V8 strip down

[Fish13]

Hi Again,

I've currently got the block and crank in the machine shop and the verdict due to a bit of pitting in one of the bores is that it needs a rebore.

I will therefore need oversize pistons (this just got cheap ) and I've been looking about and seen quite a few sites that sell pistons for the 3.5V8 but are 9:75:1 as opposed to 9:35:1 at +20thou. These seem easier to find?

How much difference would these make? I am putting this in a Series III SWB and think that a rebuilt 3.5 will be plenty power enough. I don't want to put the drive train under even more strain!

Any thoughts?

[Bull Bar Cowboy]

Your block has come up really well, however, try to ensure that the block oilways are thoroughly clean………. especially the one that runs along the cam shaft to feed the cam bearings.

The main bearing caps must be in place during the re-bore as it stops the block flexing …… a good machine shop will know this already . Also, check the centre main bearing casting for cracks …….. very common …….. and if it is cracked then the block is scrap............. ask me how I know

Look for hairline cracks that lead to this …………

9.75 pistons are fine , they were for the SD1 Vitesse …………. you will be best getting the machine shop to press out the old gudgeon pins (wrist pins) and fit the conrods to the new pistons.

Also have the shop check out the cam bearings ……….. as these are easily replaced at this stage of your rebuild..

Strain on the drive train will depend upon how you drive it !

Ian

[02GF74]

Strain on the drive train will depend upon how you drive it !

Ian

an increase of 4.3 % isn't gonna put that mcuh strain.

[Bull Bar Cowboy]

an increase of 4.3 % isn't gonna put that mcuh strain.

The increase in BHP is not linear to the increase in compression ratio ………… depending on setup of the engine a 9:35 could well produce more BHP than a 9.75 (given like for like specs), however, generally speaking the 9.75 will give a few more ponies ……… but they really come into play when coupled with a ‘nice’ cam, decked block and skimmed / flowed heads, decent breathing, & decent fuelling.

Is all irrelevant really ……….. any RV8 onto a series drive train is gonna break summit if it driven like a V8 should be

Ian

[Fish13]

So the verdict is it shouldn't make much of a difference?

I'm putting a 3.9 cam in it, and I've got the camshaft bearings changed (thanks for the advice)

Or will a 3.9 cam coupled with the 9:75 pistons make it a bit much?

[Bull Bar Cowboy]

Yes, the 3.9 cam is a good choice without having to worry about the correct preloads from the lifters……… again it adds a few BHP, but its main advantage is producing a lot more low down torque.

Well done on getting the cam bearings changed ……… remember to also get the heads skimmed …….. just enough to make them perfectly flat ……. It will cost £30 ish, but well worth the effort in the long run.

Your build choice is good and you will end up with a very smooth powerful engine…………. remember you have an infinitely variable BHP/Torque control that is called the ‘throttle pedal’ ……….. just use it wisely

Now you have gone this far …….. don’t forget the other RV8 wear issues ……… have a good look at the rocker shafts …….. you will most likely find them badly worn on the under-surface (effectively the thrust area) ……… replace them and also replace all of the rockers ………… ok its not cheap, but also in the grand scheme of things its not expensive either …… replacing the shafts and not rockers is like replacing the cam and not the followers (lifters). Pushrod are generally reuseable.

What timing gear will you use ?

Tell me more …….. is the fuelling EFI (flapper or Hot Wire) or Carbs ?

Ian

[Fish13]

Hi Ian,

Thanks for the interest. I've never done anything like this before and help, advice and friendly support most welcome!

FATBOY had already tipped me off on changing the cam bearings and I can see how much sense it makes having seen the state the rest of the bearings were in! Most if not all (big ends and mains) were down to the copper.

Will definitely get the heads skimmed and use composite gaskets to keep the the same ratio. The place the block is at just now did a set of heads for a Rangie I used to own and they did a great job, so have decided to use them again for all my engine work.

I'm definitely going to replace the shafts and rockers (pretty much the whole thing will be brand new! More of a re-make than a re-build! ) I'll also get the valve seats re-cut and new valves. Hand Lapping them in will while away the winter hours!!

It's on stromberg carbs (what was on it when i got it) as I wanted to make the installation into the Series as 'easy' as possible, and I had a nightmare finding decent, working ECU/AFM for said Rangie mentioned above. I can't be bothered with all that again, and would like the relative simplicity of carbs.

Timing gear, will defintiely go for duplex, but as for make/spec, I'm at a bit of a loss and will gladly accept suggestions!

