wondersparrow Posted May 4, 2009 Share Posted May 4, 2009 So I took my 240z battle tank to the race school. All I can say is that the s30 is one sweet as car. The AZC brake kit (6 piston front 4 piston rear 12.25" disks) were able to far outbreak some pretty serious cars (ie. a new GTR) The tilton dual master cylinder setup was bang on, perfect balance pretty much right out of the box. The car hauled pretty good, but ran into a few problems relating to the trip webers. First off, my idle was way out to lunch, had it tuned here, but the city the school was held was at a much higher elevation. It was more than simply turning screws could fix. Guess its time to order a bunch of jets. The second problem was that I boiled the fuel in the carbs. Probably due to all the idling waiting in line for the different exercises. So a small fire brought some added excitement to an already exciting day. Has anyone else run into this issue before? What did you do to fix it? Some of the things I would like to try out are - ceramic coat the headers, build a heatshield for the carbs, and have a really close look at my timing. I was running VP M109, so I may need more advance. All in all a great weekend, but now I have some homework Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 4, 2009 Share Posted May 4, 2009 Sounds like you don't have the insulators between the carbs and manifold. Quote Link to comment Share on other sites More sharing options...
wondersparrow Posted May 4, 2009 Author Share Posted May 4, 2009 I have the little plastic ones with o-rings. I really do think that all the heat was coming up from the exhaust header. That and it really didnt like idling. It would get quite hot in just a minute or two. Probably time for a better rad, maybe some electric fans. I may have been over fuelling the engine at idle (esp for that altitude). The engine was prepped by the previous owner. It has a full-out race cam of which I have no specs (but will investigate soon), flat top pistons, 10L nissan comp oil pan, and an extremely well ported head. I just put in the entire exhaust system, bought it used. It was only ever used in one race meet about 8 years ago, which I was at. The car won every race . Its 6-2 header with a custom collector to a 2.5" straight pipe. The jetting in the webers is quite large for a 2.4L and I found out this weekend that the prev owner never really got the carbs right. I have completely rebuilt/cleaned all of them, but I will likely want to tone down the jets later. I post what I am using tomorrow after a good night sleep. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 4, 2009 Share Posted May 4, 2009 Are you running the mechanical fuel pump or the stock fuel rail? Those are two ways to put lots of heat in the fuel before it gets to the carbs. FWIW, I've run my Mikunis with no heat shield in 105+ F degree weather and never had any fuel boiling issues, but I did get rid of the mechanical pump and fuel rail. Quote Link to comment Share on other sites More sharing options...
cary Posted May 4, 2009 Share Posted May 4, 2009 Sounds like you don't have the insulators between the carbs and manifold. Sound like it.. Quote Link to comment Share on other sites More sharing options...
josh817 Posted May 4, 2009 Share Posted May 4, 2009 If nothing has been done to the headers like a wrap or ceramic coat then thats a biggy too. I have my headers coated with a silver ceramic which polishes out. Drops the temperature way way down and is also a god rust prevention. Just got a second set done so if you need a 6-1 coated header with a 3 bolt flange welded on then you could buy mine I do suppose. As Dad always put it, heat shields are like condoms. The problem is still there but you're just preventing it from causing trouble. Ceramic coat is like abstinence. haha Quote Link to comment Share on other sites More sharing options...
wondersparrow Posted May 4, 2009 Author Share Posted May 4, 2009 well, I think both options are going to be put in place. My plan for a heat shield was to cover both sides of a piece of aluminum with sheets of manifold gasket material and bend that into a nice heat shield. That would both insulate me better from the intake manifold and the heat below. For reference, my carbs are setup as follows. 45dcoe carbs, 36 chokes, 55F9 idle jets, 45 accel jets, 180 air corrector, F2 emulsion tubes, and 140 main jets. I live in Edmonton and the race was in Calgary, I belive that the elevations are 2373' and 3557' respectively. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 4, 2009 Share Posted May 4, 2009 well, I think both options are going to be put in place. My plan for a heat shield was to cover both sides of a piece of aluminum with sheets of manifold gasket material and bend that into a nice heat shield. That would both insulate me better from the intake manifold and the heat below. Cover it with a header blanket if you want to do that. I had a friend run two sheets of aluminum with a header blanket sandwiched in between. Quote Link to comment Share on other sites More sharing options...
wondersparrow Posted May 4, 2009 Author Share Posted May 4, 2009 hmm, excellent idea as well. The blanket probably wouldnt make a good sealing surface between the carbs and the intake manifold though, but a combination of the two would work out well. To answer some of the questions above... Electric fuel pump coming off a fuel cell, thru a race filter and regulator, to a little manifold. Equal length rubber fuel lines from the manifold to each carb..... The headers and exhaust are all bare, no thermal insulation of any kind. I was going to take care of that after the school anyways, didnt think it would be an issue if i wasn't running it that hard. Quote Link to comment Share on other sites More sharing options...
josh817 Posted May 4, 2009 Share Posted May 4, 2009 Aluminum is a conductor, works but then again once it gets hot, it doesn't. Already went through this argument between Dad and I and some dudes who were obsessed about saving weight. We have a guy laser cut stainless heat shields for our carbs. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 4, 2009 Share Posted May 4, 2009 Aluminum is a conductor, works but then again once it gets hot, it doesn't. Already went through this argument between Dad and I and some dudes who were obsessed about saving weight. We have a guy laser cut stainless heat shields for our carbs. It's a matter of degrees (pun intended). An aluminum heat shield works better than none, and one with a header blanket works better than without. Stainless is a better choice for a heat shield, no doubt. If you have the money, go stainless. Quote Link to comment Share on other sites More sharing options...
josh817 Posted May 4, 2009 Share Posted May 4, 2009 For some reason I can see a heat blanket working really well as in like you're able to touch the part that faces the carb. Maybe I'm going insano. Quote Link to comment Share on other sites More sharing options...
wondersparrow Posted May 5, 2009 Author Share Posted May 5, 2009 thats kinda what my goal is going to be. I want those carbs to be cool before getting back on the track. Quote Link to comment Share on other sites More sharing options...
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