My 4.6 V8 Rebuild Thread

[400HPONGAS]

Garrycol,are you saying the piston to final bore clearance is within tolerance ,so you dont have to bore to next size,so you just baically re-ring the original pistons ?So because your using he original pistons/rods ,then maybe a static balance isnt required ? Sounds dodgy to me !!As clubgreenie has said , it will depend on whether your using offset pistons or not to correct the centerlines .

[101 Ron]

I though this was a budget build up.
What Garry is looking for is a bit more torque than a 3.5 and a basicly stock 4.6 motor, with a camshaft for his needs and timing chain improvements to overcome the rover 8 timing chain wear factor.
If the bores hone up OK and the 4.6 crank is OK for what garry is doing the motor will do the job.........he is not wanting to pull big horse power.
The 101 suffers from restrictive exhaust manifolds which cannot be easily over come.
At this stage, getting the crack TIG welded and the top of the block surfaced after the welding is the go.
I always tend to favor new pistons and rings, but if the old pistons and bore are with in spec I can see no reason why they cannot be reused and just re ringed.
The person doing the welding and block machining should quickly be able to tell him what the rest of the parts and block is like.

(Yes using the 4.6 crank in a 4.0 will need different pistons etc.......what are the pistons like in the 4.6 motor , will top hat seleeves verses machining the the 4.0 block to suit 4.6 crank etc.....Garry needs a engine reconditioner to plan the best and cost effective plan of action )

[101 Ron]

Garrys motor needs to have a increase of torque over the 3.5 and has no need to rev harder than 4000rpm.
Garry needs to know what is the best cam for his needs verses cost ?
The engine RPMs on his 101 when cruising is somewhere between 2500 rpm and 3000 rpm..........this where he wants his punch with the motor to over come the 101s high aero drag.
What is going to be the best fuelling of the motor......carbies, IFE(standard or after market) keeping in mind the cost and the wiring on the 101 is miltiary sheilded type and can be difficult to play with.
Garrys 101 is running 24 volts, but he does have limited 12volts on board with another altenater

[400HPONGAS]

If Garrys engine is to be another one of these "Budget" buildups,then why on earth use a 4.6 thats allready pre-cracked .If you cant build it properly then why do it at all ! And you wonder where this "Landrovers are UN-reliable" reputaion comes from !!!

[PLR]

G`day Gary ,

seems to me your main problem is the crack in the rear of the 4.0ltr block .

You say it is a low km block and has crosshatching .

If the case and it was done right at the time , all you intend to do ( less crack ) has mostly already not long been done .

If mine and the 4.6ltr crank is within spec , should be able to use it along with the rods from the 4.6 , if in spec and use the 4.0 pistons as i`ve read they can be used though the comp ratio is raised and they should already be mated to the holes their in . New rings and light honing if required , new bearings to suit whatever work the bigends and mains require , they may measure at std and need little .

I don`t see the internal mechanicals as being a problem as long as the 4.6 crank and rods are good .


The helicoil will unwind to look like a spring , just find the end , tap it to the middle , grasp it and with the aid of a small lever unwind it in the same direction as undoing a headbolt or leave it in there for whoever you find to do the repair so`s they can problem solve what occured and why .

I would think it could be Xrayed once apart but could cost but may surprise , the telephone would be helpful and the repair doesn`t have to be automotive just someone that knows alloy and can weld . When the crack is repaired so will the thread be and helicoils are fine if fitted right , all the other headbolt threads should be closely checked .

Efi engine will probably give better hp , torque and mile per gallon than carbs engine and although efi can be diagnosed with few special tools , carbs need even less . If you intend populated use efi would possibly be best and if remote carbs may be .

Probably six of one and half a dozen of the other in reality .

If mine i`d stay with carbs and have both lpg and petrol .

Peter .

[101RRS]

Hey guys - been away for a while - and some of you jumping way in advance of information I am after at this stage. Some need to read earlier posts.

I am starting with - a complete 3.9 with a slipped liner, a 4.6 block with at least 2 slipped liners, a 4.6 crank, pistons and conrods - the 4.6 block has no main bearing caps, I also have a long 4.0 engine with top hat liners but has a stripped head bolt hole at the right rear that has small cracks from the hole to the water passage and to the outside of the block - this can be welded up.

At this stage the 4.0 has not been pulled down but the cylinder bores show cross hatching and no major wear but will not likely need a light hone to clean them up.

My intention will be to put the 4.6 crank, pistons and conrods into the 4.0 block subject to parts passing scrutiny. And either refurbishing or using new parts for the other major components to slowly build up an engine to run on lpg and 91 RON.

I do not need a race engine just one that will need the makers general specs.

