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| SU ruinning lean under load/rpm https://ausmini.com/forums/viewtopic.php?f=2&t=101071 |
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| Author: | Mick [ Tue Jul 27, 2021 8:23 pm ] |
| Post subject: | SU ruinning lean under load/rpm |
I've been out of the tuning mix for a little too long, and I need a little advice. I've been tuning a 998 with a 1.5" carb, rebuilt it replacing the jet and needle, float valve etc. I've replaced the needle back to stock (ABX) for an 1100, and centred the jet nicely. There's no cam, stock 998, nothing significant with the tune. Now I 've put it all back together and mounted it on the engine, but am finding a miss under acceleration from 3k which disappears if I pull the choke on. I tune the carb with a colortune at idle, hoping I've got it nice and tuned. I seem to get the correct response from lifting the piston just a little as well, but it just seems to be too lean through the range. Fuel flow from an SU electric pump seems fine too. It does have an anti-dive spring valve in the middle of the butterfly, can this be a drama when tuning as they get old? Can I have a few tips? I don't want to burn a valve out here. Thanks |
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| Author: | gtogreen1969 [ Wed Jul 28, 2021 1:42 am ] |
| Post subject: | Re: SU ruinning lean under load/rpm |
Try thicker dashpot oil |
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| Author: | drmini in aust [ Wed Jul 28, 2021 3:27 pm ] |
| Post subject: | Re: SU ruinning lean under load/rpm |
CP4 needle worked for me (with ramflo filter) |
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| Author: | Mick [ Wed Jul 28, 2021 11:53 pm ] |
| Post subject: | Re: SU ruinning lean under load/rpm |
Ok, will go back to thicker oil (I have autotrans fluid atm), but I'm confused as to why it would drift away from a standard needle. Does the RAMFLO affect the mixture behaviour much at all? |
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| Author: | drmini in aust [ Thu Jul 29, 2021 5:29 am ] |
| Post subject: | Re: SU ruinning lean under load/rpm |
This car came to me with a Ramflo already on it, I had some CP4 needles so I tried one. I doubt the HS4's usual big donut filter would be much more restrictive... |
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