mm for the new ones I fitted, they probably had about 60k on them

Shims allow for a total adjustment of about 2.0mm, so valve stretch is definitely a contributor, but I guess valve seat wear accounts for the remainder of the change

[TwinKam]

Chimp871 said:

I will Ukkid. Good call on the different washers, at first sight they all the same.

Anyone have a torque adapter for torquing down the heads for loan? Happy to pay a deposit.

YHM

[Chimp871]

Twinkam - didn't get an email mate. But if I don't get this back together by Friday next week, it'll have to wait 3 more weeks as I'm away.

Removed the pistons, main caps and crank. Getting the main caps off was fun!

I've got a 2.5" journal crank on a 96 4.2 which is weird and no receipts in the file to show any crank work done. But it's a relief! Someone Tanguero?) siad if you have 1 oil sump plug = 2.5" crank, 2 oil sump plugs = 2.25", I have 1 sump plug so perhaps it's an accurate statement?



Main and big end bearings look decent, will post pictures over the weekend. Plastigauge the main journals and they were 2 thou. Piston ring gaps, top and middle, between 19 and 28 thou. Haven't measured bore diameter or crank journals yet. More work to be done.



On parts : getting main and big end bearings, no problems.

Getting 4.2 pistons rings - nightmare. £30+ for 1 piston set Need to speak to Dom whether he can quote on a full set instead of individually.

Anyone know a source on rings that costs less than £280?

One questions I have is the thrust bearing was on #4 journal (#5 is rear) not #3. Is this correct? EDIT: #4 is correct for thrust bearing

Edited by Chimp871 on Friday 5th July 18:39

Edited by Chimp871 on Friday 5th July 18:41

Edited by Chimp871 on Saturday 6th July 16:10

[Jhonno]

TVR Parts for piston rings.

If you have a '96 with a 2.5" journal crank you have a new engine. Or someone has line bored your original one. Lucky you though!

2 sump plugs is definitely a 2.3", 1 sump plug could be either.

[Byker28i]

Chimp871 said:

Getting 4.2 pistons rings - nightmare. £30+ for 1 piston set Need to speak to Dom whether he can quote on a full set instead of individually.

Anyone know a source on rings that costs less than £280?

Seems about right, my engine was just a refresh as the bottom end was ok, the brass valve guides had worn, however I had my small bearing crank converted to a large, refreshed the whole engine as it was apart, but prices I paid were:

2x Chilled cast camshafts £500.00
2x Cylinder head gaskets £190.00
16x Cast valve guides £300.00
16x Valve stem seals £64.00
16x Tuftrided valves £280.00
16x Cam buckets £272.00
16x valve guides (2 oversize) £360.00
16x Valve springs £320.00
8x Piston ring sets £240.00
Main bearings (2 sets for small main) £160.00
Big end bearings £70.00
Aux bearings £132.00
Larger main bearing crankshaft £1750.00
Line bore block to suit larger crank £475.00
1x Timing chain £85.00
1x Chain slipper £90.00
O rings and seals £90.00
Aux shaft & modified pulley £225.00
Big end bolt kit £80.00
Front seal housing & adaptor £90.00
Consumables £40.00

etc etc, the list goes on. £7800 in bits and machining, £2200 for the labour and £2k for vat

Just so you're wallet is ready

[Thom]

I asked a short while ago about a possible correspondence between crank bearing size and sump plugs and it appeared there was none.

https://www.pistonheads.com/gassing/topic.asp?h=0&...

[Jhonno]

Thom said:

I asked a short while ago about a possible correspondence between crank bearing size and sump plugs and it appeared there was none.

https://www.pistonheads.com/gassing/topic.asp?h=0&...

Other than an original twin plug will be a small journal.

[Chimp871]

Thom said:

I asked a short while ago about a possible correspondence between crank bearing size and sump plugs and it appeared there was none.

https://www.pistonheads.com/gassing/topic.asp?h=0&...

That's the one I was trying to remember. Jhonno had it right.

Edited by Chimp871 on Monday 8th July 22:28