With the dramatically increasing engine power, I experienced lack of grip during hard accelerations. The tyres was just spinning and on a prepared 1/8mile strip the rear axle was tramping.
I new wider wheels was part of the answer. The other part is the rear axle suspension. The rear suspension of the classic Morgan is by semi-elliptic leaf springs. The rear dampers was original ‘Armstrong’ lever type. These I converted to telescopic shock absorbent in 2001.
The tramping problem seems to come from wind up of the the balder springs during hard acceleration.
I decided to make a rear axle motion test setup. The two pictures below shows some of the test results. Even the spring system is very stiff it indicated some 5-7 mm backwards move of the rear axle during acceleration.
I hoped the answer is ‘anti-tramp’ bars.

The ‘anti-tramp’ bars need, ideally, to form a parallelogram, when viewed from the side, between the front spring eye and the center of the axle thus allowing the axle to rise and fall without any spring wind-up but allowing sufficient axial rotation such that the axle is not disturbed by body roll. Because the shackles are at the rear it is normal to run these bars forward to the cross member which supports the front spring eyes.
Not much space was available and I had to mover the catch tank and break pipes. Lag of space also meant use of squared tubes for the bars.

The results of the efforts has been tested on a Raceway prepared with Track Bite. The wider tires gave much better grip and almost no tramping was experienced during take off.