02-05-2022, 09:20 PM
Hi andrew
I find that even with SU and HC head, there is a critical gradient. Any steeper and you cannot sustain top gear. The revs progressively drop as you come down a little off the torque peak, and once you have dropped below about 2000 (30 MPH) a change down to 3rd is the only option. This then sends the revs up to 3400 due to the considerable gap between 3rd and top.
Although applying full gas can then sometimes push things back up to 4000 (35 MPH) it's hardly worth the extra commotion.
If I am carrying a passenger or the weekly groceries, one particular regularly tackled hill changes from "just get to the crest in top gear" to "change down halfway up" status. As you say, weight is critical.
Another long hill regularly tackled is just that bit gentler in gradient, and the Pearl can keep up 3000 RPM in top (44 MPH) all the way up.
I guess in the 1930s crawling up hills at 25 to 30 MPH didn't inconvenience anyone, there was probably a lorry just ahead going even slower !
I find that even with SU and HC head, there is a critical gradient. Any steeper and you cannot sustain top gear. The revs progressively drop as you come down a little off the torque peak, and once you have dropped below about 2000 (30 MPH) a change down to 3rd is the only option. This then sends the revs up to 3400 due to the considerable gap between 3rd and top.
Although applying full gas can then sometimes push things back up to 4000 (35 MPH) it's hardly worth the extra commotion.
If I am carrying a passenger or the weekly groceries, one particular regularly tackled hill changes from "just get to the crest in top gear" to "change down halfway up" status. As you say, weight is critical.
Another long hill regularly tackled is just that bit gentler in gradient, and the Pearl can keep up 3000 RPM in top (44 MPH) all the way up.
I guess in the 1930s crawling up hills at 25 to 30 MPH didn't inconvenience anyone, there was probably a lorry just ahead going even slower !