Author Topic: A65 Lightning carburettors  (Read 534 times)

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Bess

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A65 Lightning carburettors
« on: 08 March, 2017, 12:58:11 »
Hi all,
         I am the point where I need to buy carbs. Machine 1, is Oct 1968, 9:1 pistons with a  twin carb head. The other is Aug/Sept 1968  single carb head with 9:1 pistons (Thanks JulianJ for dating). Both heads have 1.598 inlet and 1.410 exhaust valve diameters.

I have looked at the manuals and services sheets and I not sure which would be the best carbs to buy, jets and settings I should adopt as I am sure I haven't got all the information. I am also aware that as time went on BSA improved fuel delivery.

Any spark plug advice would aslo be appreciated.

Best wishes.....

Arthur

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Re: A65 Lightning carburettors
« Reply #1 on: 08 March, 2017, 17:36:26 »
Data listed for your 1968+ engines with those valve sizes and compression ratio are:

Lightning

930/34 + 930/35
main:         180
Needle jet:  106
slide:          3.0 cutaway
pilot:          20

Thunderbolt

928/6
main:         230
Needle jet:  106
slide:          3.5 cutaway
pilot:          20


Bess

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Re: A65 Lightning carburettors
« Reply #2 on: 08 March, 2017, 20:28:49 »
Thanks again Arthur.

Best wishes...