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| Idling high https://www.slantsix.org/forum/viewtopic.php?t=43336 |
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| Author: | Ross [ Fri Jan 21, 2011 8:16 pm ] |
| Post subject: | Idling high |
Well after I installed my tach ive been able to see what my engine idles at. Ive adjusted the timing to 10 degrees btdc. The normal timing is to be set at 12 degrees btdc. Since i have a manual tranny my idle speed is supposed to be 600 rpms. My idle speed doesnt go below 800 rpms. On a warm idle. Typically its about 900. The high idle is i guess supposed to be in the 1800+ range? Im not sure. Some times it idles at 1100-1200 rpms while warming up. some times it goes to 1800 or so and itll keep going up on its own till i hit the throttle to bring it down to normal idle. I had the carb proffesionally adjusted so i could pass deq. Could that be it? I did some tinkering with the timing and the lowest i could get the idle was about 650 rpms at 0 degrees. about 750 at 5 degrees btdc. but being that low it was gutless as hell. (no i did not drive it like this, just gave it some throttle and it fell flat on its face). Im just wondering why it idles so high, and if i can get it idle lower. Any help and suggestions will be appreciated. thanks |
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| Author: | 4speed [ Fri Jan 21, 2011 8:26 pm ] |
| Post subject: | |
At hot idle is your throttle cable slack? It must be slack to let the carb throttle valve fully close. Also with you high idle you can not set timing because as the speed goes up you ignition timing gets more advance (this is the mechanical advance working like it should). 10/12 degrees before can only be at the correct idle speed. Check your throttle cable. |
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| Author: | Ross [ Fri Jan 21, 2011 8:37 pm ] |
| Post subject: | |
ok ill check the cable. I only played with the timing when it was fully warm and at normal idle. |
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| Author: | 4speed [ Fri Jan 21, 2011 8:46 pm ] |
| Post subject: | |
Remember as you lower the idle speed you need to up the timing. |
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| Author: | Ross [ Fri Jan 21, 2011 9:00 pm ] |
| Post subject: | |
how would i lower the timing? adjusting the carb? before i had the carb adjusted, it was running very rich and the timing was about 20 degrees btdc. |
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| Author: | ceej [ Fri Jan 21, 2011 9:10 pm ] |
| Post subject: | |
It's real tough to fix something like this remotely. Definitely check to see that you have some slack in the throttle cable, check for any vacuum leaks, and look for gotchas like carb gaskets or anything that could hang up the throttle plate moving back to a full closed position. You should be able to idle it down with 12° of advance to the point the engine dies. Perhaps you can hook up with somebody that's savy that's close to Portland. If your up for a drive, your always welcome to cruise down here. It's a few miles, but I'm sure we could figure things out. There's quite a contingent in the Salem area, then you have Fopar and I down in the southern Willamette valley. CJ |
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| Author: | 4speed [ Fri Jan 21, 2011 9:16 pm ] |
| Post subject: | |
What I am saying is as the engine gets closer to the speed it need to be your timing will retard as it should. You will just need to re-set the timing once you get the idle speed right. |
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| Author: | Ross [ Fri Jan 21, 2011 9:32 pm ] |
| Post subject: | |
thanks ceej. ill look at that stuff in the morning. i get what youre saying 4 speed. ive been real busy lately with work and fixing things on it that have decided to go out. itll be nice to have a day to work on it and check things out. |
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| Author: | Fopar [ Fri Jan 21, 2011 9:41 pm ] |
| Post subject: | |
As you change the timing have you reset the idle speed screw? That is the one that stops the throttle, when you change the timing you also will increase or decrease the idle (retarding usually slows the idle advancing will increase the idle) Richard |
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| Author: | ceej [ Fri Jan 21, 2011 9:46 pm ] |
| Post subject: | |
Check you pm's. CJ |
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| Author: | wjajr [ Sat Jan 22, 2011 4:35 pm ] |
| Post subject: | |
Check to see if the mechanical advance weights move freely in the distributor. |
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| Author: | Ross [ Sun Jan 23, 2011 9:19 am ] |
| Post subject: | |
I didn't check the weight in the dist. Yet. But I did tinker with the carb idle screw and timing. I got it down to about 700-750rpms last night. I do have lean burn. Would that make a difference? |
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| Author: | DusterIdiot [ Sun Jan 23, 2011 9:25 am ] |
| Post subject: | Yep... |
Quote: I do have lean burn. Would that make a difference?
Yep, your distributor has no weights or springs...and not much to adjust there other than "initial"...If the carb is for the lean burn it won't have much tuneability for idle like the 70's carbs.-D.Idiot |
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| Author: | Ross [ Sun Jan 23, 2011 11:32 am ] |
| Post subject: | |
Ok thanks d idiot. Now I won't be tearing my ditributor apart wondering where the weights are. |
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| Author: | wjajr [ Sun Jan 23, 2011 12:06 pm ] |
| Post subject: | |
Sorry did not realize you had lean burn. Another place to look at: Check any connections involving lean burn wiring for resistance creating corrosion. This may or may not be a voltage problem for the brain communicating with its various sensors, from resistance built up from corrosion. |
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