My 4.6 V8 build

Hi guys, thought I'd put some pictures of my V8 build here.

All started with a top end tap on the 4.0ltr Thor in my Discovery 2. Turned out one of the thrust pads on the rockers had gone walkies and the corresponding valve stem had been trashed. With the heads coming off and the engine already being on 129K miles, I thought balls to it and decided on a full rebuild on the following spec:

• Turner Engineering top hat block
• P38 4.6 crank and rods
• 4.0 pistons kept to raise compression (roughly 10.6:1)
• Kent H180 "high torque" camshaft
• Refurbished heads with bullet valve guides
• ECU remapped by Mark Adams at Tornado Systems

First job was to strip the old engine down





And then a trip to Surrey to swap the block for a fresh one fitted with top hat liners





Along with a box of rebuild goodies



More to come....

Keep them comming

Started off by getting the block on my stand and removing all the casting flash. Basically the raged edges left from the casting process.

Before:





After:





Highly unlikely to have caused any issues (hence why it's not removed at the factory) but I couldn't put up with knowing it's there. :lol:

Next up was a lick of paint. Starting with masking off all mating faces.







Then a few coats of high temp paint.



And masking removed







Very happy with how it came out so onto the next job which was to prep the heads for refurb.

Stripped down.



And cleaned



Marks on the underside suggest it was still on it's original head gaskets.



Backed up by the head dimensions showing they've never been skimmed :nod:







So all done and ready



Heads then went to Scholar Racing Engines in Mendalsham, Suffolk for a refurb, skim, new bulleted valve guides from V8 tuner, re-cut seats and 16 new valves lapped in.

Two finished heads, wrapped up safe



Unwrapped.





Standard valve guides (Took picture before I dropped them off)



New "bulleted" guides for better flow.



Very happy with the service from Scholar. Next I cleaned up the valve gear ready for the rebuild.



Valve springs free length checked. All good.



Stem seals fitted.



Springs in.



Masked up and a few coats of silver.



Block reuild next ........

Brilliant!
I have a similar set up in mine (top hat block, 4.6 crank & rods with 4.0ltr pistons & Kent 180 cam). Runs like a dream now on LPG. I also cleaned up the flashing on the engine casting, as you say, shouldn't be a problem but nice to know all is tidy in there.
Keep em coming

Another update for you guys. sorry for the wait, depends when I get time to put the pics in order. Anyway, big one this time

Before I could start building, I needed to get on with de-ringing and cleaning up the old pistons so they could be reused with the 4.6 rods.





Then my 4.6 crank arrived.



Also with it was a set of 4.6 rods and pistons. The rods I needed, but the pistons I didn't. Due to the longer stroke of the 4.6, the pistons have a much larger dish on top to keep the compression ratio the same at 9.35:1. Here's a couple of pictures.





I could have used them no problem but a common route is to keep the 4.0 pistons, this lifts it up to about 10.5:1 compression. The gudgeon pins are pressed into the rod, and I wasn't paying for the Land Rover tool, so I needed to make something to get them out again.



The larger one supports the piston on these two flat parts, the same place the genuine tool does.



I don't have my own press so off I went to the engineering bay at work, armed with my box of pistons and a packet of chocolate Hobnobs for the guys that work there





All apart



Here's the difference in the rods. Visually identified by the number of dimples on the side, the 4.6 are slightly shorter to match the longer stroke crankshaft.





So after leaving the gudgeon pins in the freezer over night to make installation easier, I went back into work this morning to carry on.

Before starting I took the opportunity to check my torque wrench was calibrated for the build later. All good



Then I spent some time weighing and matching the pistons and rods. All 8 sets are within 3 grams of each other now.



With all that done I could come home and crack on with the build. First job was to take the main caps out of the block.



New shells in



Crank in.



Out with the Plastiguage to check the main bearing clearances.



Acceptable clearance is between 0.0004" and 0.002". Plastiguage showed a little over 1 thou so all good.



Crank back out to add some assembly lube.



Back in and Hylomar blue added to the rear main cap as per the Land Rover rebuild procedure.



Cap on along with the rear crank seal.



All torqued up.



Including cross bolts, remembering to fit the sealing washers



And here's one bit people forget. Checking for, and removing any sealant that has squashed out from the rear cap. You don't want it falling off, finding it's way into the oil system and blocking something.



