Guest rick458 Posted August 5, 2003 Share Posted August 5, 2003 Gentlemen; My 260 with flat tops has the water cooling tubing bypassed by PO it never gets very cold around here (Houston Texas) so does the radiator water help or hurt vaporlock on these carbs I still have not driven it on the road but will be soon and DO NOT want to get vapor locked away from the house Quote Link to comment Share on other sites More sharing options...
Guest Al 260Z Posted August 5, 2003 Share Posted August 5, 2003 260Z has three carb related cooling loops: intake manifold base, crossover (balance) tube for EGR, and carb base. I think the intake manifold and carb base are primarily for warming to reduce emmissions and improve driveability upon cold start, while the balance tube line is undoubtedly for cooling. I'd definitely keep that one. While my performance-head motor machinist is dead-set against warming of air intakes, I'd recommend keeping these, too. It'll assure more consistant operation and will be a gaurantee against raw fuel droplet injestion into engine, and carburetor icing in cool damp weather. I've got all three lines hooked up although with my DGVs, the carb line goes to the base of the DGV gooseneck intake adapter, not to the carb itself. It is plenty hot here in summer in North Calif. The chief disadvantage of all these lines is they make for lots of possible coolant leak locations. I keep some extra hose and plug options handy just in case. I replaced all the hoses with OEM some years ago and lately noticed they are getting hard and cracked ends. I may eventually try to fit up a set of silicone race-grade hoses from Pegasus (http://www.pegasusautoracing.com) for all these gizzies, or else see if Nissan still stocks replacments. Warm restart trouble was one of the chief problems with the Flat-tops, but it's often an issue with SUs and 280Z FI also. Note the special air fan for fuel rail cooling on ZX's. Nissan called the problem "heat soak". It is the reason for the electric fuel pump on 73-74 Zs and for the hood vents they added starting with the 75 280Z. Unlike most folks I'm a fanatic about minimizing head/valve warpage and heat soak trouble. I always idle-down for a minute or more after coming off the freeway. And I pop the hood to let 'er cool down as much as possible. If I'm not in a dubious neighboorhood, I'll leave the hood up. I hate the thought of all the engine hoses, belts, wires, gaskets, etc. baking away from exhaust manifold heat with nowhere to go. And... I've never had a warm restart problem. Later, Al Quote Link to comment Share on other sites More sharing options...
Guest rick458 Posted August 5, 2003 Share Posted August 5, 2003 The Manifold and Balance tube water are still connected it is just the carbs bypassed the distribution block thing behind the motor feeds the intake but the carb line currently jumps over the top of the motor to the water pump. it gets mighty hot in the engine bay just running in the garage does anybody make louvered wing panels (or what ever the little doors are called) for a 240/260Z [edited] found them MSA makes them and a louvered hood Quote Link to comment Share on other sites More sharing options...
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