RV8 rebuild

[HoSS]

Hmm since my 3.5 has 125k on the clock & as i am having the manifold off anyway, i was considering doing the heads at the same time.

But how far to go?

RPI do a head kit with valves, springs, guides & seals.

I presume i will need to get the seats reground at the same time?

Skim the head?

Should i also replace the hyd lifters? How do i know if they are ok or not?

What can i easily check in the bore while i am there? (ovality, other...)

(I guess i should probably buy one of the RV8 rebuild books which are around)

Cheers

[GBMUD]

If it ain't broke, don't fix it.

The one thing I would do is, while the valley gasket is being replaced, take a good long look at the lobes on the cam. The ones for no7 and 8 cylinders seem to suffer a lack of lubrication and wear out. If the cam turns out to be sound then do not interfere any more.

Chris

[HoSS]

If it ain't broke, don't fix it.

Chris

Yeah that was plan B

Having read a bit on the RPI site, i will do as you say and have a look at the camshaft when the valley is off.

i'm getting a small amount of oil around the dizzy, but im not sure if that is pressurisation or just bad seals.

[Bull Bar Cowboy]

What it will need is really dependant upon its life history …….. has the oil been changed regularly ?……….. has it had short runs?.............what does the history look like?...................etc

Like Chris rightly say’s…………. oiling at the rear of the top end is marginal so any wear will be apparent on the cam lobes of 7 & 8. If the valley is looking very black and full of sludge then yes, the head gaskets are leaking (as opposed to blowing) into the valley and should be changed ……….. however, that is also a good sign the engine is well past its best.

If wear is apparent then to get the best from a V8 you will need work on the bottom end , probably a rebore (if the ovality is 3 thou or more), …….. definitely a replacement cam, lifters, rocker shafts, & rockers, oil pump gears, & timing gear.

At 125k the timing chain will be beyond its useful life as the OEM item stretches beyond belief ……. It also runs on a plastic cog ………… this should be replaced with quality kit such as cloyes.

To sum up ……….. a 125k of known history may be OK ………… but the RV8 is not renowned for its high mileage longevity ………. So I would only expect to see 160 -180K from a well loved motor. If it’s a 125K with no or poor history, then it will be well past its best.

With a 3.5 I would expect the parts and machining to be in the order of £600 -£800…………..

HTH

Ian

[Hybrid_From_Hell]

Another check you can do it to take out some of the pushrods (keep them in order) and check the top and bottom on them, they should be smooth and rounded, but when badly worn they get an "edge" on the smooth bit or even a tip like a biro head !.

Tappets - remove (if you can by lifting them up - if they jam do not force - its another sign of dirt or wear as they can "Flare" on the ends) and if out check the bottom for smoothness and no wear hole...

Post a pic up of the insides - picture can say a lot about the internal condition

Nige

[geoffbeaumont]

Personally, at that mileage I wouldn't spend serious money on it unless I was going to do a full rebuild.

Which is pretty much a one line version of what Ian said...

[HoSS]

Ok, so valley is off.

Camshaft didnt look to good on most lobes, so decided to do a camshaft, tappets & timing gear job.

Tappets are quite 'dished' on half of them.

Ordered a 3.9 OE cam set from RPI with duplex chain kit.

Al least then the cam will better suit the Efi which is replacing the carbs (see other thread)

Is it worth doing pushrods as well? there is a bit of a shoulder/ring around the head, but hard to tell if that is supposed to be there.

I'm not going to touch the heads for now, and will also leave the rockers until later.

[geoffbeaumont]

Ok, so valley is off.

Camshaft didnt look to good on most lobes, so decided to do a camshaft, tappets & timing gear job.

Tappets are quite 'dished' on half of them.

Ordered a 3.9 OE cam set from RPI with duplex chain kit.

Al least then the cam will better suit the Efi which is replacing the carbs (see other thread)

Is it worth doing pushrods as well? there is a bit of a shoulder/ring around the head, but hard to tell if that is supposed to be there.

I'm not going to touch the heads for now, and will also leave the rockers until later.

Pushrods are only a couple of pounds each aren't they?

I presume if you're doing the cam you'll be replacing the tappets, so I guess it'd be worth doing the pushrods so you don't risk damaging the new tappets? Given the cost of the pushrods I guess you could consider them disposable and not worry about the fact that you're matching them to worn rockers.

With a bit of luck someone who actually knows what they're talking about will be along soon to tell you whether or not I'm talking sense...

[HoSS]

Pushrods are only a couple of pounds each aren't they?

