G'day Everyone,

I'm hoping to get some opinions as to what is causing the flatspots that I am suffering from at the moment. I have just installed a HS4 carb in place of my old HS2, running a stub stack / sock arrangement and a straight through exhaust system. I am suffering from flatspots on acceleration low in the rev range, however full throttle acceleration is quite good (noticeably faster than my HS2). From what I can tell the car is leaning out momentarily, which leads me to think that either the oil in the dashpot is too thin or maybe a weak spring. I was initially running 3in1 in the dashpot, which I used in the HS2 quite successfully, but changing to 20w50 didn't fix it. And I have tried various different spring arrangements and that doesn't make much difference either.
Does anybody have any ideas?

Cheers,
Anto.

I'm not much help here anton... only thought is perhaps weights/vac advance in the dizzy... but if the carbs the only thing you've played with, it must be that.... I was always told to use 10 weight/grade oil in dashpots... eg: sewing machine oit... ATF (auto trans fluid or power steering fluid- same stuff).... I once had a set of twin SU's that I couldnt get right... found thay had diffrent colored springs (diff color, diff spring rate/tension) replaced them, and a few bits, and as they say.. problem solvered.


As for a single carb... no Idea.. Dr Mini Aus will know for sure....

-Cam

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IS NOW BACK ONLINE AFTER SOMETIME..... SORRY TO ALL, FOR NOT REPLYING TO PM'S!!

The sewing oil thing comes out of colder places such as Europe where a thinner oil is required. In Australia where the temperatures are never really low (lets face it even if you live in the rain capital - Melbourne) you should just be using normal light motor oil (20/50).

Ahh ok, my bad...sorry lads.... and sorry ANTo... for calling u Anton.. lol didnt notice

-Cam

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IS NOW BACK ONLINE AFTER SOMETIME..... SORRY TO ALL, FOR NOT REPLYING TO PM'S!!

Sounds like your needle is too lean in the midrange.. maybe..

I've got the same prob in the 1132 Clubbie, I just make it richer to disguise it..

When I fit the Dellorto 40DHLA I won't have the problem!

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Well I use a stright 30 grade oil in mine and yes it sound like it is to lean.

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I've Got One
You've Got One
We've All Got One
What Is It



A Bloody Mini

1970 Mini K, 1380cc, 1.75 HIF SU, 30 70 Cam, 2" Zorts
1969 Mini K, Stock Standard and Orginal. (Slow as Hell)

hey guys, I just had the 80 000 k service done on my clubby today. (27 years late, i'm lazy). I also had a flat spot in my carby (very similar condition). but not knowing a thing about em, wasnt overly worried.

The mechanic replaced the points and condensor for me, and tuned the carb. I was amazed at how much better it was after having a professional look at it. Now a 1.25 on a 1275 is too small, I know, but down low, it doesnt miss a beat anymore. He also had a look at the twins i have, and seems to think that they'll be fine to bolt on (BIG GRIN).

Anyway, this might not be much help, but I just thought i'd add it, since I had the same problem.

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"He's always been a dickhead, He always is a dickhead, He will always be a dickhead. So stop complaining when he acts like one."

Okay guys I believe I have found the problem, and you can laugh at me all you want for it, one of my less brainy moves
There was a slight vacuum leak where the carb attaches to the manifold. I didn't buy enough gaskets by accident so I thought maybe I could stoop low enough to use gasket goo, instead of making the trip down to buy another one. I must have been otherwise occupied when I put the goo on coz I used the wrong stuff (gasket assister not gasket maker) coz I couldn't find the gasket maker. Didn't think much of it at the time but of course it ain't gonna seal! When I was taking the carb off I realised immediately my stupid mistake and punched myself....
Also the throttle spindle is a bit worn so I'll replace that also (possibly explains crackling exhaust on deceleration).
So needles didn't fix the problem, although I could probably has concealed the problem with a rich midrange needle but that wouldn't have fixed it as such.

Cheers,
Anto.