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Post by 998automan on Jun 16, 2015 18:04:54 GMT
Hi, I need to re-set the mixture on my HS4 following re-build. Years ago I had a mini with a piston lifting pin on the carb that enabled you to set mixture quite easily, my question is is it safe/possible to stick your finger in the throat of the carb and lift up the piston manually whilst the engine is running? Or if not any other ideas/tips that don`t involve a trip to the garage!
Cheers Mike.
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Post by kalkat on Jun 16, 2015 18:43:19 GMT
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Post by Stu on Jun 18, 2015 22:32:53 GMT
Buy yourself a Gunsons colour tune Mike. Itll get your mixture close enough for idle and normal driving. You can then fine tune using plug colour / condition.
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Post by notamini on Jun 23, 2015 1:06:18 GMT
Are you sure you haven't got the pin? I should be right on the inside edge next to the float bowl if you have the bowl on the right of the car. I always start with 9 flats of the nut from tight.That is usually within 2 flats, sometimes within 1/2 flat or less.
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Post by 998automan on Jun 24, 2015 19:02:09 GMT
Thanks, yeah sadly no pin. Have found someone with a gas analyser who set it at 4% co2. Haynes manual shows 3.5-4.5% until 1985 when it dropped to 2.5! I assume that this was just an effort to get emissions down as the carbs are the same as the earlier ones as far as I can tell, what do you guys feel is right? Also seeking opinions on air filters, thinking of switching to a K&N cone, any idea of correct needle required for this filter on a HS4? Currently running K&N element in standard housing but noticed how much better it ran without a filter and how much the engine struggled when filter was replaced after tuning.
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Post by Stu on Jun 24, 2015 19:32:42 GMT
A lot of folks think installing a K&N filter will improve performance on a stock engine / carb. The standard paper filter is more than adequate to allow the engine to perform in my opinion. David Vizard did bench flow tests years ago on the paper filter and K&N and found very little improvement. The engine will always run better without a filter, but won't last too long of course. I would agree they look good in the engine bay, but for improving performance I'm not convinced. I'd rather spend the same money on a rolling road session to sqeeze out a few more bhp through tuning. Just my opinion though.  |
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Post by hbroodryk on Jun 24, 2015 20:16:45 GMT
Hi
i don't want to start anything here, but according to the info on p45 and 46 of the Yellow Bible (New Edition published 1989) a K&N will almost always flow more air than a paper element filter. The difference does vary quite a lot depending on the quality and design of the paper element by the looks of it, but will always rather use a K&N rather than no filter at all.
You will have to spend some time and energy on getting the correct needle if you DO change to a K&N and I absolutely agree with Stu about investing in some RR time to get the best out of what you already have rather than just changing things and hoping for the best.
BTW, I am not some sort of anorak, I just happen to be reading the Vizard book at the moment...
Regards
Hannes
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Post by Stu on Jun 24, 2015 21:57:16 GMT
Yes a good point Hannes. I should have checked what I'd written. What I really mean is that you could install the best, highest flowing filter money can buy, but if you fit it to a standard head with no flow modification to the ports, the benefit would be marginal at best, if even noticable in performance.
If, however, you combined a performance filter with a staged head, performance manifold and needle to suit, and set it all up on a rolling road, there would clearly be significant increase in performance and the benefits of the filter would be integral to the set up.
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Post by hbroodryk on Jun 25, 2015 13:38:38 GMT
Ah, good; I haven't inadvertently caused anybody any offense (my style of writing comes across as abrupt quite often, so I am trying to be cautious of that. English is not my first language).
I'm all for "better" parts as long as they are used properly. Any performance parts that are just added without some level of (for lack of a better term) recalibration of the whole engine will not be of any benefit. If the original part is restrictive/rubbish to start off with you may well get lucky and notice an immediate improvement. If the car currently runs noticeably better without any air filter element I would certainly be tempted to try a K&N or other free-flowing set-up to see what happens...
Regards
Hannes
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Post by 998automan on Jun 26, 2015 8:17:21 GMT
Thanks all, good advice I am sure. I think the time has come to invest in a decent manifold/exhaust/filter find a rolling road and start experimenting! Anyone know of a good one in the South West?
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