zdmz Posted October 16, 2006 Share Posted October 16, 2006 Background: I have an early 74 260z with what I believe to be 73 round top carbs. They are the three screw stye. I ordered rebuild kits and they come with two needle valve housings, one is just about 1/8 inch longer than the other. In rebuilding the carbs I found that the front carb had the shorter valve and rear one had the longer valve. Is this correct or should they both be the same length??? Seems to me that they should be the same length as long as they floats are adjusted to the recomended 9/16" spacing. I did a search on the forums and found nothing and not reference was made in the rebuild kit instructions or in my cheesy manual. Quote Link to comment Share on other sites More sharing options...
X64v Posted October 17, 2006 Share Posted October 17, 2006 It's been a while since I rebuilt mine, but I remember them being different lengths. And the newest those carbs can be is '72. The 73 240's came with flat tops. Quote Link to comment Share on other sites More sharing options...
roninjiro Posted October 17, 2006 Share Posted October 17, 2006 Background: I have an early 74 260z with what I believe to be 73 round top carbs. They are the three screw stye. I ordered rebuild kits and they come with two needle valve housings, one is just about 1/8 inch longer than the other. In rebuilding the carbs I found that the front carb had the shorter valve and rear one had the longer valve. Is this correct or should they both be the same length??? Seems to me that they should be the same length as long as they floats are adjusted to the recomended 9/16" spacing. I did a search on the forums and found nothing and not reference was made in the rebuild kit instructions or in my cheesy manual. as far as the difference in size, yes it is normal. only the 71-72's had that setup, the 70 had equal valves. i had that same question earlier, and addressed it to ztherapy.com. they said it is completely normal, but i had a spare set of su's and made the setup i use with equal float tops (valves). as far as adjustment, i have no idea on those, i could never get mine running perfect b/c of this. that's just my preference though. Quote Link to comment Share on other sites More sharing options...
texasz Posted October 17, 2006 Share Posted October 17, 2006 Background: I have an early 74 260z with what I believe to be 73 round top carbs. They are the three screw stye. The '73 SUs were the flat-top not round-tops. The difference in the flat-top and round-top is VERY obvious, the flat-tops have a 90* angle at the top edge whereas the round-tops are...well...rounded. If you got round-tops off of a '73 car someone had swapped them at some point in the car's 33 year life...and this is a good thing as the flat-tops are worthless. Quote Link to comment Share on other sites More sharing options...
zdmz Posted October 18, 2006 Author Share Posted October 18, 2006 These are definantly round tops. If I recall correctly the round tops came in two versions - I think the earlier ones had four screw holding the piston dome on, later ones had three screws. Mine have three screws. I thought they started the flat tops in 74 - "missed by that much". Quote Link to comment Share on other sites More sharing options...
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