14 replies to this topic

[Pocket-Rocket]

Hi all

I have a problem with my Mini not running right. I have gone over all the electrical side of the mini starting e.g. points,timing,condenser,dizy,leads,plugs,coil cant think of any thing eles on that list. So i have keept on ticking of the things that i think it could be by going through them 1 by 1 and i have followed it back to the carb.
So i thought lets just be safe fit all new gaskets...head,inlet and outlet,carb and i did a compression test no leaks and it was the same read outs as my dads 1380!!! sweet as a nut i thought. Put the key in turned it over an we get..... the same noise as befor.
So i had the carb off and had a good look round it no problem with wear and tear. I have looked for any places where it mite be leeking in air still i cant find any...

Im now at my wits end as i have no idea what making the blowing noise. What ever is making this nosie is really making it slow very slow.

PLEASE HELP IF ANY ONE CAN.

Thank you for your time.

oh ps this is my 1st post on here so hello. *

[TOMMO0302]

Hello mate, welcome to TMF!

Are you sure its not just the induction noise? What air filter are you using and have you had it set up on a RR?

When running you could spray some non-flammable liquid on and around the carb and see if you can spot any bubbles which may make it easier to identify any leaks..

[Bass Man]

My daughters '83 Mayfair has a surprising loud induction roar, you only get it when you are giving it a bit of welly. When you say it is slow, are you comparing it to a 1380? In which case it is slow......

Couple of questions....

Have you rebuilt the carb recently?
Could be the jet is done up fully so it is sucking too much air?

When I overhauled the carb on my daughters I set the jet to the default (3 turns out I think?) and the car started fine, but as soon as you used the throttle you got a roar and no power. Initially I set the carb with the piston lift pin, this got me going, then got it right with a Colortune.

[Pocket-Rocket]

HI

Thank for the qwick reply.
You asked me if it was slow it has been since this noise has been coming out of the carb. Befor that it was keeping level with my mate 1.4 sr nover. which is not to bad. I try resetting the jet to nothing and then give it the 3 turns and see if that helps. It i havent rebuilt it since i have owned the car.
oh it has had a new needle fitted with the stage 1 kit.

You said some thing about setting the the piston with a lift pin??? I have never hear of that befor and then on to a colourtune?? do you mean the spring colour in side the dash pot???

sorry if i have the wrong end of the stick. It is good to hear from other people on this problem.

Tommo i havent had it Rolling Road tested and im runnig a Pipper cone air filter.

Thanks again

Richard

[cowboy]

may sound like a daft question but have you got all the leads on the right way around?

also what was it like before you put the stage one kit on it?

try changing your needle back to what it was before you put the stage one kit on and see what happens?

[Bass Man]

On the left side (viewed from front of car) of the carb, approached from the back between the float chamber and the body of the carb is a 'slide lifting pin', this is used to get the car to a basic level of tune. It lifts the slide in the carb by 1mm and you listen...

1) Engine dies - too lean
2) Engine revs then dies - too rich
3) Engine speed rises very slightly then dies - correct.

Colortune is the Gunson tool that gives you a direct view on the combustion cycle, you then change the mixture so you get a colour like a bunsen burner.

Did your problems start after fitting the Stage 1 kit, if so you'd be better getting it tuned on a rolling road, this will also probably highlight any other issues you may have.

Edited by Bass Man, 07 March 2007 - 02:40 PM.

[Pocket-Rocket]

Thank bass man

Ill have look at that now. I would say yes the problems did start after fitting the stage 1 kit vut in that time i have had it running like a dream.

Will post later on what i find

Thanks again

[Pocket-Rocket]

Hi again

Right I did a complet engine test. Oil, gaps ect

I found out that i have a blown head gaskit. Which i thought was abit wied as last time i did test it was fine... Well that will teach me for buying a sh!$y one from Harlfords!

Any way a new copper one is in the post and i hope that all will be fine. Oh just to help it alone i have rebuilt the carb lol
Any more problems i let you lot know!!! lol
Its like call for the gohstbusters lol

Thanks again for all your help on this.

[Big_Adam]

eeeewww, Halfords.

[Retro_10s]

Best HG is a the 'Payen' type (BK450) it's black, and has copper coloured rings round the oilways etc..

Definatly need a Rolling road. The needle will be all wrong for the fuelling in the carb. Con filters make a big noise anyway so that wont help the hissing

[Pocket-Rocket]

Well since i have found out that i had a blown H/G i gave the carb a good looking over and there is no leeks in it at which i was happy about lol
Your right Retro will most likely need a rr test. I have just got hold of some books on setting up carbs befor rr were about. Will let you know what i get out of the little blighter lol

Big Adam your dam right they suck ball big time lol

laters

[TOMMO0302]

So how did you discover it was gone? Another compression test? Strange it was OK a few days ago and not now?

[Dan]

I just read this thread for the first time and was going to say head gasket, blown between two cylinders. Glad you found out what it was.

Compression tests are a bit of a waste of time IMHO. They don't detect leaks, only a leakdown test will detect that. They also don't always detect blowing between cylinders because of overlap periods and things which mean there can be compression in a pair of blown cylinders, not for the entire power stroke but only a portion of it. The gauge reads the compression and because they don't reset it can look fine. They only really reveal major damage which can always be detected by other means anyway.

[Pocket-Rocket]

I just read this thread for the first time and was going to say head gasket, blown between two cylinders. Glad you found out what it was.

Compression tests are a bit of a waste of time IMHO. They don't detect leaks, only a leakdown test will detect that. They also don't always detect blowing between cylinders because of overlap periods and things which mean there can be compression in a pair of blown cylinders, not for the entire power stroke but only a portion of it. The gauge reads the compression and because they don't reset it can look fine. They only really reveal major damage which can always be detected by other means anyway.

Tommoo

We just could not under stand why it was still blowing. We (my dad and me) did look in to the valves not closing properly but that seemed fine. So he said about trying another compression test. So we did another test and it was really low on the centter 2. It does not pick up the blown head on tick over only when you gave it some welly. The fact is under higher stress the gaskit blows due to the bigger bang so it of with the old 1 and on with a copper 1. lol

Dan
Me dad said some thing about over lapping. I did not have a clue what he was on about lol. But it seems to make sence well at lest some of it does. This would explane why the head was blowing the mix back though the carb.

Wont take me long to get it done i would thought. A morning or so sounds about right.

Laters

[Bass Man]

There is a lot of stuff sounding horribly familar here......

I have noticed a little emulsified substance in the rocker cover. I checked the compression and it was OK, I am also losing a small amount of coolant, and I am getting this roaring sound under power......

Should I not trust the compression test?

Can I use a 'screw in' compression tester with the engine actually running?

This is a new gasket and everything was torqued in the correct sequence, why would it blow?

One thing I noticed when I put the head back, it didn't sit square, there was a 1/4 inch gap at one end between it and the block until I tightened it, is this normal?

Edited by Bass Man, 13 March 2007 - 04:33 PM.