ratwing
Active Member
My 3.5 was very worn - on stripping down I found a big chunk of ally broken off one of the lifter bores, lots of missing cam lobes, pushrods that'd broken through the hardened cups in the rockers, a jammed oil pressure relief valve, shells well down into the copper, scored journals etc.
So I bought a so-called good 4.6 which turned out to have slipped liners, damaged pistons and bores, a worn crank, cracked oil pump gears and badly recessed seats - it was actually worse than my 3.5 and then the seller conveniently disappeared...
Well I thought, in for a penny, in for a pound and I've ended up with a decent engine by using the junk 4.6 in part exchange for a recon top hat 4.6 block and added a 3.9 cam, twin HIF6 carbs, lighter distributor springs, slightly oversize valves in the standard re-cut seats and a light porting job on the heads. I ground away any sticking out bits to match the manifolds to the heads and carbs because it only cost me my time and I think every little bit helps.
I also put in an all-steel roller chain, Yella Terra roller rockers (cheaper than new originals!), bigger oil pump gears (but kept to the standard spring strength) and a Mocal oil pump base which meant plumbing in an external oil filter.
While it was all in bits I replaced the old 4 speed box with a reconditioned LT77 too.
Following Des Hammill's SU book I had a go at re-profiling the needles (which is when I found my left and right carb pistons were different) and was reasonably successful but just couldn't get it running quite right all through the rev range. It's another £25 every time I buy another pair of needles to polish down so I admitted defeat and decided to hand it over to a pro.
Which brings me - eventually - to today and my appointment on the dyno at Atspeed in Rayleigh (Essex).
They welded a threaded bung for a lambda sensor into the exhaust, went right through the carbs and re-shaped the needles till it was running properly.
I could tell the difference driving back home, definately a lot smoother and feels quicker too.
I think the Range Rover version with efi and better ignition is around 225hp and 300ft/lb, my final run was 201bhp at 4800rpm (up about 30hp from the start) and 291lb/ft at 2575rpm so I'm quite pleased with the results and they reckon the fuel consumption will also improve so all in all a morning well spent
So I bought a so-called good 4.6 which turned out to have slipped liners, damaged pistons and bores, a worn crank, cracked oil pump gears and badly recessed seats - it was actually worse than my 3.5 and then the seller conveniently disappeared...
Well I thought, in for a penny, in for a pound and I've ended up with a decent engine by using the junk 4.6 in part exchange for a recon top hat 4.6 block and added a 3.9 cam, twin HIF6 carbs, lighter distributor springs, slightly oversize valves in the standard re-cut seats and a light porting job on the heads. I ground away any sticking out bits to match the manifolds to the heads and carbs because it only cost me my time and I think every little bit helps.
I also put in an all-steel roller chain, Yella Terra roller rockers (cheaper than new originals!), bigger oil pump gears (but kept to the standard spring strength) and a Mocal oil pump base which meant plumbing in an external oil filter.
While it was all in bits I replaced the old 4 speed box with a reconditioned LT77 too.
Following Des Hammill's SU book I had a go at re-profiling the needles (which is when I found my left and right carb pistons were different) and was reasonably successful but just couldn't get it running quite right all through the rev range. It's another £25 every time I buy another pair of needles to polish down so I admitted defeat and decided to hand it over to a pro.
Which brings me - eventually - to today and my appointment on the dyno at Atspeed in Rayleigh (Essex).
They welded a threaded bung for a lambda sensor into the exhaust, went right through the carbs and re-shaped the needles till it was running properly.
I could tell the difference driving back home, definately a lot smoother and feels quicker too.
I think the Range Rover version with efi and better ignition is around 225hp and 300ft/lb, my final run was 201bhp at 4800rpm (up about 30hp from the start) and 291lb/ft at 2575rpm so I'm quite pleased with the results and they reckon the fuel consumption will also improve so all in all a morning well spent