how do i breathe on it? - Land Rovers Only

scroth01 · 04-23-2008, 04:08 PM

I'm leaning towards purchasing a county but then i'd have the 3.9 to deal with and from the bit of experience i've had that motor is a dog(no offence!).
I'd like to know what i can do to freshen up a 4.2 before i swap it in....in terms of performance and durability.
I welcome any & all tips

carlosz · 04-23-2008, 05:27 PM

the 4.2 is a stroked 3.9 with the same piston bore, so technically you could take the pistons,rods and crank (crank journal size is a commom share amongst ALL rover/buick based engines) and dump it into the 3.9 block to convert it to 4.2 but by using the 3.9 you get a set of cross bolted mains which then lends it self to supercharging,turboing or other major powwer upgrades with out worries.
before the crossbolt, england attempted to build a turbodiesel v8 based on the old 3.5 but the compression ratio tore the threads out of the main caps on the block.
I guess they wanted to emulate the gm 6.2 which was a gas 350 converted to diesel and the compresion would tear thru the rod and main bearings locking the engine or throwing rods.
personally I would stroke a 3.9 just because of the cross bolt feature.

scroth01 · 04-23-2008, 06:38 PM

I hear you on stroking out the 3.9 but i kinda want to have the spare motor..that way the down time isn't too long.
but i could just replace the 4.2 internals with newer hi-po 3.9 parts right?,just where would i source that in the states?

57loboy · 04-24-2008, 01:00 PM

Buick 215 V8 = Rover V8... timing chain, distributor, intake for non-FI applications, there's probably more. Realize too though that because of the potential for head gasket failures, a lot of people use the newer 4.6s for big builds, but those are also big $$$.

carlosz · 04-25-2008, 05:25 PM

D&D fabrications = aluminumv8.com
they have a vast experience with this motors, I have obtained parts from them for the succesfull overhaul of two of my motors both 3.5's pushing close to 250 horse power at the flywheel running on regular fuel.
one of the motors I sold when I stripped my 87 due to rust. the other is about to hit 80,000 miles since overhaul. granted due to the extensive custom work it is getting worn out, stil has good compression but it rattles, no longer holds 10/30 oil I must use 10/40 plus a lucas at about every 1000 miles and if I floor it say to pass or to merge onto a ramp I leave a cloud of grayish blue smoke (worn piston rings and a very rich mixture).
visit their website and call them, speak to mark he is very knowledgeable and helpfull.

04-23-2008, 04:08 PM	#1 (permalink)
scroth01 Member Join Date: Apr 2008 Posts: 5 Gallery: 0	how do i breathe on it? I'm leaning towards purchasing a county but then i'd have the 3.9 to deal with and from the bit of experience i've had that motor is a dog(no offence!). I'd like to know what i can do to freshen up a 4.2 before i swap it in....in terms of performance and durability. I welcome any & all tips

04-23-2008, 06:38 PM	#3 (permalink)
scroth01 Member Join Date: Apr 2008 Posts: 5 Gallery: 0	thanks I hear you on stroking out the 3.9 but i kinda want to have the spare motor..that way the down time isn't too long. but i could just replace the 4.2 internals with newer hi-po 3.9 parts right?,just where would i source that in the states?

04-24-2008, 01:00 PM	#4 (permalink)
57loboy Senior Member Join Date: Sep 2007 Location: Newtown, CT Posts: 103 Gallery: 0	Buick 215 V8 = Rover V8... timing chain, distributor, intake for non-FI applications, there's probably more. Realize too though that because of the potential for head gasket failures, a lot of people use the newer 4.6s for big builds, but those are also big $$$. __________________ '95 RRC LWB, '05 Suburban Z71 (not stock), '94 F350 (only the cab shell & rear bumper is original), '62 International 404 tractor (red & white) & many other project cars in the past!

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04-23-2008, 05:27 PM	#2 (permalink)
carlosz Senior Member Join Date: Nov 2004 Posts: 107 Gallery: 0	the 4.2 is a stroked 3.9 with the same piston bore, so technically you could take the pistons,rods and crank (crank journal size is a commom share amongst ALL rover/buick based engines) and dump it into the 3.9 block to convert it to 4.2 but by using the 3.9 you get a set of cross bolted mains which then lends it self to supercharging,turboing or other major powwer upgrades with out worries. before the crossbolt, england attempted to build a turbodiesel v8 based on the old 3.5 but the compression ratio tore the threads out of the main caps on the block. I guess they wanted to emulate the gm 6.2 which was a gas 350 converted to diesel and the compresion would tear thru the rod and main bearings locking the engine or throwing rods. personally I would stroke a 3.9 just because of the cross bolt feature.

04-25-2008, 05:25 PM	#5 (permalink)
carlosz Senior Member Join Date: Nov 2004 Posts: 107 Gallery: 0	D&D fabrications = aluminumv8.com they have a vast experience with this motors, I have obtained parts from them for the succesfull overhaul of two of my motors both 3.5's pushing close to 250 horse power at the flywheel running on regular fuel. one of the motors I sold when I stripped my 87 due to rust. the other is about to hit 80,000 miles since overhaul. granted due to the extensive custom work it is getting worn out, stil has good compression but it rattles, no longer holds 10/30 oil I must use 10/40 plus a lucas at about every 1000 miles and if I floor it say to pass or to merge onto a ramp I leave a cloud of grayish blue smoke (worn piston rings and a very rich mixture). visit their website and call them, speak to mark he is very knowledgeable and helpfull.

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