I presume if you're doing the cam you'll be replacing the tappets, so I guess it'd be worth doing the pushrods so you don't risk damaging the new tappets? Given the cost of the pushrods I guess you could consider them disposable and not worry about the fact that you're matching them to worn rockers.

yeah, in fact i just checked the cost of new rockers & shafts, its not a lot. i might just do all that too.

[Bull Bar Cowboy]

If the cam is worn………… then the rockers will be a lot worse than you think. The rockers themselves don’t wear at the pushrod or valve ends, they wear on the rocker shaft, thus reducing lift. You will most likely find very bad wear ridges and scoring on the rocker shafts……….. and yes, the rockers and shafts are comparatively cheap.

Be sure to get the shafts the right way round when you fit them …….. otherwise you will seal off the oiling hole ………… I have seen that done (not by me) …….. its not pretty.

As you have found out …….. the beauty of hydraulic lifters ………….. they have the ability to hide huge amounts of wear at the top end ………..

How bad was the cam …………… I have seen them with over 6mm worn off the lobes of 5, 6, 7, & 8…………..

Ian

[HoSS]

If the cam is worn………… then the rockers will be a lot worse than you think. The rockers themselves don’t wear at the pushrod or valve ends, they wear on the rocker shaft, thus reducing lift. You will most likely find very bad wear ridges and scoring on the rocker shafts……….. and yes, the rockers and shafts are comparatively cheap.

rockers dont look bad, the shaft has light scoring in only a couple of places, the rockers slide over it fairly smoothly if displaced sideways. I was planning to leave those for later, unless someone has a concrete reason to do them with the cam.

Its the pushrods i'm not sure about, i will take some pics later.

How bad was the cam …………… I have seen them with over 6mm worn off the lobes of 5, 6, 7, & 8…………..

Ian

I've not measured it with a dial yet, but it had the classic edges & tips wear pattern on most lobes.

that and the fact that 'while i'm in here' + the advantage of the 3.9 cam.

[Jon White]

With that mileage on it I'd be looking more seriously at what sort of condition the bottom end bearings are in - no-one seems to have mentioned them yet! Chances are all the mains and big ends will be through to the backing. (they certainly were on mine).

Whilst you're at it a replacement set of standard sized shells (assuming its not been re-ground) would be well worthwhile.

Jon

[HoSS]

Thanks Jon.

I was really trying just to do the bits that i need to while the valley is open.

I've no reason to suspect the bottom end at this time, the engine generally ran & idled ok with no nasty noises.

perhaps a bit down on power, but compression test was ok - cam may sort that.

I have a difficult situation, that i dont have my own workshop. I can book time at my companies 'car club'. so i need to do it a bit at a time.

I can do the bottom end later.

[02GF74]

rockers dont look bad, the shaft has light scoring in only a couple of places, the rockers slide over it fairly smoothly if displaced sideways. I was planning to leave those for later, unless someone has a concrete reason to do them with the cam.

Its the pushrods i'm not sure about, i will take some pics later.

if you can feel a ridge on the shaft, then that is a badg sign; no need to replace them nor rockeers unless you can see/measure wear. not that after market rockers they you woulkd get from crad/pad-docks are nasty cast iron ones so avoid if you have alloy rockers.

pushrod ends wear to a point - new ones have a flattened end on the spherical ends; if the flatted area has been worn to a point, bin them. make sure your pics show the ends.

as to what you should replace - no real answer but after all the worn stuff it is really down to budget and time.

[HoSS]

the push rods still have the flat spot on top, & seem ok close up.

Anyone know how to change the cam bearings? RAVE manuals have nothing on that. And it looks a tad tricky to access them.

[Hybrid_From_Hell]

Cam bearings.... if done properly ...are pressed in and then 'lined bored'

Not a DIY jobbie

Nige

[HoSS]

Cam bearings.... if done properly ...are pressed in and then 'lined bored'

Not a DIY jobbie

Nige

Hmm strange, as RPI were happy enough to sell me a set as "machined ready to fit" or similar.

So, do most peeps just slip the new shaft into the old ones? OOEER missus.

[Bull Bar Cowboy]

Real steel also do ‘machined and ready to fit’ ………

To do this job you really need the engine out and block stripped right down ………. I have done mine and it is NOT an easy job……….and my block was stripped right down…… even then it took me two days

The old bearings are difficult to shift and the new bearings need to be lined up perfectly. I turned up a mandrel to do the job ………..I would say leave well alone until you do a full rebuild.

