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Old 01-23-2009, 04:14 AM   #1
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Default Hows the hot restart on big blocks?

Hey guys.
I'm wondering how I can improve my hot restarts on my 5.2cc. 25% nitro, OS R5 plug, NiCd glow heater, roto start, 2 needle carb.
I have the engine tuned very well, awesome top end, idles for ages, doesn't bog down, but I am really struggling to get it started when its hot. Basically its go have a quick smoke then try again. Its not vapour lock as I end up flooding the engine. I'm just missing that magic window when it first shuts off getting in their and firing it back up straight away again.
Prehaps the problem lies with how its shutting down? Usually the only time it shuts down is after a roll over, obviously air in the line that doesn't clear and makes it to the carb?
Rambling on a bit here...
1) How can I improve my hot restarts?
2) Any tips on how to keep air in the fuel line to a minimum after a roll over?

Thanks in advance for any suggestions.
Nathan
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Old 01-23-2009, 05:08 AM   #2
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Give it 1/4 turn more rich on the high speed needle. Shouldn't stall from being upside down for a bit. The carb gets to hot and the fuel won't travel thru the fuel line when you try and prime it, or when the compression tries to pull it thru.

1/4 turn is probably more than you need, but alot of times a drastic change is much easier to tell if it helps or not than just a little change. Good luck and happy motoring.

If the engine has alot of time on it, then it could be just worn out. When they lose compression they never like to fire up when warm. They don't like to idle and will only run lean also. If it's not that old then it probably just needs richened up.
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Old 01-23-2009, 06:11 AM   #3
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Originally Posted by jbrow1 View Post
Give it 1/4 turn more rich on the high speed needle. Shouldn't stall from being upside down for a bit. The carb gets to hot and the fuel won't travel thru the fuel line when you try and prime it, or when the compression tries to pull it thru.

1/4 turn is probably more than you need, but alot of times a drastic change is much easier to tell if it helps or not than just a little change. Good luck and happy motoring.

If the engine has alot of time on it, then it could be just worn out. When they lose compression they never like to fire up when warm. They don't like to idle and will only run lean also. If it's not that old then it probably just needs richened up.
I agree an engine that is on its last leg doesn't like to fire when its hot. It could also be a lean bottom end or an air leak.
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Old 01-23-2009, 07:17 AM   #4
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Originally Posted by HJTRBO View Post
2) Any tips on how to keep air in the fuel line to a minimum after a roll over?
I would 'prime' the engine. This means plugging the exhaust stinger (your thumb w/a rag or something) then just turning over the engine a few times. no glow plug starter, just turn it over with the exhaust plugged. What this will do is force more air flow thru the pressure line and fill the fuel feed line with fuel, thus lessening the amount or air in the line and the hard re-start.

Without knowing a TONNE more about what your settings and stuff are at, that would be my best suggestion.

db
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Old 01-23-2009, 08:36 PM   #5
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Give it 1/4 turn more rich on the high speed needle.

If it's not that old then it probably just needs richened up.

cheers
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