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| 2280 carb question https://slantsix.org/forum/viewtopic.php?t=54674 |
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| Author: | valiant effort [ Fri Feb 21, 2014 7:28 am ] |
| Post subject: | 2280 carb question |
I have a 1964 valiant which I upgraded to super six, It has a rebuilt 170 with a mild cam and recurved distributor from DI. Also has been upgraded to HEI. I currently have a new Holley 2280, not rebuilt, and I am trying to fine tune it. My question involves the fuel mixture screws. It seems that as I adjust them out there comes a point when there is no longer any change in idle. The reason I ask is that I have to adjust them out at least 4 turns to have a decent idle speed. Anything less than that it begins to shut down. As I adjust them out and I get to that point where there appears to be no change is where I finally get a decent idle. I wish I could go a bit further but as I said no change after a certain point. Btw, the distributor is set at 14 degrees advance. Any comments are welcome...thanks Mark..no vacuum issues btw. |
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| Author: | Reed [ Fri Feb 21, 2014 8:45 am ] |
| Post subject: | |
On later carbs there is an idle mixture limiter that will limit how rich the idle mixture screws will allow the air/fuel mix to get. If all you are trying to do is increase idle RPM, have you tried turning the idle speed screw in instead of turning the idle mixture screws out? |
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| Author: | valiant effort [ Fri Feb 21, 2014 4:26 pm ] |
| Post subject: | 2280 |
Thanks Reed. Actually I am just trying to get it to idle a bit slower but still not cut out. I may try to advance the timing just a bit more and see if that helps but I am already at 14 degrees advanced. I recall Charlie mentioning that these later model carbs do run a bit too lean so I am guessing that is a lot of the issue. Also the idle does seem to get slower after a nice long drive to the point where it almost cuts out. I will just keep trying different things until I am happy. Thanks again for the response..Mark |
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| Author: | Josh P [ Fri Feb 21, 2014 8:03 pm ] |
| Post subject: | |
Shot in the dark, but its been mentioned that the BBD is about the biggest carb you'd want to use on a stock-to-mild 225 (which would mean it should be too much for a 170). Obviously, you don't have a BBD but I think the 2280 is roughly the same size. So is this a possible too-much-carb situation? I would guess if your 170 is roughly stock with a mild cam you might need to back down to a smaller carb. I'm sure others, with a lot more experience, will chime in. In the meantime could you list some specs about your rebuild? DCR, cam lift/overlap, etc it should help get a better idea of how much carb you should be running. To the gurus, anyone run a supersix 170 with success? |
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| Author: | valiant effort [ Sat Feb 22, 2014 4:28 pm ] |
| Post subject: | 2280 |
I will dig out the build sheet. I should have mentioned that Charlie S did the rebuild and is familiar with the carb I chose. Nonetheless its something to look into. Thanks |
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| Author: | Reed [ Sat Feb 22, 2014 4:47 pm ] |
| Post subject: | |
How slow are you trying to get it to idle? |
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| Author: | ValiantBoyWonder [ Sat Feb 22, 2014 8:08 pm ] |
| Post subject: | |
Vacuum leaks? Pcv stuck open? Float level? Crud in the idle circuit? |
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| Author: | valiant effort [ Mon Feb 24, 2014 4:35 pm ] |
| Post subject: | 2280 |
Since most of everything I am dealing with is brand new like PCV, Carb, Engine, etc etc I would doubt it was a stuck PCV or crud in the idle mixture. New gas tank too by the way. The float level is certainly a possibility and I have not looked into that. I will do a search to see how that adjustment is best done. Most likely trial and error. Thanks for the responses..Mark |
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| Author: | matv91 [ Mon Feb 24, 2014 6:16 pm ] |
| Post subject: | |
Reed is right http://www.slantsix.org/articles/choke- ... -info2.jpg Limter is small brass piece in the idle down channel just above mixture screw. Needs to be enlarged or removed. |
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| Author: | Reed [ Mon Feb 24, 2014 6:42 pm ] |
| Post subject: | |
How fast is it idling now, and how fast are you trying to get it to idle? You may need to loosen the clamp on the accelerator cable to get the throttle to close further. |
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| Author: | valiant effort [ Mon Feb 24, 2014 7:29 pm ] |
| Post subject: | 2280 |
It is going along about 900 rpm right now.I would like to get it down to about 700 but when I get to that number the engine just cuts out. I might add also that's when it gets warm it almost will not idle at all. |
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| Author: | Reed [ Mon Feb 24, 2014 8:03 pm ] |
| Post subject: | |
OK- sounds like possibly a vacuum leak or most likely a too-lean idle circuit. However, there is no reason even a pollution controlled 2280 wouldn't be able to run a mostly stock 225. |
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| Author: | ValiantBoyWonder [ Mon Feb 24, 2014 8:20 pm ] |
| Post subject: | |
What jets are in it now? |
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| Author: | valiant effort [ Tue Feb 25, 2014 4:31 pm ] |
| Post subject: | 2280 |
Thanks for the responses. I am going through it one more time for vacuum leakes but I really don't think that's the issue. As Reed said its most likely the idle circuit. I had a spare 2280 so I took it apart today to see what the idle limiter was. I think the one I took apart must be an older 2280 because it did not seem to have the idle limiter shown in the diagram or else I just don't know what I am looking at. I will keep at it. I did notice that in the old one a lot of the screws were not terribly tight so I will check the ones on my regular one before I go any further. If I was to adjust the float level, given my current problem, would I adjust it to allow more fuel or less. Thanks for the replies. Mark...p.s. I do not know the jet sizes. |
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