Next job was fitting the pistons. First the new rings needed checking for gap which were all within limits.



I also checked the ring clearance in the piston grove, and the skirt to cylinder clearance, but didn't get any pictures. With them all fine the pistons could go in.



All done.





Big end bearing clearance checked. A touch bigger than the mains but no issues, still well within tolerance.



And all torqued up with new stretch bolts.



Finished up the block with fitting a set of ARP head studs



Thanks for reading.

Looking good keep them comming

A picture speaks a thousand words. A Really detailed thread.
I will also be using that colour scheme when I do my 4.6 in a few weeks time.
As btd said keep them coming.

Cheers guys. On with the rebuild.

First job was to get the heads fitted with new elring composite gaskets.



Torquing them up was nerve racking as there is a lot of stories on the net about the threads pulling out of the aluminium block when using studs. Some people say the 80lb-ft torque specified by ARP is too high for the block and to only do it to 65/70lbs-ft.

I decided to put my engineering head on, along with a few brave pills, and trust the manufacturer. Went with the full ARP torque loading but first ensuring the threads were spottless and giving a good settling time between each tightening sequence. All torqued up fine with no stripped threads, so IMO anyone pulling them out is either doing something wrong or has a damaged block to start with.

Anyway, with the heads on it was onto valve train. First with the new Kent H180 "high torque" camshaft.





Fitted along with plenty of cam lube.



Retaining plate fitted.



Timing gears with new chain



New cam followeres with more cam lube.



New pushrods in



As I said, one of the reasons leading to a rebuild was the damage found on the rockers.



To sort this I bought a used but in good condition rocker shaft. I then stripped my two old ones, inspected them and chose the best parts to rebuild one good shaft.



New pair together



Fitted



Next the lifter preload needed to be set up, this is the distance between the spring loaded center of the tappet and the circlip that retains it. Needs to be 40-60 thou, measured when the cam lobe is at it's lowest point (valve closed).

It's a pain in the arse to measure so common practice is to make a "go no-go" guage. My weapon of choise was the hook from an old coat hanger.



Straitened and then bent at right angles both ends.



Each end filed to the corresponding tollerance





This can then be poked under the circlip to check clearance. When the small end fits but the big end doesn't the preload is within spec. Easy peasy :thumb:



Adjustment is made by placing shims under the rockershaft pedestal.



With that setup and torqued it was time to sort the front cover.





Cleaned inside including inside the oil pump housing and removal of the oil pressure valve.





New oil pump gears fitted. Packed with vaseline to help with quick priming on first start.



Cleaned and painted outside with new crank seal, Oil filter fitted loosly to keep crap out.



Fitted.



New water pump



Moving on, vally gasket fitted.



Lower manifold fitted, cleaned but not painted to save time as it's not seen once the upper manifold is fitted.



Engine turned over to fit oil pickup and sump. Also not painted, occasionally have to remind myself this is a Landrover that goes off road a lot





And with some freshly cleaned and painted rocker covers, there you have it. One high compression 4.6 rover V8 built and ready to fit





Thanks for following guys.

Fantastic!
I wish i had the guts to have completed mine myself, i handed mine over to my Mech after doing the bottom end to fit the heads, front cover & fit back into the Rangie.
Look forward to hearing what you think to the new set up. Very happy with mine!

Yeah been good following this

Cheers guys, forgot to follow this up TBH.

So anyway. It was finally time to put it back in the hole.





New rad and thermostat Fitted.



On Mark Adams' recommendation, I got a new Bosch AFM for a 4.6 P38 range rover to match the new mapping.



It's slightly larger than the standard Discovery one. (New top, old bottom)



Got all of the ancillaries and plumbing done.



With help from the house move from Suffolk to Surrey, the running in miles went by nice and quick.



Which meant an oil change and some fresh plugs ready for running on gas.





And here's how she sits now. Well happy

Excellent

Cheers. Almost forgot that no engine thread would be complete without an exhaust vid.

very good ,but io think id have had crank polished

Many thanks for this excellent rebuild picture story; and the exhaust sounds fantastic!
BTW - any idea on what sort of hp & torque she is developing now?

Nice simplified explanation of rocker pedestal shimming. Nice build!