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Rolling Road Test


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#31 gaspen

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Posted 08 October 2021 - 06:29 PM

Great news - sounds like it's chalk and cheese ?

 

The amount of advance sounds about right. I should have mentioned in the numbers I gave above, those are the originals from the days of leaded petrol. Mini Spares apparently have them tweaked a little to better suit unleaded fuels, so there'll possibly be a degree or 2 difference here and there in the curve from those numbers. The distributors I've tested in their range have been for 1275 engines and they track bang on to the original curves, others might have some variation as mentioned.

Proof of the pudding as the say, is in the eating. If the engine does everything it should - starts on the button, drives without pinking, temps stay in the right range, cruises smooth, accelerates as you would expect - then you can be reasonably sure, at worst, that it's close to the mark and likely to get any better would involve a rolling road session and the dissy tweaked from that.

 

In regards to your dwell angle I've never looked in to that nor measured that for these with the Electronic modules - not much you can do about it anyway, however, as they switch 'clean' they will need less. When I say switch 'clean', if you were to look at how points switched on an oscilloscope, you'd notice as they open and close, the current doesn't snap from off to on and on to off, but there's some 'fuzz' or 'noise' at these occurrences, where as the electronic module does snap open and closed clean. By doing so, it needs less dwell and even with the same coil, you'd find that when running from the electronic module, it'll have a higher output voltage as a result of this clean switching.

 

As you say !

 

Regarding the advance : after so much reading I should have learnt that modern fuels allow more advance  :shy:

 

Learning from our own experiences is priceless !  :lol:

 

Thank you again, Moke !



#32 Ethel

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Posted 09 October 2021 - 11:32 AM

I wouldn't say "allow more", more like require more - but they will insist on kids growing up with a full compliment of brain cells nowadays.



#33 Spider

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Posted 09 October 2021 - 07:40 PM

Learning from our own experiences is priceless !  :lol:

 

I've always found I learn at least 10 times more from 'failures' or 'issues' than if it all goes smooth. When it does go smooth, you don't know what the limits are and why.

A good mate of mine always said there's no such thing as a mistake, we only have learning experiences.



#34 gaspen

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Posted 20 November 2021 - 07:03 AM

New question here  :proud:

 

I am thinking to put the car to a rolling road test. There is a "one-person" company in my area. 

 

For a price of one test I can get the power/torque curve for the whole RPM range of the actual setup.

 

What I would like to know if the ABX needle in my simple HS4 fits to the engine.

 

Should I ask the person to measure the CO also for the full range to determine which needle is appropriate ?



#35 sonscar

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Posted 20 November 2021 - 11:45 AM

Whilst the co is important it is best to tune the motor to what level is needed for safe efficient operation rather than a fixed figure.Others may well disagree.Unless there are specific amounts dictated by laws I find this the most rewarding way of doing it.Just my ancient view,Steve..

#36 Spider

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Posted 20 November 2021 - 06:46 PM

I'd suggest getting in touch with them and have a chat. Most rolling roads are used to make adjustments to the fuel and ignition system to best optimise the way the engine runs. They will likely be able to tune your engine, but they may not have a variety or any needles for an SU, so it maybe worth fronting up with a few profiles and also a thicker (leaner) one that can be re-profiled on the day. I don't like the latter as it's seldom done with the accuracy needed and it's a mission after to plot the needle profile so you know what's in it and hopefully find a 'proper' SU profile to match. If your carb has a Biased type of needle fitted, these do wear and need routine replacements.

The other thing that's usually done on a rolling road is a power run. They should do one on the car first, before doing anything else, so they have a base line to work from and also see just how it's performing, while doing these power runs they will normally measure the exhaust gases and some will have tuned headsets to listen to the engine for 'knock' if the ignition system is too advanced.

 






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