Nealio240z Posted July 25, 2006 Share Posted July 25, 2006 My Z is running like a dog... (sbc carbed 350) Ill drive it for a few miles and it will cut out on me and die... There is ALOT of heat in the engine compartment. I poured some water on the inner fenderwell near my fuel pump, and it boils the water... I have a sheild between the fuel lines and the headers, but it still over heats the lines... Im guessing that the gas is boiling in the lines, and the fuel pump hits the air pocket and it kills the motor... If I let it sit for a while or cool it down with water, it will run fine. What could I do to solve this problem? If thats the problem. I dont have a fuel return line, and im running only 5 psi, (soon to be replaced with a 7-10 psi unit)... How do I lower my engine bay temp? Or fix the problem? ****ALSO my temp guage says that it is running @ 210-240 degrees. Im using the stock 240 sending unit and guage. Is this normal? What should it read? Is it hot because the sending unit is next to the headers? Is it running hot, or is it giving me a false reading? What is the solution.. I really need help with this... Its keeping me off the road.. Thanks... Quote Link to comment Share on other sites More sharing options...
Bartman Posted July 25, 2006 Share Posted July 25, 2006 What fuel pump are you using? Can you move your fuel pump closer to the tank? Most fuel pumps are designed more for pushing fuel rather than pulling it. A return line could help as well, but I think relocating your fuel pump would be the best solution. Quote Link to comment Share on other sites More sharing options...
deja Posted July 25, 2006 Share Posted July 25, 2006 ALSO my temp guage says that it is running @ 210-240 degrees. Im using the stock 240 sending unit and guage. Is this normal? What should it read? Is it hot because the sending unit is next to the headers? Is it running hot, or is it giving me a false reading? That is way too high. What radiator are you using? Does your engine have a thermostat and is it working? Are you running a fan? I run a stock Datsun radiator and an electric fan on a temp switch. Even wtih that relitivly small radiator as long as I'm moving the temp never sits right at 180. The fan kicks on when I stop moving when the temp get to 210. Quote Link to comment Share on other sites More sharing options...
Nealio240z Posted July 25, 2006 Author Share Posted July 25, 2006 Im using an aftermarket electric fuel pump, at about 5 psi... I dont know the brand... Quote Link to comment Share on other sites More sharing options...
Nealio240z Posted July 25, 2006 Author Share Posted July 25, 2006 Deja... Im using a 4 core copper radiator, Duel electric fans (pushers), and a 190 degree thermostat... Is the guage wrong? Or the sending unit? Is the headers heating up my temp sensor? It is screwed in between the 1 and 3 cylinders... I really need any suggestions... Quote Link to comment Share on other sites More sharing options...
deja Posted July 25, 2006 Share Posted July 25, 2006 You said you have a carbed engine move the temp sending unit to the intake manifold, there should be two fittings there. The headers can fry anything. The guage could be wrong but I'm running a stock gauge with no problems Quote Link to comment Share on other sites More sharing options...
Nealio240z Posted July 25, 2006 Author Share Posted July 25, 2006 Will it screw into the chevy manifold? Would the header heat make the unit that hot? What temp should the z run normally? Quote Link to comment Share on other sites More sharing options...
deja Posted July 26, 2006 Share Posted July 26, 2006 Will it screw into the chevy manifold? Would the header heat make the unit that hot? What temp should the z run normally? Depends on you intake but mine does, a stock chevy sender certainly will. Like I said I run about 180 as long as the car is moving and about 210 if I'm sitting in traffic, the fan rarely comes on, its controlled by a temp switch mounted on the fitting on top of the water pump. Quote Link to comment Share on other sites More sharing options...
DavyZ Posted July 26, 2006 Share Posted July 26, 2006 You'll also notice that deja is running a very good electric fan, not a pusher AND a shroud (important!) that covers nearly the entire area of the radiator. Those two things are key. Pusher fans are not nearly as desirable. Your thermostat seems to be the right temperature, but you could also go lower as well to open up sooner. Do the fans run constantly? If they do and you are still overheating, they might not be up to the job. Also, you live in Redding! With the recent heat wave, you must be seeing temps around 110 degrees outside. Any weakness in your cooling system will rear its ugly head. Is your radiator clean inside (no sludge or other crap that another owner could have put in there)? Did you purge the system of all the air???? Air pockets can cause problems. Typically, you purge the highest point in the system...air goes up... Burp that baby. Davy Quote Link to comment Share on other sites More sharing options...
deja Posted July 26, 2006 Share Posted July 26, 2006 And don't just assume the thermostst is working. If its old it may be dead, Its a cheap part, just get a new one. Quote Link to comment Share on other sites More sharing options...
