I'm finishing a replacement N42 head plus a retune of my existing SUs. Got a great deal on another set of SUs plus intake and am debating having them bored out and dropped on my refreshed top end motor. I'm really debating breaking down and getting a set of triple Mikunis but the bored out SUs seem like a better deal in terms of cost, reliability and ease of tunability. Engine is an L-28 with an N42 head, a Schneider street cam and a header. It's a street car with an occasional run to the track for HPDE/autocross.

Anyone have big bore SUs? How do you like them? Any tricks to tuning them? Should I have the machine work done then buy the Ztherapy rebuild kit or vice-versa?

Getting more responses over on hybridz.org, here's a link for anyone who's interested.

http://forums.hybridz.org/showthread.php?p=860436#post860436

Members of both honoring the difference in content between Hybridz and ClassicZCars!

Thanks for the link! I always thought the modified needle profile would be easy to change, but difficult to figure. I envisioned tuning the profile with a series of precision nested tubes relieved at the butt end and jigged through a mount to knurled movements, and then using the lathe to make the actual needle.

Will

If I go the big bore route, I'll be asking John Williams in Atlanta to do the mod. I'm going to ask him if he would grind the needles to get what he wanted from the carbs.