So, you think 3.9 cam coupled with 9:75:1 +20 thou pistons will be ok in a Series SWB?

Anyway, plan to do this as a winter project and then put it into Series III when it goes onto it's galvanised chassis in the spring.

Cheers for your replies so far,

Hugo.

[fisha]

Yes, the 3.9 cam is a good choice without having to worry about the correct preloads from the lifters……… again it adds a few BHP, but its main advantage is producing a lot more low down torque.

I was of the understanding that it didn't produce more low down torque . . . in fact it produced less.

I was under the impression that yes, the 3.9 cam would give you a few more ponies and a little bit more torque overall, but it did so by pushing the torque curve up the rev band a little, so you lost the low down torque.

I'm guessing that the reason for this was that the 3.9 was primarly to be coupled to an auto box and in doing so the power curves were tailored to be best around the 2000 to 3000 rpm range where most autoboxes tend to sit under average driving.

I tend to pootle around in the lower rev range and having fitted a 3.9 cam to my 3.5 block, i feel that my engine doesn't really come into power until its goes through the 2000rpm mark. So i feel as though I have to deliberately drive it on to get the best out of it. The rest of the time i sometimes feel i'm lacking in lower rev ranges cause i like to pootle along at the 1000 - 1500 rev mark. ( i trundle along at 30 in 5th )

I'd be interested to try a 3.5 cam again and see if there was a noticable difference.

[Bull Bar Cowboy]

Donald,

I guess we both maybe right in a way ……….. and I fully concur with what you are saying……… but it depends on what the definition of ‘low down’ is. I never really like to hear the V8’s labouring hard at low, low revs ……. that’s the domain of the fat fryers.

My observation was based on the following ………….. With very HC (9.75’s + decked block and skimmed heads) / 14CU EFI, and some weirdo lucas dizzy from an export model ………… I got a very healthy amount of torque with the 3.9 cam at engine speeds of just below 2000rpm (maybe 1500/1800) ……. At 2300 rpm the engine would pull like a train all day long ……….. I always found the 3.5 EFI cam to be a bit ‘flat’

However, there are two different 3.5 cams ………. The early carb version and the later EFI version ……….. Its been a long, long, time since I drove a 3.5 carb !

I think Hugo will be well pleased with what he is putting together ……… its good to see somebody doing it ‘right’………… the result will be very pleasing.

HUGO: obviously you will replace the oil pump gears and more than likely the oil pressure relief valve plunger / spring. Here you could run into trouble.

The plunger is renowned for scoring the aluminium bore, so when you fit the new plunger it could stick as the engine gets hot , leaving you with no oil pressure (common problem) .This is due to the new unworn plunger sticking on the raised score marks of the bore. If you go down this route ……… carefully, and I mean carefully ……… polish the bore of the relief valve with a dremel and cylinder mop to ensure it is smooth and that the new plunger is able to move and rotate freely…….. it will save you heartache later.

The next area is the oil pump cover ………. This sits directly on the gears and it critical to the correct operation of the pump. Often the cover is scored and it is wise to remove the scoring as much a possible. Do this by carefully, again carefully, rubbing to cover on some fine wet ‘n’ dry (600 then 800, then 1000 grit) mounted on a piece of ¼ plate glass. Use plate glass because it is perfectly flat (unless you have access to a surface table). Lubricate the wet ‘n’ dry with paraffin (because the cover plate is aluminium) and try to remove a little as possible to get an reasonable finish. That will ensure that your pump is doing the best possible job ……. and that the new gears are not picking up on the old score marks. All of the above is about 2 evening work to do properly ……. Its something that the race engine builders spend a lot of time on …….. but unlike ‘a 4x4 is born’ you don’t see them underneath wiv a big hammer tapping the pump to get the plunger to seal, after having spent a fortune on building the engine.

Timing gear wise …….. I always go for Cloyes ……….not cheap (about £50 more than OEM) but ‘fit and forget’ ……. JP is supposed to be OK as well.

Ian

[Fish13]

Ian/Fisha,

Thanks for the replies. It was Niall who first suggested a 3.9 cam in a 3.5 rebuild to me. I'll give it a shot and see how I like it! Should be fine for my Series III needs anyway!

Thanks very much Ian for the advice on the sticking spring, hadn't thought of that but did know that the sticking spring was a common problem. I'd be pretty heart broken to put so much time, effort and money into something like this and then total the engine because of something like that! Hence, all advice welcome!

Cloyes and JP seem to be the two most common uprated timing sets. I'll see what I can get my hands on closer to the time.