Bowtiez Posted July 26, 2006 Share Posted July 26, 2006 Add a clear fuel filter and you can actually see the air bubbles causing your problem. 1) Make sure the fuel tank is properly vented. I trashed the factory unit. 2) Rubber mount an electric fuel pump to the outside of the spare tire housing next to the fuel tank. I had a new 1/2 pickup line installed by a radiator shop at the rear of the tank for racing but it does interfere with the fuel guage sending unit. Depending on the carb, a regulator may be needed even for 7PSI. 5 PSI is fine for most street applications. Remember fuel volume is what is needed when you are running flat out. 3) The stock Z is about a 5/16 line. Replace with either 3/8 to 1/2 inch line running over the mustache bar and rear down the top center of the tunnel above the transmission and exiting to the passenger side of the hood latch. Add a filter and pressure guage on a braided line between the hood latch. Be sure to keep it away from the heater hose lines. 4) Use a 195 degree thermostat. Sounds stupid but my calls to Perma Cool indicated that a 195 thermostat will maintain a more consistent temperature better than a 180. 5) Cooling problems completely disappeared when I changed from the Scarab style to the JTR kit. I am using a Griffin alumininum radiator with a single puller fan and homemade fan shroud. I added a new water wetter product that to replace antifreeze that drops the temp 15-20 degrees. 6) I also have old school functional louvers on the hood and inspection panels Quote Link to comment Share on other sites More sharing options...
Paz8 Posted July 26, 2006 Share Posted July 26, 2006 Deja also is running cast iron exhaust manifolds which helps to keep down the temp under the hood, just my observation. Quote Link to comment Share on other sites More sharing options...
Bowtiez Posted July 26, 2006 Share Posted July 26, 2006 Deja also is running cast iron exhaust manifolds which helps to keep down the temp under the hood, just my observation. True, but they suck for power and weight. My old flow tech headers were wrapped and that helped, but it is hard on headers. I did not wrap my new Sanderson ceramic headers and the temperature under the hood (and on my feet) is obviously hotter. Part of the heat was due to the increase from 330 horsepower with a 100 shot of N2O (engine blown at the strip) to about 450 horsepower without the bottle now. Quote Link to comment Share on other sites More sharing options...
deja Posted July 26, 2006 Share Posted July 26, 2006 Deja also is running cast iron exhaust manifolds which helps to keep down the temp under the hood, just my observation. Yes I am, the headers that came on the car were trash and I don’t like headers on the street for the heat, noise and leaking reasons. Yeah, the manifolds did take some power away since this engine isn't a stock setup but my car is a daily driver, not a racer. I am running those old school functional vented louvers on the hood, I think they allow more air to flow though the engine compartment. You can't pull air through the radiator is it can't exit the engine compartment easily. Quote Link to comment Share on other sites More sharing options...
Nealio240z Posted July 26, 2006 Author Share Posted July 26, 2006 The radiator was just flushed, the thermostat is brand new... I will try the duel fans (pullers) and a shroud. I think is just showed that it was running hot, because the temp sensor was between the 1 and 3 cyl... But i dont want to take any chances.... I also have the functional fiberglass hood loovers (backward scoops) you can see the heat leave. Will the 5 psi fuel pump do the job or do I need a bigger unit? It feeds a Q-jet 750 cfm. Will it starve at high rpm? Quote Link to comment Share on other sites More sharing options...
Paz8 Posted July 26, 2006 Share Posted July 26, 2006 I don't think there is a really big difference in street performance between a "block hugger" header and a cast iron factory manifold, a full length header yes big difference, the rest of the exhaust system to the back of the car is more important in street applications. Quote Link to comment Share on other sites More sharing options...
Bowtiez Posted July 27, 2006 Share Posted July 27, 2006 I don't think there is a really big difference in street performance between a "block hugger" header and a cast iron factory manifold, a full length header yes big difference, the rest of the exhaust system to the back of the car is more important in street applications. Not to jack this thread, I agree you do not get the scavenging effect as much as full length headers but I have yet to find a header still made that will fit the JTR conversion. I agree the rest of the system is important. My Sanderson 1 5/8" headers flow smoothly into my mandrel bent connecting pipes to collectors to 2 1/2 inch side exhausts for racing. Block off plates silence them for the street so my ears don't get worse. I also have two 2 more pipes coming off those pipes into a Y connector/collector past the 4 speed Super T10 into a 3 inch single mandrel bent exhaust tubing with a reasonably quiet turbo muffler for the street. All three exits are used for racing and autocross. Quote Link to comment Share on other sites More sharing options...
Nealio240z Posted July 28, 2006 Author Share Posted July 28, 2006 Well thanks for all the help, Ill try it and tell you how it goes.... Quote Link to comment Share on other sites More sharing options...
Bowtiez Posted August 7, 2006 Share Posted August 7, 2006 Well thanks for all the help, Ill try it and tell you how it goes.... My motor started running rough since your first post during this hot spell I had put a 4-7 PSI electronic pump from Advance to replace a defective Holley Blue and the pressure was dropping from 5PSI to to 2.5 at part throttle. I bought a new Edelbrock gerator design (Essex) 6.5 PSI 120 gph and everything is running normal again. Pressure does not deviate regardless of throttle openning even with a deadhead system. I have the original 5/16" fuel line still in place that I could use as a return but am just too lazy. The Edelbrock is considerably quieter than the Holley and does not require a regulator, but its cost is $150. Let me know how you are doing. Quote Link to comment Share on other sites More sharing options...
LS2 V8 Miata Posted August 8, 2006 Share Posted August 8, 2006 Has anybody mentioned putting a piece heat sheild sleeve (Cool-it from Jegs or Summit) on the fuel line? Not even an original idea, Datsun did it as a Arizona "regional" option on the "new car" 72-74 240 and 260 Z fuel lines feeding our side draft carbs. If high temps is really the problem and not just some mechanical fuel starvation issue. It's also not a bad idea putting heat sheild sleeve on your underhood brake lines too. Quote Link to comment Share on other sites More sharing options...
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