Ask the ex­pert

Your Mini ques­tions an­swered by Keith Calver

Mini Magazine - - Mini Tech -

DOWN ON POWER

Q I have a 1977 Mini Club­man 1098 Es­tate, still fit­ted with its orig­i­nal en­gine and gear­box. Both ap­pear to be in good con­di­tion, with the en­gine us­ing no oil. How­ever, at any­thing over 60mph it seems to be work­ing ex­tremely hard. I’ve set the tim­ing as per the work­shop man­ual, and I think the fu­elling is right too. How­ever, it’s just gut­less. I know it’s not a Lo­tus, but I don’t re­mem­ber other Minis be­ing this wheezy. Would some tun­ing parts help? What else would you rec­om­mend? A friend sug­gested it’s down to valve seat re­ces­sion, but surely it would smoke if so? Steve

A Be­fore fit­ting any form of tun­ing up­grades, you need to make sure what you have is fit and healthy. To do that you need to do a cou­ple of things – get a leak-down test done and if that looks good, get it set up on a rolling road.

The leak-down test is used to de­ter­mine the health of each in­di­vid­ual cylin­der. This is done by set­ting each cylin­der in turn on its fir­ing stroke with the pis­ton at top dead cen­tre and both valves closed. A tube with a threaded adap­tor at one end is screwed into the spark plug hole, while the other end has a cou­pling that at­taches to an air line so the cylin­der can be pres­surised with com­pressed air. The main sec­tion of the equip­ment has two gauges that show the air pres­sure be­ing ap­plied, and the amount of air be­ing leaked out by way of a per­cent­age. Up to 10 per cent leak­age is pretty good, 20 is OK and up to 30 con­cern­ing. More than that, and you’ve got ma­jor is­sues. It is not just the gauges that re­veal any prob­lems; air heard es­cap­ing can lead you to the spe­cific prob­lem. If heard com­ing out of the car­bu­ret­tor, it’s the in­let valves not seal­ing. Out of the ex­haust, it’s the ex­haust valves not seal­ing. If it’s out of the rocker cover and dip­stick tube, the rings are not seal­ing as they should.

Get­ting the car set up on a rolling road will op­ti­mise fu­elling and ig­ni­tion, and give a power out­put read­ing. Whilst rolling roads rarely pro­duce ac­tual and real per­for­mance read­ings, the fig­ures ob­tained can be di­rectly com­pared with other sim­i­lar units run up on it to give some idea of the health of the en­gine.

Be­fore head­ing off to the rolling road though, there a cou­ple of things to check and sort. Make sure the ig­ni­tion sys­tem is in good health – so points, con­denser, ro­tor arm, dizzy cap, spark plugs and plug leads. I’d like a pound coin for ev­ery en­gine I have

looked at for some­body for a sim­i­lar com­plaint, only to find the plug leads are so de­graded they are on the point of stop­ping a spark get­ting to the plug!

The other thing to check is the oil – fore­most the oil level. I have had a hand­ful of folk come to me over the years say­ing their en­gines won’t rev and feel flat, which turned out to be be­cause of ex­ces­sive oil in the gear­box! It is sur­pris­ing what the ef­fect of an ex­tra litre in the sump can have. The ex­cuse was usu­ally ‘well, I put ex­tra in be­cause it seems to be get­ting through it quickly’. No joke.

RE­STRICTED SPACE

Q My front seats won’t go back any fur­ther as they are hit­ting the rear com­pan­ion bins, and this is caus­ing me ter­ri­ble pain as I drive. Are the bins struc­tural, or can I cut them out? Would I need a rear ‘cage? Maarten

A The com­pan­ion bins are not at all struc­tural, so re­mov­ing them will not cause any struc­tural strength to be lost. You just won’t have any­where to store the six­packs. Con­se­quently a rear rollcage sec­tion is not re­quired. And as daft as this may seem, fit­ting any sort of rollcage increases your in­surance pre­mium as they see it as be­ing done so you can ‘race’ the car. It’s a bit like the is­sue with fit­ting win­ter tyres in the win­ter – very much a sen­si­ble safety move, but not part of the car’s orig­i­nal spec­i­fi­ca­tion.

The way I have dealt with this in many of my Minis is to make seat brack­etry that moves the whole seat as close to the hand­brake/car cen­tre­line as pos­si­ble. This al­lows the seat to be moved back quite a long way with­out foul­ing the com­pan­ion bin.

