11 replies to this topic

[maxmaniac]

Hello guys, I hope your knowledge can help me a bit ;)

 

First I'l try to describe how my car was before the modifications I've made in the last few weeks.

 

This guy is a bit of a mutt: it began as an austin mini 1000 from 1970 with a single hs2.

In the 90's the engine gave up and the way to rebuilt it was by using parts from a mini clubman (don't know the year...) and became a 1100 during that process.

To my knowledge, all parts are original except the engine itself.

So I had this:

- 1100cc engine

- hs2 carb with AN needle and red spring (I guess)

- standard exhaust (single box)

 

during the past couple of weeks I fitted a

- cooper freeflow manifold and a 1,75'' twinbox (all maniflow)

- a set of twin hs2's with EB's and blue springs (can't really tell the color but it is weaker than the one on the single hs2, so...)

 

The oil used on both carburettor setups is the same (power steering oil - don't really know the grade but it's heavier than standard su oil and lighter than engine oil)

The twins were all rebuilt including jets, butterflies, fuel bowl gaskets and valves, etc.
Using the standard choke setup (turning the jet nut 12 flats down), the engine fired right away and seemed fairly balanced.

Anyway, I proceeded to check the mixture on both carbs using a Gunsons Colortune (on cilinders 1 and 4) and afterwards balanced the carbs using a Gunsons Carb Balancer.

 

With no load, the engine works fine, rpm's rise nicely, etc. But when driving, there's a flatspot when the engine starts to pick up speed. Pretty noticeable when in 2nd gear, with the car almost stopped if i depress the acelerator slowly, the engine just bogs down; if I floor the accelerator, the engine rises and there is no problem.

Has I had also a pair of M needles, I thought I should give them a try and the problem got less severe. It still does it but now it's easier to drive in low gears.

With EB's or M's, in higher rpms there are no problems at all... This guy happily reaches 80 km/h in 3rd gear and 120 km/h in 4th with ease.

 

I also thought it could be the ignition timing, but as this car is a bit unique, I don't really know what the timing should be; anyway, with the engine running I turned the dizzy clockwise to find the maximum rpm and then turned a small bit counter-clockwise (so to make 250rpm less than maximum as I read here) and then proceeded to ajust mixture, balance carbs, etc all over again.

Is there a standard way to setup the ignition without just using the stated degree values on haynes manual or something?

 

In any case, I shot a small film using my cellphone while using the M's --> 

Both accelerations are on 4th gear:

- on the first one there isn't any obvious problem

- on the second one... Well, I guess you'll be able to hear it almost die before it starts to rise.

 

If you can give any opinions, I would be very grateful.

Thank you everyone!

[carbon]

Sounds like the engine may be running weak. The M needle will give a richer mixture than EB needle.

 

If you want to try richening up the mixture you have a couple of options. One is to fit red springs, second is to find a needle bit richer still than M but whatever you do would suggest you take it to rolling road to get mixture properly adjusted.

 

What air filters do you have fitted?

[maxmaniac]

Thanks for your reply!

I'm using cone filters I bought as being K&N ones, but they seem to be a knock off (probably minisport ones) as they don't have "K&N" stamped anywhere.

In any case, I tried driving it a bit without filters and the result was virtually the same.

 

Anyway, I have a small update:

Today I thought I should try a different kind of oil on the carbs and, guess what, using 15w50 (which was the one I had...) the flat spot disappeared!

It is almost flawless, but sometimes it still happens but I didn't figure out when it still happens; probably it can be sorted out with small tweaks on the ignition timing.

Anyway, I guess I will also try red springs just to see what difference they bring.

 

I wouldn't mind trying a rolling road but I don't really know any place near my location. I believe it's not something very common in Portugal, sadly...

[carbon]

Good to hear you have managed to get this sorted, I should have suggested trying 20W50 before any further changes to springs or needles.

 

Would recommend sticking with the M needles for time being, these were used on 1100 MG Midget as a richer needle option.