Ian

[HoSS]

Real steel also do ‘machined and ready to fit’ ………

To do this job you really need the engine out and block stripped right down ………. I have done mine and it is NOT an easy job……….and my block was stripped right down…… even then it took me two days

The old bearings are difficult to shift and the new bearings need to be lined up perfectly. I turned up a mandrel to do the job ………..I would say leave well alone until you do a full rebuild.

Ian

Ok, leaving those alone then.

Got the old camshaft on V blocks with a dial, most lobes are down by 1mm or so, but one is down over 4mm! (4th from back)

Do i need to be checking the lube ways? I dont what woul cause 1 to be that bad & the adjacent ones normal wear...

[Hybrid_From_Hell]

Cos that No 7 cyl and for some reason thats the one that always wears worse

And No I don't know why but they do

Nige

[Bull Bar Cowboy]

The oilway will be clear. One of the failings of the RV8 is marginal oiling to the topend, especially the cam shaft area toward the rear of the engine. A new cam and new lifters, together with regular oil changes will go some way to alleviating this problem.

As a matter of interest, what is the the oil pressure like ? It may pay you to also replace the oil pump gears as these also wear quite badly, especially if the oil has not been regularly changed. Changing the gears is a very easy job, however, to get the best from the pump it also requires the score marks to be removed from the oil pump cover. As long as they are not too deep, the marks can be removed. It is imperative to keep the cover absolutely flat, so the method I employ is to tape some 800 grit wet n dry to a piece of ¼ (6mm) plate glass and use this a a surface table. Use paraffin as a lubricant.

Modern oils together with regular changes does seem to work. I had a good look at my cam and lifters when I recently had the heads off at 44K after the rebuild. Both the cam and lifters were showing no wear at all………. and each lifter was easily taken out from the top.

Ian

[02GF74]

however, to get the best from the pump it also requires the score marks to be removed from the oil pump cover. As long as they are not too deep, the marks can be removed. It is imperative to keep the cover absolutely flat, so the method I employ is to tape some 800 grit wet n dry to a piece of ¼ (6mm) plate glass and use this a a surface table.

the oil pump will wear at the top - in timing cover and the bottom plate. you can in theory reclaim both in this way.

[HoSS]

Yeah I was going to do the pump also.

I didnt measure the pressure before, but i have a pressure gauge which will go on after the rebuild.

RPi have some info/BS on their page about needing to replace the base, because the relief valve wears & could stick.

So i was debating wether to buy their kit or not, but its about 100 quid.

If i do recon mine. Is it worthwhile giving it a skim on a mill? or is the W&D paper way enough?

p.s. I'm going to fit a cooler as well, when i get the bits.

[02GF74]

RPi have some info/BS on their page about needing to replace the base, because the relief valve wears & could stick.

So i was debating wether to buy their kit or not, but its about 100 quid.

If i do recon mine. Is it worthwhile giving it a skim on a mill? or is the W&D paper way enough?

p.s. I'm going to fit a cooler as well, when i get the bits.

before spending £ 100, check the relief valve bore for scoring; surely it is the scroing that can casue the valve to stick but if you grind/sand them out so the bore it ends up a little bigger, I can't how the valve would stick; it may allo a bit of oil to get past but you;d have to take a lot of metal off before it is significant. Replace the spring and cup naturall

re: skim - measure endfloat first; you may not need it., see haynes manual or ask a friend to boorow one - it is standard for all pumps with that type of gear - you need feeler guage and data.

cooler , hmmmm.... don't start me on that

[Bull Bar Cowboy]

Yes, maybe BS…….. maybe not, it depends on how fastidious you are

The pressure relief plunger AND the bore scores quite badly. If you just replace the plunger and spring, then the new plunger will jam on the score marks. This is worse as the engine gets hotter due to the ali expanding. The sticking of the oil pressure relief valve is a known RV8 problem.

Over the years I have had great success with the following method………..

Carefully look at the pump body to assess the score and ridge marks. Using a VERY FINE polishing / grinding paste on a dremal mop, CAREFULLY polish the bore, trying to maintain an even finish. Deep scores need not be fully removed, all you are trying to achieve is a smooth surface i.e. removing the ridge edges of the scores. However, most of the scoring will completely polish out. By fine, I mean nothing coarser than T-Cut, as you can remove metal very quickly. Finally finish the bore with either some jewellers rouge or a similar polishing compound.

Then test with a new plunger to ensure smooth operation of the plunger in the bore. B)

You might remember the plonker that did a ‘cheque book off roader is born’ on Discovery & DVD, had the same problem the first time he took it off road…….. his cheque book must have missed the oil pump.

Ian