After I get the block back and know for sure what bearings/pistons etc etc I'll need then I'll get them and then move onto the heads. Have either of you, or anyone else that may be reading this, got any pictures of your rebuilds? Either during or finished items? I remember you Fisha posted a piccy of yours on here once at it looked fantastic. I'd be interested indeed as I'm keeping a photo diary of what I get up to myself.

Bit quiet just now as phoned today and my crank is reground but he hadn't made a start on my block yet He's very good at what he does, just not extremely quick!!!

Cheers again,

Hugo.

[Hybrid_From_Hell]

The 3.9 cam is a good fit, often also fuitted to RR as a great "towing cam" as it gives good "Grunt" low down.

Piper 270 is another good one

Make sure you fit new tappets whichever cam you use

Nige

[fisha]

Ian,

I hear what your saying about albouring at low revs. If it needs to accelerate then the gears get dropped and the throttle opened . . . . lovely

Other than that though, i do really like when your bumbling along in low revs and other folk look over wondering whats under the bonnet making that noise. i like the look of boy racers when they realise there is an engine to match the exhaust size ass opposed to a lawn mower with a 4" tail pipe.

Hugo: just for you:

[Fish13]

That's the piccies I remember! Very nice indeed! What type of paint did you use? From motorfactors or specialists?

Hybrid from Hell, yep I'll be using just about new everything and tappets are definitely on the list. Am aware that cam and tappets wear together and to change just one promotes wear on the new part. Thanks for the advice though, much appreciated.

Donald, I looooooove that sound! What type of exhaust are you running on that?

Camshaft bearings getting fitted today and he'll be making a start on the rebore so should have my now rather expensive toy back next week sometime! Then i can start rebuilding the bottom end

Thanks for the pics Donald, if anybody else has some then chuck them on. I'm going to need to decide on a colour scheme shortly!

(Oh and I'm signing up for a welding course tomorrow so the next time somebody says 'what sills, I don't see any?' when they look under my Rangie, I can hopefully do something about it!)

Cheers for now,

Hugo.

[fisha]

paint?

errr

hammerite special metals primer ( or whatever its called ) . . . basically any primer to allow to you paint on alloy.

Then . . . . . .

dulux gloss

whatever was lying about . . . i had a choice of black, lilac or grey.

lilac won.

as for the exhaust . . . really dont know. It was £35 special from Andy at Land Rover Heaven. He had it lying around and it was too good a price to refuse.

[Fish13]

Ah!!!

The lilac looks good! I'm not sure what colour to go with yet. Red and blue look very common, so might try something different! Wee while away yet so will worry about it later!

Is Andy still in business? Think I heard he is shutting up shop?

[Half Orange]

What filters are those? And is that an LPG kit I see on those Stroms? 2 mods I HAVE to do.....

;o)

[fisha]

Filters were just ebay specials. Nothing fancy atall, just came with different sized rubber rings and a jubilee clip and slotted straight on without any bother. A search for Universal air filters should turn up similar. Just be sure to check that the filters come with a set of adapter rings and its not the filter on its own.

You can see in one piccie that I have to cut away the sound proofing of the bonnet to clear the filters, but thats not a big issue atall.

As for the LPG. Yes. An OMVL millenium. It was initially setup and installed as a complete closed loop system. i.e. it has a O2 sensor welded into the exhaust and a stepper motor to control the LPG supply. Worked for a while, then the stepper started to play up. . . . dont know why. In the end I took the stepper motor out and told the system to work in an open loop mode just like how a normal carb setup would do.

[Fish13]

Hi,

After speaking with Minivin about spigot bushes, he let me know that I need to get a 1/4" cut off the end of the crank so that the Series box will mate up.

Just want to be definitely sure this is the right measurement before I ask machine shop chappy to do it? Is there any other mods I need to do that would be handy now rather than later?

Cheers,

Hugo.

[Fatboy]

Hugo,

The alternative (as per Milner instructions) is to cut 1/4" off the spigot bush adapter. I can't remember the exact details and gave the instructions away when I sold the kit but I've fitted a couple of V8's in using conversion kits and never chopped the crank.

For sure, get more detail but I would not issue the instruction to chop the crank just yet..

[Fish13]

Thanks for the tip Donald, will just leave the crank alone then I think. That way I could still use the rebuilt engine easily enough in something else in the future if I chose to.

I think when I get round to the transplant, I'm going to owe you a staggering amount of beer!

How are you getting on with the floor?