[maxmaniac]

In any case, your suggestions were also quite relevant.
I wasn't sure about the blue springs, but since I have none other to try, the oil was the easiest step to take.

 

But i'm still willing to try changing springs just to see the differences.
Regarding needles, I chose the M ones because although they're richer, the idle profile is the same as on EB.
Perhaps the EB's are more MOT friendly ;)

[carbon]

Sounds like your blue springs may be pretty close, I would suggest as next step trying the 20W50 instead of the 15W50, much quicker than changing springs.

 

If you do try changing from blue to red springs you will find that the idle mixture richens up and you will need to raise the jet heights quite a bit to get the mixture correct again.

 

If your MOT checks are on %CO at idle then it really does not matter too much if you have EB or M needles fitted, as long as the idle mixture is set correct. I would be wary of running the EBs, as these are a weak needle and the effect of the freeflow inlet filters and exhaust will be to further weaken the mixture. Better sticking with M needles. If M is too rich then GY or GX are between EB and M.

[maxmaniac]

I'll try the oil first, then!

 

After reading Vizard's "bible", I also thought the EB's were going to be too lean, that's why I ordered the M's (also because that's the ones he recommends for twin hs2 with 1100 with ported head).

Thanks for the other suggestions regarding the needles as I am no expert on this particular subject!

 

Regarding the MOT, I know that CO on diesels is checked at idle and 3000rpm, for gasoline I'm not really sure.

 

And regarding ignition timing, is there a particular way of setting it up without using pre-set values?
I read the haynes values, but with these modifications I'm not really sure where the advance should be. Vizard also doesn't discuss much on this subject, I'm a bit at loss.

[gazza82]

Regarding the MOT, I know that CO on diesels is checked at idle and 3000rpm, for gasoline I'm not really sure.

 

Think you will find that is just a smoke test on the diesels ... and they rev them to the red line ...

 

For petrol/gas, slow and fast idles to compare. Normally 2500-3000 rpm for fast.

[Dusky]

Have you a good dizzy for the 1100? Or still the 998 dizzy?
I had the same problems, atf oil in the carb solved a lot.

Edited by Dusky, 19 December 2014 - 11:31 AM.

[maxmaniac]

Hi all, thanks for your replies!

 

gazza82, I'm not really sure how they test petrol cars, but for diesels they sure rev them up but I was thinking they only done so until 3000/3500rpm, at least that's what they usually do to my A3 TDI. Perhaps I'm being lucky and they don't push it to hard while being cold... As I live near by a test center, the car never gets to heat properly. But I would be surprised if the tester had that careful thought... ;)

 

Dusky, relevant point you got there... I checked my dizzy and its a "41030 K" and below it's written "11 70". I believe it's a 998 one, according to haynes manual.

Is it worth changing? If so, what would you recomend? I am about to order some parts from minispares, I could order a dizzy too.

[carbon]

It will be possible to set up the 41030 distributor you have to get reasonable results. If it is still standard then this will have 12 degrees of mech advance built in (ie 24 degrees at the crank) so setting up with static timing of 10 degrees would be reasonable starting point. 41030 also has a 5/11/7 vac advance can, good for road use.

 

I've never set up a modified 1100, but have seen comments that they have quite specific ignition timing requirements. There's no point in getting another distributor unless you know the exact specification you need to ask for...

 

PS. when setting up mixture on the carbs and testing ignition timing make sure the engine is running at stable temperature, if your water temp gauge is accurate this should be reading between 80C and 90C.

[maxmaniac]

 Nice, then!

 

Yeah, before any set ups, I usually go for a small run to get it to warm up nicely.

 

Actually, as long as the thermostat opens (82 C), mine rarely heats up more than 75/80 C.

I guess this is because the weather is a bit cold now, +- 10 C; in summer temperature rises to 35/37C and he runs a bit hotter.

 

While driving in highways, I close the heating inside to try to maintain a higher temperature on the engine, but it's a bit pointless as he just cools down everytime.

My main concern is when I stop the engine and the water pump stops... In this case, temperature rises to about 100C.