If you know nothing about B20 Volvos and SU's, then spending thousands of dollars running on a dyno would be the way to go, BUT, with experience comes knowledge.

Generally, a B18B or B20B runs perfectly with KD/KN needles in Twin HS6 SU's and BBB works perfectly in Twin HIF6 SU's. You could use C, D, K, VPD Street or equivalent, the trick is to keep the cam similar to standard and make sure the piston does not run out of travel. Basically with SU's, if you draw in 'X' amount of air through the bridge of the SU, the piston raises up by 'Y' and fuel flows out accordingly. Same as K-Jet in a way, if you are lucky enough to have K-Jet, you can make some fairly drastic engine mods and there is no need to change anything.

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69 142S Overdrive + 69 164S Manual