25 replies to this topic

[Dan]

You really need to go to a rolling road. You fit an improved head in order to allow more air to flow through the engine more quickly, that means you have completely changed the fuelling requirements of the engine. You can't just expect the fuelling to be right if you have completely changed the engine's specification.

[daniel_johno]

just been to halfords and bought an exhaust analyser aswel as a compression tester so atleast i can get my fuelling set right even though my needle will be wrong. (only cost me £40 on my trade card).

By a rolling road do you mean a company that will also adjust a carb needle? as the only guy local that done that now doesnt tune anymore which means the closest place to aberdeen i can find is about 200 miles away and really annoying.

The 2 rolling roads in aberdeen are 'blackbox' tuners so just deal in chips and jap cars.

Daniel

[Jordie]

You may only be able to set your idle.

The needle controls the air/fuel mixture through the rev range, which is only adjustable by sanding down the needle or changing it for another.

[Dan]

Tricky. You really do need to get an idea of whether the fuelling is good or not. It's astoundingy easy to blow a piston if the needle is the wrong profile. You probably will need a custom needle. You could always speak to AC Dodd at MLM, he is an amazing Mini tuner and has for years been selecting and profiling needles and customising dizzies by ear without a rolling road and getting remarkable results. He will be able to make a very good educated guess at a needle for your engine if you describe the setup to him well enough and it is well built. It still won't be gauranteed correct as he won't have seen the actual engine but will be damn close. At that point it would probably be safe to drive the car a long distance to perhaps take a weeks holiday in an area where there is a good set of rollers. AC Dodd is far better than WINSU by the way.

[daniel_johno]

ok thanks for all the input.

ill check compression then if its ok set the CO at idle then try get intouch with AC Dodd on Monday.

I have a BDL(mg metro), a ADE (stage 1) and a BGW needle at my dispense. Is there one of these that would be the safest to fit until i get a custom one?

Daniel

[Jordie]

The BDL was way too rich on my 1330cc, 286cam, mg metro head engine. I went for a BCW and its nearly spot on.

But BDL is what people "generally" say for a modified engine. The BGW will be even richer.

[daniel_johno]

did a compression test and was getting no pressure on cylinder 4 due to the rocker lock nut not being tight and it tightening and the inlet valve being constantly open.

Adjusted this set my timing again to 13 deg btdc but it would only run with the choke out. Connected up my CO analyser and it was running between 8 and 5% adjusted the mix and the idle to try get it running etween 1.6-3% as specified by haynes but it now jumps between 500rpm and 3000rpm and just wont settle and the CO wont go below 5%.

The fact that the engine hunts would suggest its rich but it will stay at 1200rpm for 10-20secs then shoot upto 3000. Could i now have a carb malfunction? The engine will not idle at less than 1200rpm without trying to shake its way out the engine bay.

I am thinking of just reverting back to my old head but now all my settings have changed ill have the same problem setting the engine up.

any help appreciated.

Daniel

[TOMMO0302]

I take it you sorted the rocker issue out? As that certinaly wouldn't have helped matters..

..i would try the richest needle you have and see if that helps. But after that, as long as the new head/rockers are all in order it really is just a case of getting it tuned to run well. You could always try one of those crypton tuners in your situation.

[blacktulip]

did u top up the carb dashpot with oil too. this might help with the tuning.

[daniel_johno]

Im going to try set it up again and makesure i have everythign right.

As far as the timing goes haynes metro manual 5 Deg for the standard compression 12HE unleaded engine yet when i was taking it below 10 deg it was almost cutting out.

Should i run 5 deg because i am using unleaded? or does the valve master i use raise its octane so i can use 10 deg.

Has anyone a link to the how to on setting up a carb for rough running (i.e. how many turns of the mixture screw etc) as mine is now way out and i would like a starting point.

Compression is 10.5 bar across all 4 cylinders and since oil and water change all is good with no mixing. Valve clearences have been set to 0.015" as instructed by minisports destructions for the cam.

Daniel

[daniel_johno]

i fitted the BGW needle set timing to 10 deg BTDC and ajusted the fuelling till i atleast got it running semi okay.

I think the exhaust analyser i got isnt too accurate but i got it reading about 3% CO

Atleast its running now and ill try get a custom needle for it ASAP.

Thanks for all the advice

Daniel