3.9l to 4.6l

[Bv8nc]

I bought a MGB V8 project car with a 3.9L Rover engine installed.  It loses oil pressure once it warms up due to worn main bearings.  (My mechanic has confirmed that both the oil pump and pressure relief valve are OK.)  As long as the engine has to come out I'd like to fit a 4.6L engine, but my reading seems to indicate there will be clearance issues with the 4.6 front cover and crank pulley. Can I fit my 3.9 (early style) cover and pulley to the 4.6?  If so, will any modifications be required? Are there better alternatives available?  Same basic question regarding the oil pan and oil pickup: clearance issues, interchangeability?

Thanks,
Mike

[mstemp]

Mike P,

You would need a different oil pan, pick up tube, timing cover etc to use the 4.6L. At least that was what I did 12 years ago. Since that time others have been able to fit the lower the motor and move it further back I believe to get it into position without steering rack interference.
Look at

http://www.britishv8.org/MG/JimStuart4.htm

for an example.

[Bv8nc]

Thanks Mike,

What I'm mainly wondering is if those pieces from my existing 3.9L engine will fit the 4.6L engine.

Mike

[mstemp]

Yes they can be used. You will need a spacer ring for the crank damper. Available from D&D and the wedge shop for $20.

[Bv8nc]

Thanks very much Mike.  That's what I thought I was reading, but some of the info was pretty vague.
Also good to know the sources for the spacer.

Mike

[Moderator]

Other than oil pressure, how do you like the 3.9? I don't think I'm the only one around here that would rather have a really well built/tuned/sorted 3.9 than an average 4.6.  Have you considered optimizing the engine you've got?