Welcome to our Site for MG, Triumph and Austin-Healey Car Information.


MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB GT V8 Factory Originals Technical - Aussie V8ers

Sorrt to be so narrow but this question is squarely aimed at aussie v8ers.
Having once owned a chrome bumper v8 (rover motor of course)
I now have the bug again
Alas I have a 1980 GT which needs TLC and i also went thru my shed and have an old holden 4.2v8 in good nick
Whats the likely weight and dimensions of such a motor.
If the weight issue isnt that bad, Yella Terra have aluminium heads for these motors which could free up another 30 - 60 pounds
But if the dimensions are too big,wide etc etc then its back to the buying a rover motor
Look forward to any replies


I don't know just off hand but I will post a request here:
for the details since I am also curious.

This is a local performance oriented board with a lot of experienced and very knowledgable posters.
Membership is free and there is no spam either!

The 4.2 is a much overlooked engine in my opinion and most people go directly for the 304 (5 litre).
By the way there was a series of "hot up how to's" for the 253 in Performnace Buildups recently and I believe Rare Spares are also a good source for bits and pieces.

I'kll post an answer as soon as I have one.

Cheers, Pete.
Peter Thomas

Peter your right
The 4.2 is very much overlooked,it isnt as bad as people think it is alhough i read somewhere about the siamese ports etc,
But there are a lot of bolt on bits for it and some people are giving these motors away, a genuine 300bhp is easily achieved
Look forward to your reply



Sorry but no joy on the weight of the 4.2 V8.

A couple of suggestions if I may...

1) With a beam and pivot you can determine the weight with a set of domestic bathroom scales by using reverse leverage (say 10:1.)

2) The Caslemaine Rod Shop may be able to help with the weight and also they have a large range of conversion orientated accessories like bell hoiusings to mate 4.2 Holden V8 to Toyota gearboxes and the like.
The link is:

3) I am not sure how close in measurements the 4.2 and the 5 ltr engines are but the Rod Shop should be able to tell you. This may be useful as a guide.

4) From what I have been able to determine the 4.2 V8 is smooth, economical and virtually unburstable. Soundls like a good choice for the conversion.

Good luck,
Cheers, Pete.

Peter Thomas

Steve, 4.2 GM motor bit heavier than ROVER &WIDER
Stephen Foldhazy

[ i didn't finish] try P76 v8 4.4litre motor as was quicker than HQ 4.2; or better use Rover block as easier to fit & many parts available to make 5.2 litre. Steve
Stephen Foldhazy

Thanks Peter
ill ring the rodshop during the week
And to steve
i though the Holden 4.2 litre was a 90 degree v8?
I knew the motor would be heavier than a rover but remember you can get alloy heads for the 4.2.
Albeit we dont know what the original weight and size are and thus the weight saving could be valuable or a complete waste of time
Tell us more about the p76 motor..

STEVE.Rover v8 is about 365lbs & Holden v8 about 500lbs.See Adrian at M.G. Adelaide workshop at 224 Kensington Rd, Marryatville.5068 ph83644988 for all your M.G & v8 bits & performance parts.He's built a few quick V8 M.G.s using Rover v8s. tell him 'hi 'from me.Steve
Stephen Foldhazy

I've always liked the 'P76 motor, I feel they substancialy improved the Rover 3.5 motor. They stroked it to 4.4 by making the block a little taller. I have not heard of any problems with it however I only briefly looked into it as a possibility. The main reason why I rejected it is I wanted to use fuel injection (economy/power)and I though the extra half inch (I don't have exact figures)might be a problem. There is also the fact that the P76 is a car of the '70's and I thought parts might be a problem. I believe that the Block,Crank, flywheel and rods are uniquely P76 while the rest can be substituted for Rover.
I know a guy who bought an entire P76 (with manual gearbox, good motor,Holly carb')for about 1200 (the motors are worth more than the cars, go figure) and did a straight transplant. Easy, he sez..If you came acroos somthing like that it would be difficult to say no I think.


Contact Leyland p76 Club in your state for any parts, still easy to obtain parts & cheaper than Rover engine parts. I have P76 as tow car for my Historic racer MGCGT, They still great touring cars & equal of any late model Dunnydore or AU ford which i have to drive for work so can do comparisons. STEVE
Stephen Foldhazy

This thread was discussed between 03/12/2002 and 22/12/2002

MG MGB GT V8 Factory Originals Technical index

This thread is from the archives. Join the live MG MGB GT V8 Factory Originals Technical BBS now