Prefect Posted September 27, 2020 Report Share Posted September 27, 2020 Could anyone kindly tell me the needle size for HS6 SUs for a TR4a standard engine. Quote Link to post Share on other sites
Drewmotty Posted September 27, 2020 Report Share Posted September 27, 2020 I think it’s a TW Quote Link to post Share on other sites
Prefect Posted September 27, 2020 Author Report Share Posted September 27, 2020 TW seems to be the concensus Many thanks for responding. Quote Link to post Share on other sites
tim hunt Posted October 1, 2020 Report Share Posted October 1, 2020 Yes, according to the Burlen/SU reference catalogue the standard needle for a UK TR4A is TW and QW for a US spec car. For a UK car one grade richer would be SW and one grade weaker C1W. When I fitted K & N high flow air filters many years ago the received wisdom was that I would need a richer needle to allow for the greater air flow. This was not the case, I retained the TWs and on a rolling road the car showed no unacceptable weakening at higher engine speeds. Tim Quote Link to post Share on other sites
BlueTR3A-5EKT Posted October 1, 2020 Report Share Posted October 1, 2020 (edited) The other thing to go for is the piston and damper. AUC8114 works a treat instead of the AUC8103 that may have been fitted. Peter W PS how to modify or check what you have fitted is here - plastic ones are easy as they have the part number moulded on them. https://mgaguru.com/mgtech/carbs/cb105.htm Edited October 1, 2020 by BlueTR3A-5EKT Quote Link to post Share on other sites
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