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Old 10-10-2012, 01:03 AM   #1
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Default os 21xz-r speed on a 1/8 gt car

I switched back to the os 21 speed and i must say you guys were right! there's really no need for anything over a 21 on this car. it hauls just as good as the roma but with more top end and the low end is more linear. My question is, should i use the os 2060 off road header with the 2080 pipe? The 2080 is the recommended pipe set for the engine but the on road header will not work. I have a novarossi 41021 header that im using with the 9886 pipe but would feel better if i could use the 2080 pipe. So is the 41021 ok or should i buy the 2060 header?? Thanks in advance.
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Old 10-10-2012, 01:14 AM   #2
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I also noticed that after i do a couple high speed pulls, the idle drops down real low and the engine shuts off. When i try to restart it, it is very hard. I can see the fuel in the line and it looks like as soon as it gets to the carb, it pushes back? I've never seen anything like this. Could it be not enough pressure in the pipe? at first i figured the fuel was boiling from the carb being hot and that could be the case but i even richened it up on the hsn and low just a tad and temps are 220. Seems like it shouldnt do that at that low of a temperature. Thats another reason i want to change the pipe because when i used to run this engine in my other car temps would stay at 215-220 all day long and i could cut it off and crank it right back up. It just acts like something is pushing the fuel back from the carb once its warmed up. any ideas?
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Old 10-10-2012, 03:08 AM   #3
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Looks like the engine is at the end of life. When the engine is cooled down it will start again?
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Old 10-10-2012, 03:14 AM   #4
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yes. it starts up no problem when it cools and fuel enters the carb nipple.
could it be vapor lock? and how to prevent it?
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Old 10-10-2012, 04:53 AM   #5
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Looks like to low on compression when warm.
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Old 10-10-2012, 06:16 AM   #6
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Looks like to low on compression when warm.
So what's causing the fuel to be rejected at the carb? I hope it's not gone this has been a great engine. I changed all fuel lines and cleaned fuel filter and replaced exhaust gaskets. Will test again today.
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Old 10-10-2012, 10:19 AM   #7
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So what's causing the fuel to be rejected at the carb? I hope it's not gone this has been a great engine. I changed all fuel lines and cleaned fuel filter and replaced exhaust gaskets. Will test again today.
Had the same problem changed fuel line and removed silver polish from the pressure fitting blocking the nipple. ( Don't ask I like my pipe shiny) I would check all fittings including tank, pipe and blow out tank make sure its flowing. I had the same engine same car same experience.
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Old 10-10-2012, 10:22 AM   #8
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So what's causing the fuel to be rejected at the carb? I hope it's not gone this has been a great engine. I changed all fuel lines and cleaned fuel filter and replaced exhaust gaskets. Will test again today.
Is the motor spinning the correct direction. When looking at flywheel should spin counter clockwise
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Old 10-10-2012, 09:26 PM   #9
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Ok, so after many curse words and tired legs from walking to get it once it cut off, I found that i was 1/2 turn too lean on hsn. Factory setting is 3 turns out but i ended up about 3 1/2 to 3 5/8 turns out from fully closed. I remember with this engine since new turning the hsn in and backing it out several times, the hsn would go further down each time which in turn made 3 turns out not in the same position. Actually, it goes 1/2 turn in further than when i first broke it in. I got tied up focusing on other potential problems and forgot all about that. i guess the rubber seal on the hsn has "broken in" and allows the needle to go further to the seat. Also, i never ever applied pressure when turning it in to fully seat. Now, it cranks on the first bump and idles all day long. High end has great response, no more low end bog, temps 215-220 again. Settings are 3 1/2 out on hsn from "my" fully seated, lsn almost a full turn in from .5mm out from flush and idle around .6-.8mm gap. Running 9mm restrictor. It screams now and no more boiling fuel after 2 or 3 high speed passes. I can pinch the fuel line and shut it off and crank it directly back up with one bump on the box. Also, in my troubleshooting, i changed and lengthened the pressure line, changed and lengthened fuel line, cleaned fuel filter, cleaned tank, replaced all exhaust gaskets, added more tension on slide return spring, flushed and cleaned pipe and header, and went over all linkages.
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