The first issue is the block - weld, hone and if the crankshaft tunnel has any issues then have it line bored but if in specs then no - just machine the crank to take appropriate size mains and big ends and assembly after balancing.

So at this stage I am just after issues to be considered with respect to the block.

Next issue will most likely be the crank, rods and pistons etc and then as on and on as I consider each phase of the build.

Lets not get too carried away here - most of the work will be done by "experts" but I will need to project manage and know what to discuss with the machinist etc.

Cheers

Garry

[101RRS]

G`day Gary ,

seems to me your main problem is the crack in the rear of the 4.0ltr block .

You say it is a low km block and has crosshatching .

If the case and it was done right at the time , all you intend to do ( less crack ) has mostly already not long been done .

If mine and the 4.6ltr crank is within spec , should be able to use it along with the rods from the 4.6 , if in spec and use the 4.0 pistons as i`ve read they can be used though the comp ratio is raised and they should already be mated to the holes their in . New rings and light honing if required , new bearings to suit whatever work the bigends and mains require , they may measure at std and need little .

I don`t see the internal mechanicals as being a problem as long as the 4.6 crank and rods are good .


The helicoil will unwind to look like a spring , just find the end , tap it to the middle , grasp it and with the aid of a small lever unwind it in the same direction as undoing a headbolt or leave it in there for whoever you find to do the repair so`s they can problem solve what occured and why .

I would think it could be Xrayed once apart but could cost but may surprise , the telephone would be helpful and the repair doesn`t have to be automotive just someone that knows alloy and can weld . When the crack is repaired so will the thread be and helicoils are fine if fitted right , all the other headbolt threads should be closely checked .

Efi engine will probably give better hp , torque and mile per gallon than carbs engine and although efi can be diagnosed with few special tools , carbs need even less . If you intend populated use efi would possibly be best and if remote carbs may be .

Probably six of one and half a dozen of the other in reality .

If mine i`d stay with carbs and have both lpg and petrol .

Peter .

Peter, Ron

You have both picked up the gist of what I am trying to. I have successfully rebuilt engines in the past and tracked them through 200,000km without major issue (Honda, Land rover 2.25 and Subaru 1800). These were built in my garage with specialist work contracted out and taking their advice. I learnt enough to know that I can do basic assembly but nothing complex but enough to project manage.

Things I have identified that I will have to consider in the future but not just now are fuel injected vs carbies; dissy vs coil packs, 3.5 101 timing cover case vs 3.9 dissy timing case vs 4.0 timing case - this choice will dictate whether the 4.6 crank will need shortening at the front, serpentine vs V belts, changing the 24v alt to a more modern version - camshaft? etc etc etc - and of course LPG induction method.

So there will be a lot to think about - the simplest would be to just slap the lot together and see what would happen and I am sure 400HP fears would come to fruition but by the same token if I go the the other extreme then the project is just not worth doing - somewhere in the middle ground is needed and I just need to pick the spots that need the extra effort and those that do not.

Cheers

Garry

[PhilipA]

Garry, you certainly have a big stack of rubbish there to choose the pearls from.

My concern about what you hope to do , is what is going on in the bore behind where the crack is in the block.
The top hat system requires sealant to be placed behind the sleeves so that if there is a crack in the block behind it, the water does not still flow south and come out near the bearings.
From various things that I have read this has become a problem in UK and why Turner make such a point , that theirs is the best.
At the very least I feel you should have the sleeve adjacent to the crack removed.
I know you want to have an inexpensive job, but I reckon if my 3.9 slips a sleeve I will buy a new 4.6 short motor, and make sure it stays cool, as I think most of the 4.6 problems are caused by the thermostat arrangement on D2 and 38A which lets the motor get too hot, aside from the batch where you could lift the sleeves out by hand as shown by the US Utube entry.
Regards Philip A

[101RRS]

Hi Philip - I share your concerns somewhat and if there was a crack anywhere else I would be looking further. The crack is not into anywhere that supports the sleeve however what I need to do once the the block is stripped is get it cleaned up and check exactly how far they go down. Looks like only a few mm but as you would know checking cracks by eye is not all that accurate. Again a Rover expert to advise. On visual inspection it looks that there is plenty of metal under the bolt hole to extend the hole but I need to get a look from the inside.

If the block is not salvagable I will get the other block top hatted (can top hats be taken out of one engine and put in another - suspect not) and use the bearing caps out of the 4.0 in the 4.6.

Garry

[mike 90 RR]

you could lift the sleeves out by hand as shown by the US Utube entry.
Regards Philip A

I remember seeing a AULRO thread with a video of removing the sleeves, via warming the block up on a gas BBQ, then removing them with hand in glove.

Cheers
Mike