Series V Readend

[RootesRacer]

i pulled out a couple of my H120 dealer literature and both show a 3:89 rear end gear. 1st gear ratio was 12.14:1, 2nd was 7.75:1, 3rd was 5.04:1 (OD 3rd 4.05:1), 4th 3:89 (OD 4th 3.12:1) i wonder where the name H120 came from?

IIRC it was Holbay 120hp.
At release it was 105hp, they didnt change the name.

From what I gathered years ago speaking with some folks at Holbay while they were still solvent, the E128 cam was the specification that the H120 was supposed to have had. This is a far more conventional "symmetrical lobe" cam, where the engine made gobs of horsepower, with a rather predicable bottom end.

The actual H120 cam defies description, required some very odd tuning and attained some level of horsepower while not giving anything up down below.
Perfect for early 70s rallies I suppose.

 

[65beam]

rear end

every thing that i have lists them at 110 hp @ 5200 rpm.that's why i wonder where the 120 comes from.

 

[RootesRooter]

As RootesRacer posted, the H120 supposedly penciled out to 120hp with the hotter cam, plus the intake ports were supposed to be the same size as on Series V's. It ran too rough for a family coupe so they narrowed the intakes and swapped cams. 105hp was the final result - but "120" sounded so much better. Of course, those were still the 'olden days' of theoretical horsepower calculation. Like the Tiger 260's claimed 164hp (really 139hp), our Rootes-powered Sunbeams probably didn't measure up to the sales brochure specs either.