My 4.6 V8 Rebuild Thread

Freestyler · 16th May 2012, 08:34 AM

Hi Garry My father has a 4.6 in his county I have a 4.4 terrier in mine with a HC 4.6 sitting in the shed to rebuild and go into mine. If the 4ltr block has a crack in it I wouldn't us it. I haven't read any other replys so I am sorry if I go over something already touched on.

A resleeve with T sleeves on a 4.6 block is around $1000. If you wish to go out back you don't want to slip a liner out there!! cost you alot more than $1000 to recover it. The slipping liners is the main flaw in the 3.9, 4, and 4.6. It is due to the cylinder walls in the block is alot thinner and therefore get alot hotter. The Oil temp gets way too hot in these engines. You will not see it on the water temp gauge until it is too late. Dad's truck got to 105 on the water temp and 135 on the oil temp towing his caravan one hot day in December last year. The oil should be cooler than the water! If you have all the bits for you 101 you will be right as they had an excellent oil cooler on them. The only issue is you have to run the correct oil filter! the Z9 will fit but is not the correct filter as the 101 has a higher capacity, higher pressure system than any other rover. Donalson make the right one which I run and noticed an increase in oil pressure straight away. Since putting an oil cooler on dad's truck no matter how hard you push the engine on a stinking hot day with the AC flat out the water temp wont go over 92 and the oil 80

If you wish to run it on LPG I would suggest going to high compression. If you don't on LPG you will get poor fuel economy, a noticable drop in perfomance, and it will run hot. I run my terrier a 10.5: 1 all you have to do to run it out west on poorer fuels just retard the timing about 3 degrees which is not hard. I have two marks on the dizzy for this reason. Or take some octane booster.

I have the early Hot Wire EFI system on my truck, easy to fit as they had a separate wiring harness to the mian one in the vehicle for it. Carfully pull it out of a Disco or Rangie and fit it. You would need to rechip the computer for the 4.6. You can also get a sandwich plate for the ram tubes making them longer and giving you more torque.

If you stick to the carbies you would have to change the needles and you will find it will run out of air very low in the reves

My Father spent $10000 rebuilding his engine and it is awsome. Heading North up the F3 it pulled 120 up Mooney Mooney in 5th and didn't even look like slowing down.
Tim

**400HPONGAS** · 16th May 2012, 09:31 PM

Freestyler,you should read the entire thread from the beginning ,then you might notice the sleeves and cracks
The "oil gets way to Hot in these engines " Pray tell ,what engines are you comparing it with to make that assumption ?What is the correct range for oil temp anyway ?
Is this with or without the standard oil cooler arrangement ?
The oil should be cooler than the water ??? What , never in any engine ever manufactured would that apply !!!!!By the way ,the 135c oiltemp for 105 Water temp is about standard !
How does the 101 have higher capacity (bigger sump and cooler perhaps?),Higher pressure system ?(screwed up relief valve ,that makes heaps of heat)
If your dads engine only gets the oil temp to 80C , then you better tell him to replace the oil every 100 K , as it will be totally imulsified, and his engine bearings will be crap.
Sandwich plate for the ram tubes ,gives you more torque , absolute rubbish, at the best it may pull the torque curve back 50 RPM , waste of time.
A 175Cd Stromy with the right needles can easily feed 225CFM ,2 will get you 400CFM ,way enough for 300HP ,why waste time and money on EFI ?
Only spent $10000 ,is that good or bad ?

**ozscott** · 21st May 2012, 02:07 PM

Ok - so what options do you have now for a 4.6. Original block or 4.0 stroked to 4.6. A second hand 4.6 RR motor and re-coed. A new cast 4.6 - I understand these only come from the UK.

As to who sells re-coed 4.6 in Australia - I guess TRS might be the main mob - although they seem to be selling short motors on their web site at least.

I know MR automotive build a nice 4.6 based on a 4.6 block crack tested and machined up (they dont do the machining but to assembly and fitment etc).

Anyone else who regularly does the 4.6 in house or as new casting?

Is the freight worth it for a new cast from UK? Apart from the problems if they fail under warranty?

Cheers

**101RRS** · 7th August 2012, 03:35 PM

I have now stripped the 4.0 down to a bare block - given the state of the bearings and camshaft the engine has virtually done no work with virtually everything in as new condition.

The issue is the crack joining the head bolt hole. On cleaning the block up I can see that the crack on the outside has been pinned and welded. What I need to get done is for the helicoil removed, 3mm deep slots dremmelled where the cracks are, then welded up with a little extra reinforcing welded on the outside to support the thinner stud walls. I am taking the bare block to a local head place tomorrow that has the correct gear etc for alloy head welding for them to have look.

If they believe they can do it i will get them to weld it up and put in a threaded insert rather than a helicoil.

Can anyone recommend a book that is specific to rebuilding Rover V8s?

Cheers

Garry

**101RRS** · 8th August 2012, 05:02 PM

I took the block to the first place on the list - a "head" shop but they said they did not have the ability to weld cast aluminium so off to number two on the list - again they are a head shop but also do engine rebuilds (just rebuilt my neighbours 4.2 Jag engine). They said they could do it but indicated that they only had a basic tig machine that would put a lot of heat into it and could cause issue with the nearby liner. They recommended a local radiator guy who has a very high tech machine that auto water cools the job and can control the power with a foot control as the weld progresses. Might the usual piece of kit anywhere else but in the car backwater that is Canberra this is rare.

I had forgot about this guy had actually used him to weld up the thermostat housing on my 101 a little while back and to weld up parts of my Air con in the Freelander - all top work. Expensive though.

He says he can do it but there is a bit of a risk of heat but the water cooling process should keep it in control. He said most of the hole will be filled and he will leave the weld proud of the block deck do be brought back down when the deck is levelled.

The hole will have to be drilled and tapped and I will be putting in head studs rather than using head bolts.

Where is the best place to get head studs?? (Turners UK??) I guess I also will need a new set of main bearing cap bolts and big end bolts.

One thing I am not so sure off are the little ends - what is the go with bearings and gudgeons? I will discuss with the engine rebuilder but want to be fore armed with information.

Cheers

Garry

**MacMan** · 8th August 2012, 05:23 PM

I bought my ARP studs from Fabre here in OZ. Some have bought ex US but I was happy to buy local.

If you're going to all the effort to make a bad block good, I'd consider it an unnecessary cheap-out not to have the crank machined and balanced and all bearings replaced. My latest experiences with second rate mechanical parts leads me to suggest you buy local. It's much easier to send things back if they are faulty or not as ordered.

**101RRS** · 8th August 2012, 06:07 PM

Thanks - a different crank, pistons and rods are going into this block so all bearings etc will be renewed - size dependent on the crank journal size after it is checked/machined.

**clubagreenie** · 8th August 2012, 06:08 PM

Agreed, Fabre are reasonable for price and freight and also usually have them in stock. There's a guy here in Sydney (North Parramatta) if you get stuck that does good work restoring Merlins incl having the alloy rebuilt from donor dead blocks.