Peter Richards' 1979 MGB-LE with Rover 3.5L V8
(originally published in British V8 Newsletter, Volume 5 Issue 1)
Owner: Peter Richards
City: King City, Ontario, Canada
Model: 1979 MG MGB-LE
Engine: Rover 3.5L V8
I have finished, after two years, a well-sorted MGB conversion to the 3.5 litre aluminum Rover V8. The conversion is based on a rust free '79 MGB-LE body with a genuine 78M Km on the speedo. I have retained the original 4-speed transmission with overdrive, and have experienced no problems with this combination (except for an increased pedal travel over standard to disengage the V8 clutch.) I have also fitted the 3.07 rear end gear ratio which makes for a better performing combination than the original 3.9 ratio. The conversion was undertaken using adapter parts from British Parts Direct in California and M&G International UK.
How It Was Done
|Engine:||1970 Rover V8 P6, blueprinted and balanced.
V8 headers into a 4 into 2 into 1 custom made exhaust system.
Stock V8 camshaft.
MG V8 aluminum valve covers.
|Ignition:||stock V8, set at 15 degrees BTDC at 1000rpm with idle at 800rpm.
|Fuel:||Holley 390cfm carburetor with the following modifications:
"Green" fuel shot cam,
softest "Yellow" secondaries spring opening at 3200rpm,
recalibrated main jets down from 52 to 49.
Holley fuel pump set at 7psi.
JWR Offenhauser dual port manifold.
|Body:||stock, except for 15x7 rims fitted with 205/60 x 15 BF Goodrich tires,
telescopic shock conversion fitted at rear. V8 bushings.
Upon fully completing the installation of the V8, the front suspension settled a full half inch
higher in front than before This was brought backto a slightly lower than stock position by
fitting a set of Moss one inch lower front springs.
My next experience after initial engine start up was an overheating condition on anything beyond a one minute idle. No problem though, when under normal driving conditions. Having double checked that the dynamic timing was set as prescribed by the manual, I resorted to increasing the airflow through the engine compartment. I decided to fit an MGC hood with the small tear drop bubble machined flush with the C's main hood bulge lines, and a dual row of louvers positioned two thirds the length of the MGC hood. This improved somewhat the overheating problem. The C hood also allowing a larger air cleaner to be fitted.
With the modified hood installed, overheating during idle now took four minutes instead of one. The temperature would return to normal within a few minutes of driving. Liveable, but not satisfactory. I then read in a UK classic magazine of a situation whereby an overheating condition was cured by advancing the engine to a greater than the referenced setting stated in the owner's manual. The V8 manual I have prescribes 6 degrees BTDC timing at 800 rpm. I have now set this at 15 degrees, at 1000 rpm (dynamic strobe setting.) Idle remains at 800 rpm. With this timing change and the other modifications. The overheating problem has nearly disappeared altogether. I am aware of the problems caused by over-retardation or advance of the ignition timing, but I am puzzled as to why the manual would say 6 degree BTDC and yet setting the timing to 15 degrees BTDC would have this positive effect. Overall engine performance has not been noticeably different with the exception that it now runs and idles at near normal temperatures. The only other tuning changes made were those described above for the Holley carburetor. That is changing the fuel shot cam to "Green" to cure a hesitation on acceleration from a cruise condition and reducing the main jet size from 52 to 49 to cure an initially overly rich fuel mixture setting. Today the car performs extremely well.
I have recently stocked, for future use, a Mallory Unilite distributor and a 216 degree at 0.050 Crane cam (with new lifters of course). I would be interested if any of the Newsletter readers have had experience to fitting these and what to look out for in the process.
The MGBV8 is in very good condition with well looked after original black paint. In Summer '92, I was pleasantly surprised when the car was awarded a first place in the "Best Modified" class at the MG Car Club of Toronto's Tire Kicker Show.