JCan

Thanks! When I started restoring the Z, I was amazed at the knowledge base I found on this and other sites. As I find information not covered, I'll post it. Long live the HybridZ database! HAHA Jim

Topic - This note discusses the advantages of heating SU carburetors and provides a source to purchase a new Manifold Heat control thermostat. __________________________________________________ I'm Jim and am restoring a 72 240z with my 15 yr old son. As this project is designed to teach my son how cars work we chose to use SU carburetors and had the great folks at ZTherapy restore our old carbs for us (they did a great job by the way). SU carbs are fantastic! The simple design delivers a nearly constant air/fuel mixture over a wide RPM range and are easy to adjust (once you know how). This design does have an issue, however. The air/fuel ratio delivered by this and other types of carbs is a function of temperature. To solve this problem, Datsun uses engine coolant to heat the SUs therefore greatly improving Air/Fuel mixture consistency over operating temperature and as a side benefit improves atomization of the gas (parafrased from Nissan Service Manual page EC13). In a '72 240z (referring to the attached schematic attached) Nissan Engineers take hot water just below the engine thermostat (when closed ie startup this is a high pressure ) the water is run into the left side of the intake manifold, touching the carburetors then out the right side of the manifold to a manifold thermostat then around the back of the motor to the input / low side of the engine water pump. The manifold thermostat is normally open and monitors the temperature. At ~140 degrees a valve inside starts to close and closes completely at ~150 degrees. Unfortunately, in the blogs and in person most people have the manifold heater disabled. Its no wonder, after 40 years the plumbing gets clogged and the thermostat stops working thus causing poor running conditions. Last night, after looking for a thermostatic control valve for this application, I found two! the first was too expensive, however the second from Therm-omega-tech in the midwest, sold me one for $100 (http://www.thermomegatech.com, P/N 213-000000-140 Data sheet TVHAT attached below)! TVHAT.pdf I know $100 is a lot to pay for this functionality so I have three alternative implementations that are less expensive and should provide the same results: Look for the original thermostat on craigs list and rebuild that (drawing below). Ebay sells 12V solenoid valves for $<20 and you can purchase a thermostat switch for <$10 which would most-likely work (however I worry about how long it will last). Purchase a simple hand valve for <$20 and you can turn it on in the winter when you need it! Brian and I have almost completed the assembly of the motor, however we have not started assembling parts onto the newly stripped and painted body. Once we get the car running, I will measure temperatures and post them here (most-likely in March 2013. I welcome comments, Thanks! Jim

Hello I am happy to help! I also have had the issue of what to do with the broken spring on my '73 240z. This week I was rummaging for parts and found a wiper motor which was intact without the spring being broken! Needless to say I disassembled it and have an answer for you. The first picture shows the order of the parts as they go onto the wiper motor. Please note the spring. It wraps round the offest cam and is keyed with a portion of the spring directed through the hole on the washer plate see pictures two and three. I believe the use of the spring is to help turn the cam clockwise and counter clockwise while allowing the cam to move free when the windshield wipers are pulled by gas station attendants. good luck with your repair! Jim