HS8 question.

Technical advice Q&A
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genneton4
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#1 HS8 question.

Post by genneton4 » Mon Apr 01, 2024 8:06 am

Hello. I wondered if I could ask a question about an XK120 here for the E type oracles. ?

I have an E type going very well but am currently tinkering with the XK120.

I have fitted 2" HS8 carbs 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
Present - Series 1.5 FHC 1968, Opalescent Silver Grey - Illinois car.
2009 - Series 1 FHC 3.8 1963, Opalescent Maroon - Dutch ex USA car used in France.
1995 - Series 1 FHC 3.8 1962, Carmen red - from E Type Centre as was.

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mgcjag
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#2 Re: HS8 question.

Post by mgcjag » Mon Apr 01, 2024 8:30 am

Hi Keith...JagLovers has a very good XK forum.. Steve https://forums.jag-lovers.com/c/xk/28
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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abowie
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#3 Re: HS8 question.

Post by abowie » Mon Apr 01, 2024 1:05 pm

genneton4 wrote:
Mon Apr 01, 2024 8:06 am

Is there any way I can dig myself out of this hole. ? Maybe retard the ignition a tad ? Different needles ?
There's not really an easy subjective answer to this.

I fitted a 4.2 engine to my Mk2 with the same double HS8 XJ6 setup that you have.

I then had the car tuned on a rolling road dyno. I think that this would be your best option too.
Andrew.
881824, 1E21538. 889457. 1961 4.3l Mk2. 1975 XJS. 1962 MGB
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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