Thread: 4.6 Rebuild

The 4.0 was fine and had no troubles.

Originally Posted by p38arover

I'm not convinced that the additional power is worth the cost of the new pistons (165kW vs 157kW) - new pistons will add about $1000 to the job.

I'm not sure yet what the higher compression pistons will give with a Stage 2 camshaft so I guess I'll be asking Bruce Davis for a bit more info.

If the pistons are even higher CR, e.g., 10.5:1 it might work well with LPG injection which is also planned for the car - and maybe a UniChip fitment.

Re the 165kW vs 157kW (221 bhp vs 210 bhp), is that 11 bhp difference going to be noticeable?

Looking at Piper Cams website, it appears their
V846BP270 Fast Road Cam with a power band of 1000-5500 rpm gives a 21 bhp improvement (I suppose that's with a head rework). However, Dave Hammill in his book "How to Power Tune Rover V8 Engines" indicates this cam will need Piper valve springs as there isn't enough clearance with standard springs.

More cost.

I've emailed Bruce Davis for more info on his pistons and cam and expected power gains.

I've also emailed Graeme Cooper asking if they have any dyno graphs for the 4.6 with a UniChip.

Decisions, decisions.

Ron

Originally Posted by p38arover

I've emailed Bruce Davis for more info on his pistons and cam and expected power gains.

I've also emailed Graeme Cooper asking if they have any dyno graphs for the 4.6 with a UniChip.

Would you believe that the email address for Bruce Davis as listed in the White Pages on-line is wrong? The message bounced.

Next, would you further believe that the email CGI script on the Graeme Cooper lrexpert.com site didn't work either? Fortunately I got an email back from their webmaster telling me that.

Gaaah!!

Anyway I rang Bruce this morning but got some info. The pistons are Hepolite 9.35:1. The cam has slightly lower lift than the original cam but gives more torque down low - it peters out above 3500-4000 rpm.

I forgot to ask him about power gains.

I started cleaning up the old 8.37:1 LC pistons this morning and the skirts are hardly worn. If they were clean, they'd look new. I'm having problems justifying their replacement. One piston has had a bit of blow-by. The rings were a bit sticky and carboned up in that piston.

I haven't checked to see if it is the same cylinder that has a bit of a ridge.

Currently, I know which piston came from which cylinder and I'd maintain that relationship if they were going back into the same liners.

However, if I decide to reuse them and noting that I'm having new liners fitted, does it matter if they get mixed up? I'm not keen on stamping the pistons or conrods with identifying marks - dunno if it will cause weak spots.

Ron

Originally Posted by p38arover

Would you believe that the email address for Bruce Davis as listed in the White Pages on-line is wrong? The message bounced.

Next, would you further believe that the email CGI script on the Graeme Cooper lrexpert.com site didn't work either? Fortunately I got an email back from their webmaster telling me that.

Gaaah!!

Anyway I rang Bruce this morning but got some info. The pistons are Hepolite 9.35:1. The cam has slightly lower lift than the original cam but gives more torque down low - it peters out above 3500-4000 rpm.

I forgot to ask him about power gains.

I started cleaning up the old 8.37:1 LC pistons this morning and the skirts are hardly worn. If they were clean, they'd look new. I'm having problems justifying their replacement. One piston has had a bit of blow-by. The rings were a bit sticky and carboned up in that piston.

I haven't checked to see if it is the same cylinder that has a bit of a ridge.

Currently, I know which piston came from which cylinder and I'd maintain that relationship if they were going back into the same liners.

However, if I decide to reuse them and noting that I'm having new liners fitted, does it matter if they get mixed up? I'm not keen on stamping the pistons or conrods with identifying marks - dunno if it will cause weak spots.

Ron

Mix 'em up, won't make a lick of difference

Originally Posted by rovercare

Mix 'em up, won't make a lick of difference

That's what I thought. Thanks, Matt

Ron

I think it comes down to should you bite the bullet and put new ones in whilst the engine is out and its cheaper not having the labour, if the old ones are ok i see no problem using them. The horse power would be noticeable but for what you use it or ron, do you need it, and $1000 plus for 10 odd horspower is alot. I would put a decent exhaust on it for the money instead

Originally Posted by Ace

$1000 plus for 10 odd horspower is alot. I would put a decent exhaust on it for the money instead

Dunno. pistons will add power across the rpm range, I'm not sure an exhaust system would. Also I don't want a noisy exhaust nor one that booms into the cabin. They become very tiring on a trip.

I consider my standard P38A to be too noisy inside.

A bit of bad news today. I sent the radiator (new last year) for servicing. They told me it is stuffed. It's been pressurised by the previous engine and has spread the core and broken the sides off it.

Another $600 to find.

Ron

As you know I'm having the original 4.6 block fitted with top-hat liners, high compression pistons, high torque cam, new lifters, and my oil pump modified.

That work has been completed. It struck some unexpected snags, e.g., Davis' said my crankshasft was stuffed so I needed an exchange unit (it looked OK to me but I'm no expert).

Also planned was to have the heads flowed and the ports matched. So I pulled my present engine out last week and dropped the heads over to Davis'. I got a call on Tuesday to tell me that the heads are stuffed. I'd recently had the heads skimmed and fitted with new bronze valve guides. The quote to repair the heads, flow them, and match the ports had gone to $2500. The original quote for flowing and port matching was $500. The new figure includes new guides and, I think, new valves plus machining the inlet manifold to suit.

I've sourced some second hand ERR4323 heads today but they've been skimmed already so I'm a bit reluctant to use them. If I'm spending the money I'd like to start with unskimmed heads to leave teh maximum metal on them.

The trouble is where do I stop? I've invested a lot already. My wife says don't worry about it, just do it.

Ron