3.9 OR 3.5 V8

[R6RY D]

Help needed, i have a spare v8 rover, i was planning to spice up and put in my range rover, but i have gone to get the edngine no of it (on the casting by dipstick) and theres nothing there? i found these numbers on the left side of the block, just under the head. ht22619?? Then to confuse a little more i noticed the heads have blanks just next to the exhaust ports. where as the ones in my bog 3.5efi dont, i was of the impression that my spare lump was a 3.5 efi, could anyone shed some light?

[andys2]

The blanks on the exhaust ports sound like the old pulse air system, which would indicate that it is an early 3.5. The best way to check would be to take one of the heads off and measure the bore.

HTH

Andy

[wedg1e]

Whilst the bore size will tell you if it's a 3.5 or 3.9, you also need to know the valve sizes. The earlier heads ran smaller diameter valves, 38mm inlet and 33mm exhaust. After the SD1 appeared, in 1976, the valves were increased to 40mm inlet/ 34mm exhaust.
Quick way to tell without lifting the heads is to measure the reach of the sparkplugs: early heads used 12mm and post-76 use 19mm reach plugs.
The heads with the smaller valves will provide a major obstacle to increasing power output.

[R6RY D]

thanks for the help chaps