FRONT-MOUNTED RAD

Q I read a few months ago that a front-mounted ra­di­a­tor was fit­ted to MPi Minis to qui­eten them down. I’m try­ing to cre­ate a nice re­fined Mini us­ing a ‘93 Mini May­fair as a ba­sis. I’ve al­ready fit­ted Smootha Ride and loads of sound dead­en­ing, so this seems like a good idea to en­hance re­fine­ment. How would I go about do­ing this? Can I just fit the brack­ets from an MPi or is there more to it? Ron­nie

A The front-mounted ra­di­a­tor to re­duce noise has prob­a­bly a great deal more to do with do­ing away with the me­chan­i­cally-driven fan rather than ‘block­ing’ any noise com­ing out from the en­gine bay. The test used to de­ter­mine such noise lev­els are drive-by recorded by some­body road-side, not in the cabin. It is true a front-mounted ra­di­a­tor is go­ing to be more ef­fec­tive than a side-mounted one as it is in pretty much undis­turbed air flow, but it is lim­ited in its ca­pac­ity be­cause of the avail­able space to fit it in. Whether you need a more ca­pa­ble cool­ing sys­tem will de­pend on the power ca­pa­bil­ity of your en­gine. You have not said whether your Mini en­gine is stan­dard or mod­i­fied. If stan­dard, or mildly mod­i­fied, the MPi rad would work OK. More than that it will strug­gle. The side-mounted set-up has been around so long that some pretty ef­fec­tive ra­di­a­tor types have been de­vel­oped to cope with some se­ri­ous per­for­mance out­puts. Used with the stan­dard plas­tic fan they do not de­velop all that much noise

“The side-mounted set-up has been around so long that some pretty ef­fec­tive ra­di­a­tor types have been de­vel­oped...”

“The re­sult is a greater vol­ume of cleaner in­com­ing charge of fuel and air and so more power...”

that can be heard in the cabin. Con­se­quently I do not con­sider it a worth­while change, es­pe­cially con­sid­er­ing all the re-plumb­ing and elec­tric fan fit­ment needed to make it op­er­a­tional.

STAIN­LESS PIPES

Q I have a 1993 Mini Cooper SPi that I’m con­sid­er­ing fit­ting a new ex­haust to. It’s cur­rently stan­dard but with a cat­back stain­less RC40 Mil­len­nium sys­tem. I’m look­ing to make the whole thing stain­less apart from the cat, in­clud­ing a stain­less LCB but keep­ing the in­jec­tion in­let man­i­fold. Will I no­tice an in­crease in noise by do­ing this? And will I have prob­lems with the Lambda sen­sor only sam­pling from one pipe on the LCB? Roland

A There will be a slight in­crease in noise go­ing with the stain­less steel LCB be­cause stain­less steel ‘rings’ more than mild steel does. The shock waves/ pulses in the ex­haust sys­tem act in a sim­i­lar man­ner to tap­ping the me­tal. This can be negated by wrap­ping the man­i­fold pipes in ther­mal heat wrap. There is a big bonus to do­ing this aside from damp­ing the noise down, it will im­prove per­for­mance by main­tain­ing the heat of the ex­haust in the pipes. This keeps the ex­haust gas mov­ing faster, which helps ex­tract more ex­haust gases out of the com­bus­tion cham­ber. The re­sult is a greater vol­ume of cleaner in­com­ing charge of fuel and air and so more power. And on top of that, it will help re­duce the un­der-bon­net tem­per­a­ture, which means a cooler in­take charge and also helps im­prove per­for­mance. Win­ning all the way.

As for the Lambda sen­sor lo­ca­tion, as long as it is mon­i­tor­ing more than one cylin­der there should be no prob­lems. I be­lieve most LCBs have the sen­sor boss fit­ted to the se­condary down pipe for the outer two cylin­ders.

WIND­SCREEN FIT­TING

Q When fit­ting a wind­screen, is it bet­ter to put the seal on the car and then put the glass in, or put the seal on the screen and fit it to the car as one? Is the string method rec­om­mended? Alex

A This is one of those ques­tions that would di­vide a car-park full of Mini own­ers. I al­ways fit the seal to the body, then the screen to the seal. I have tried the other way on sev­eral oc­ca­sions to see if there is a ben­e­fit, or some­thing I have over­looked. Noth­ing ob­vi­ous floats to the sur­face, other than a real de­pen­dence on the qual­ity of the string used. Fit­ting the seal to the body, then the screen to that re­ally only re­lies on the pair of hands do­ing the work, so more of a known fac­tor. I use a cou­ple of strips of mask­ing tape to keep any re­luc­tant-to-stay-put up­per seal sec­tion to the top of the frame, fit the screen’s bot­tom edge into the seal, the use a suit­able tool to pull the seal out around the screen edge all round. A Snap-On Tools split-pin puller has been ace for this as it’s prac­ti­cally the per­fect shape for the job. A lit­tle wash­ing up liq­uid used as a lu­bri­cant works very well and is very easy to clean off after­wards.

A rolling road ses­sion can help with poor per­for­mance.

Retro-fit­ting a front-mounted rad would be a tricky task.

Can rear bins be re­moved?

Opin­ions dif­fer when fit­ting glass.

A stain­less LCB will be slightly louder.

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