[Fatboy]

Hugo,

Black 90 got a wee tune up yesterday and passed its MOT

Rangie floor is on a list of items "to do" but will not become critical for +/- 330 days

Gonna have a clear-out because I've bought something else...... Can;t say anything at the moment but all will be revealled soon.

[Fish13]

Hugo,

Black 90 got a wee tune up yesterday and passed its MOT

Rangie floor is on a list of items "to do" but will not become critical for +/- 330 days

Gonna have a clear-out because I've bought something else...... Can;t say anything at the moment but all will be revealled soon.

Oooh I'm intrigued! If it involves V8 bits keep me posted!!

Well done on the 90!

[Diff]

Hi Again,

I've currently got the block and crank in the machine shop and the verdict due to a bit of pitting in one of the bores is that it needs a rebore.

I will therefore need oversize pistons (this just got cheap ) and I've been looking about and seen quite a few sites that sell pistons for the 3.5V8 but are 9:75:1 as opposed to 9:35:1 at +20thou. These seem easier to find?

How much difference would these make? I am putting this in a Series III SWB and think that a rebuilt 3.5 will be plenty power enough. I don't want to put the drive train under even more strain!

Any thoughts?

Just a thought with regard to the compression ratio, don't forget that the higher you go, the more likely that you will get pinking on regular unleaded fuel. Unless you are going to run on LPG, you may find that 9.75:1 is too high for regular unleaded. You may be ok if you use composite head gaskets, as opposed to the metal ones as they are slightly thicker and will result in a slightly lower compression ratio than the theoretical 9.75:1 pistons would suggest.

Most engines will run fine at around 9:1 on regular unleaded in the UK. Much higher, and you MAY need to retard ignition timing, and closer to 10:1 MAY need superplus unleaded/Optimax or LPG.

Regards,

Diff

[pugwash]

i have to say that i disagree with this completely.

my last 4.0 was a tophat linered, blueprinted block. CR was a tadge over 10:1 (i wanted 10.5:1 but couldn't get it from machining alone without a lot of buggeration). I had power in buckets, and usually returned over 22mpg with town and motorway driving combined.

i had no problems at all with this setup running on a good quality 95RON unleaded- in fact the ignition was never retarded once. My calculations suggest that you can run an engine happily at 10.5:1 on optimax. indeed modern engines quite often run over 11:1 with a knock sensor on them- think the ferrari V8 and V12 run almost 12:1 sometimes !!!!!!!!

if you have any ideas at all to run LPG then go for the highest CR you can- the greater CR will lead to lower piston temps (always a good thing), and better power and economy.

[Bull Bar Cowboy]

Yep ……… I agree with Jim …………. I built mine to come as close as 11:1 as possible…………. and provided your timing is perfect, then these engines will run fine on 95RON. This is where the fully managed engine system scores…….. timing and fuel are dynamic, thus always giving the best performance.

Give yourself an eye opener and carefully put the strobe on a V8 dizzy engine …….. depending how worn the dizzy is , the variance any given rpm is alarming (I’ve seen 5 degrees of wander, although 1 – 2 degrees is typical)……… with EDIS or full engine management this just doesn’t happen…… the strobe sits there like its nailed to the crank pulley

Mainly due to timing issues I have reduced my CR to a around 10:4 ish ……..easily achieved by moving from the thin tin’s to the thickest compo I could find (dropped by 0.7:1)……….. compared to other areas of the world (including the USA) our petrol is of good quality here.

With LPG the higher CR is fine due to LPG having a high octane rating ……. However, the calorific value is less so the fuel actually is about 10% less efficient than petrol….. also LPG burns significantly slower, therefore the timing needs to be very advanced to get the best out of it.

my last 4.0 was a tophat linered, blueprinted block. CR was a tadge over 10:1 (i wanted 10.5:1 but couldn't get it from machining alone without a lot of buggeration).

I suppose it depends on the setup (I asume yours was an SL engine ) ……….. flat tops (f’kin expensive), decked block, heavily shaved new style heads (smaller combustion area), takes you to these sort of CR levels. Much above 11 and the heads are getting very thin indeed. An alternative to flat tops is std 9.75’ s machined and then the block machined to match.

Right now I am severely pee’d off with the V8 …….. just replaced the valley gasket as the RTV let go on the rubber seals …….. dumping a litre of oil in 600miles ………. got it all up and running again in an evening and now have a ‘chuffing noise’….. this usually points to a failing exhaust manifold gasket ………. but I cant see anything obvious, and I don’t want to remove the headers just for fun

Ian