Thread: 4.2 rover v8

I acquired one with the old 2 door that became my ute. Sold it to a friend of mine with an '87 RRC auto. He loves the extra torque, he uses it to tow his boat and take his kids off road. The '87 is otherwise totally original mechanicals and has been going over 3 years with the 4.2 fitted. It does not get driven at high revs, there's no benefit with the stock EFI.

The only thing I'll say about it is that it sounds somewhat piston slappy as it has short skirt pistons (I did look up its skirts with the sump off, purely for academic interest.)

Originally Posted by bee utey

I acquired one with the old 2 door that became my ute. Sold it to a friend of mine with an '87 RRC auto. He loves the extra torque, he uses it to tow his boat and take his kids off road. The '87 is otherwise totally original mechanicals and has been going over 3 years with the 4.2 fitted. It does not get driven at high revs, there's no benefit with the stock EFI.

The only thing I'll say about it is that it sounds somewhat piston slappy as it has short skirt pistons (I did look up its skirts with the sump off, purely for academic interest.)

Thanks, I have just acquired a John Davis built one with a piston and liner damaged, has the john Davis fuel ECU upgrade, the big H&M headers, head porting/ matching and a few other goodies. Thinking of stripping it down and rebuilding it possibly with another block if the liner damage is too severe where it got dragged down into the crankcase an inch

JC

Originally Posted by justinc

has anyone here got / had one? specifically the one using 3.5 litre bores and the stroker crank/ rods etc.
would like to hear about its performance and reliability.
jc

I think I have one haven't had to take the heads off in the almost 4 years I've owned it. but it had stroker embossed on one of the counterweights & was told its a 4.2. so i have no reason to doubt it.

reliability wise, I've had no problems with the motor until I started playing with it, replaced the cam, lifters, timing chain etc. and have had low oil pressure problems not long after.
If the planets align and I have enough spare cash it will be getting rebuilt this year. compression is down, its starting to get smokey on start up & its getting a bit tired.

Performance wise, it seems to go ok (however I have no previous RR knowledge to compare it too) some usable power and fair bit of torque but as with all engine it could use more. responded well to the cam swap and converting to efi.

on a trip to NT it was cruising well at 130 and got to 145-150 easily enough (when overtaking road trains etc) I was on small tyres (~29-30" - i think). I haven't taken it on many rock tracks as not much around here local just sand & mud (broke the rear diff- the first time out on rock - chalked it up to inexperience in a 4x4), but it loves the sand, Stockon beach most big dunes where low 3-4, some in high range (r380+LT230) and no issues getting into 5 rocks

did the piston nip up?(slight understatement)

Originally Posted by justinc

Thanks, I have just acquired a John Davis built one with a piston and liner damaged, has the john Davis fuel ECU upgrade, the big H&M headers, head porting/ matching and a few other goodies. Thinking of stripping it down and rebuilding it possibly with another block if the liner damage is too severe where it got dragged down into the crankcase an inch

JC

G`day ,

if you measure a piston , i think you`ll find it`s oversize from std 3.5 so it has to be bored and then there is a chance of the loss of what the 3.5 does best ( not move liners )

I would guess the one you have has broken the skirt and if you peruse the others there is a likelyhood you`ll find skirt cracks . ( didn`t read your last line so it may have more than a skirt problem )

New set of omega pistons even to you is probably over $1000 . ACL make them so even though they appear to be UK they are actually AU .

If running flapper , either the ECU from a UK vehicle or a particular Jag ( don`t remember ) will overcome any full throttle fueling problems .

Seems from new as in built they will give around 200/250kms before they break , some just blow a bit of smoke , some self destruct .

Driven one a few times infront of a ZF and it`s disappointing in comparision with either the 4.0 Tflite of our 84/5 or 3.9 ZF 94/5 though never towed with it .


Peter

Did the conversion to my '83 back around 94.

With the last 4 spd box and its diffs it was great. Would idle up some of the steepest off road climbs around the place. Recall the first time I actually used it in anger overtaking a couple of semis on the old Hume up a hill Nth of Aubury on a short OT lane. Case of select 3rd and floor it, after passing, and when I looked down it was up around 90+mph.

Could also chirp tyres in second if not careful.

Loved that truck!

Part of the kit I received at the time included a bigger oil pump, wider gears and a spacer as I recall. The extra bit of crank made massive torque. Recall having to file out part of the crankcase casting at the bottom of the cylinders to get crank rotation.

Was still running extremely well when it went in 97 for a Disco oil burner.

Cheers

RF

so, did any of these 4.2 engines actually use 3.5 pistons? or were all special omega ones as well as rods and crank? i haven't stripped it yet so haven't seen them to compare.

jc

You might have to correct me but a bloke I used to know built rover V8's with Volvo pistons that had floating pins that fixed the broken skirt problem. Pat