posted
Rody, this is a really odd problem, my engine has been running fine till a week ago when it suddenly started running hot, I reset the needles same prob, pulled it apart clened it even replaced the washers arround the main and idle needle no fix (it seems to me that the LSN adjustment is not having its normal impact on the engine, not sure how this is possible), I am at a loss as to what to try next, it starts easily from cold is responsive its just that the temps keep climbing
Posts: 89 | From: jamaica | Registered: Sep 2004
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posted
Check all the fuel arrival to the engine. Take apart the main-needle and check it for dirt. Check the fuel-tank and see if it supplies sufficient fuel. Check the pressure line and if it is free.
posted
Rody, I've replaced all fuel lines and the fuel tank, removed and cleaned my main needle and my idle needle as well still same problems.
Posts: 89 | From: jamaica | Registered: Sep 2004
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posted
yep, I've tried trinity and Odonnel 20%, the trinity is what I broke it in with and it was running fine on that diet but when I started having probs I tried the Odonnel that my friend had - same issue. I dont know how to check the pressure from the pipe but I did try 2 different pipes (mine is the TM01) and i borrowed a 086 same probs, is there a specfic way to check the pressure ?
Posts: 89 | From: jamaica | Registered: Sep 2004
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posted
k, this am i changed the routing of the lines from the fuel tank to the carb using a much shorter path with a new piece of fuel line I also did the same with the pressure line from the pipe to the gas tank. I'll give it a try on the weekend to see how that works
Posts: 89 | From: jamaica | Registered: Sep 2004
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posted
Just to rule out some very worrying possibilities Rody, damaged piston/sleeve woudl'nt cause this or defective LSN right ?
Posts: 89 | From: jamaica | Registered: Sep 2004
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posted
hmm, as best I can I pulled it apart cleaned it up, sealed it, saw no signs of anything odd, it has good compression but the only think that worries me is that it seems to develop this problem after its warmed up. but its not spiraling out of control as would be expected with an air leak, it actually feels sometimes like its loosing power.
Posts: 89 | From: jamaica | Registered: Sep 2004
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posted
Then I guess there must be something with the carburetor setting, this is very hard to solve from here. Are you sure something is not binding in the car, it could be this also...
What happens if you open more the main needle when the engines starts to loose power?
posted
I can't really say, to be honest this weekend I'll have a look at all these things I have made some adjustments to my fuel line length hopefully that may pay dividends but I'll also look into the effect of opening the HSN when the motor starts to loose power
Posts: 89 | From: jamaica | Registered: Sep 2004
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posted
As you look through this topic you also notice that there are many things which can go wrong around the engine and make it malfunction. Sometimes it is a very small thing...
Anyway, good luck with your testing and hope you find the problem.
posted
Thanks Rody, I appreciate your assistance, I'm thinking that this is a block in the carb somewhere but just not sure where, I'm thinking of getting a can of compressed air and blowing out the ports, does this make sence ?
Posts: 89 | From: jamaica | Registered: Sep 2004
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posted
Rody, I reran the hoses and cleaned and reassembled the motor, and while I was testing I discovered that there were air bubbles coming from under the plug even tho I had tightened the plug, I replaced the plug and a new washer but had the same problems (it looks like the plate has been scratched and is no longer sealing properly) could this be the cause of my problems ?
Posts: 89 | From: jamaica | Registered: Sep 2004
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Depending on how much it is leaking it could change indeed something on the carburetor setting.
Anyway, to solve this, disassemble the combustion chamber, then flatten the part which is in contact with the washer with some sandpaper(600) on a flat underground to get the sealing perfect again.
posted
Hi Rody, havn't had a chance to run the mcar yet, work has been real hectic these last few weeks, and I had to do a diff rebuild as well. However yesterday I put the motor and the truck back together (I had done the polishing with the sandpaper, that got rid of the bubbles beautifullY) I wasn't ablt to actually drive the truck but I did start it and have it idle through an entires tank of fuel the temps were arround 200-210 troughout spiking at the end of the tank at 260, and it idled right through - no problems, so things look good!! I'll get a chance to run her this week but from that test it looks like my problem is fixed - thanks Rody!!
Posts: 89 | From: jamaica | Registered: Sep 2004
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posted
I think your LSN is set too lean, and before it was possibly on the edge of an OK tune, but atmospherics change, and if you were close to being too lean on the LSN setting, then it is very possible it's just a simple needle adjustment that's needed. If the 28 runs like other RB's, then the fact that it idles for a long time tells me right off that your LSN setting is WAY too lean. It is the LSN that is most responsible for keeping the temps down, and RB's like a Rich LSN setting. With a good race tune, most engines will begin to load up if left to idle through a complete pit stop. I set my LSN so the engine loads up pretty quickly, and you may need to raise the idle to keep it from flaming out, but once cleared out on the track, the bottom end will hit hard, and stay consistant, not fade after the engine comes up to temp, coupled with high temps, and numb needles, which is what you get with a LSN that's set too lean.
Posts: 994 | From: santa rosa CA | Registered: Apr 2004
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posted
Mike - that sounds like the issues I was having, but would'nt setting it back to factory fix that ? Or are you saying that at times you may have to set the lsn richer than factory ?
Posts: 89 | From: jamaica | Registered: Sep 2004
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posted
All carbs are slightly different, so the factory settings are only close, and sometimes not even that! Fire your motor up, if the low end is all snappy and spunky right off, you are too lean on the LSN. If it responds sluggishly, and slowly gets to where it runs OK, then you are too rich on the LSN. Run it, get it hot, bring it in, and note how long it takes to load up and die. It should not die immediately, that would mean you're too rich on the LSN, it should idle high for a scond or two, then drop to a nice low idle, and then begin to load up and die maybe 10 seconds or so later. If the engine idles well after it's warmed up, you are too lean on the LSN. Richen the LSN til it loads up after a short time. Don't worry, once cleared out the low end power will remain consistant. The temps will drop, and you'll probably have to lean the HSN a bit also. Once the LSN is set rich, I think your problems will go away. I think what you're experiencing is what's called a "Lean Bog", where there's not enough fuel in the case from the overly lean LSN setting, so when you open the throttle, it starves.
Posts: 994 | From: santa rosa CA | Registered: Apr 2004
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posted
Make sure your fuel is fresh and your filter is clean before adjusting. A dirty air filter will cause a rich setting on your motor and if you adjust the carb while it is dirty,then you will have a possible lean setting when the filter is clean.
Posts: 99 | Registered: May 2004
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posted
Hey Mike, I actually got rid of my overheating problems earlier after a rebuild and an exercise with some sandpaper
However I tried you tuning tips and my power is up and temps are down!!
This is very cool!! (no pun intended)
Mydixie - thanks for the advise just cleaned and reoiled my air cleaner (something I do tend to overlook)
Posts: 89 | From: jamaica | Registered: Sep 2004
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posted
Great! What you were describing sounded more like a tuning issue, I'm glad i could be of help.
Posts: 994 | From: santa rosa CA | Registered: Apr 2004
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