Replace HD6 with HS8 Dilemma

XK
1

Hello. I am tinkering with a '53 XK120 SE OTS. I was ‘encouraged’ to fit 2" HS8’s and I am disappointed with the low down torque (ie off the line power) they have delivered. They are quite a bit better higher up the rev range but I really wanted to improve the off the line power.

It is a 3.4 with an SE head (not C type), both inlet ports reamed to 2". The engine was rebuilt 1000 miles ago. I have trumpets with foam covers. The needles are standard XJ6 BAW. Powerspark ignition.

Is there any way I can dig myself out of this hole. ? Maybe retard the ignition a tad ? Different needles ?

Any wisdoms gratefully received.

Keith

2

First isolate it to being mixture and tune it richer, trial run, if it is worse go leaner.
Then either try other needles or measure and file them to suit, I guess.
You know the mintylamb.co.uk website?

3

Actually this is useless, a standard 3.4 with standard head will not gain from going to HS8 carbs.
The only gain you get is higher fuel consumption.

2 Likes
4

Hi there:

This is quite true: the breathing ability of the inlet/head is the limit, not the carbs in this case.

Best,

Ll.

5

Yes… go back to the original carbs: they are MORE than adequate for that car.