67 replies to this topic

[Aaron3]

Im having the same problem at the moment, my revs are high on tick over so I suspect the ignition is to far advanced its only happened since Ive painted the engine block, Ill post my findings for you tomorrow when I have a play around it could be a simple fix for you.

[absx2]

I once had a painfully slow mini 1000, well actually I still have but thats due to the 2.9:1 diff but that's another story :)

 

Anyway after a full check over everything was in top condition, timing spot on etc I changed the old but very solid exhaust for a standard replacement part and found the missing 15 bhp. The internals had corroded and blocked the exhaust !

I have pulled the heads from a few low milage town runabouts where the carbon on the exhaust valves had taken up 3 of the 5 mm valve lift.

 

Timing is another problem as minis are supposed to run on 97 ron unless they are low compression models so the ignition gets retarded to stop detonation when using lower grade fuels to the point where the engine is lifeless.

 

Aaron3 it sounds like you have knocked the vacuum pipe off.

[Cooperman]

Timing and too-end mixture?

[ukcooper]

just learn to drive like it is any fool can drive fast , but take a driver to know when stop and go round a bend ....

then a gain drop a R1 in it will go a lot faster then simples ..

[TheFabMini]

just learn to drive like it is any fool can drive fast , but take a driver to know when stop and go round a bend ....

then a gain drop a R1 in it will go a lot faster then simples ..

Like I said I plan on zooming around Norfolks B roads more than anything so top speed isnt really my main concern

The car was off the road since 1999 until last month so who knows whats built up... probably got a mouse nest in the exhaust.
The engine number doesnt match the log book so who knows the true history...
Eitherway I find it amusing that I thought I was carefully driving at 50mph to be kind to the car getting back on the road. Put my foot down for the first time and it didnt even reach 60 🤣

[ukcooper]

well 50mph is far to fast when ya crash or hit some person I know about crashing luckily haven't hit a thing so far, I hear the old school driver allways drove with there foot to the floor and just drove round each corner propa driving in my book but ya gota learn some where and slower the better . I cant drive like I used to head wont take it so I'm jealous off ya . have fun be safe..

[1984mini25]

I once had a painfully slow mini 1000, well actually I still have but thats due to the 2.9:1 diff but that's another story :)

 

I can easily do above the national motorway speed limit in 3rd (std 998, 2.9 diff), further acceleration in 4th though is a combination of painfully slow/or just simply not happening.

[Anthony30]

My 998 was a revvy bugger, and was pretty quick on a nice day, with hardly any wind.  It/she did have a few upgrades on the top end though. 1293 turbo should be 'adequate'.    

Edited by Anthony30, 23 April 2018 - 09:12 PM.

[timmy850]

My tired old 998 will get up to nearly 70mph. However with the short 3.76 diff ratio it's just about floating the valves nearing 5000rpm.

 

At 60mph (4000rpm) it goes up most hills and still has some pickup as it's right in the thick of the powerband.

[Cooperman]

There are several things you need to check.

 

1. Measure the compression figures in each cylinder. Use a gauge, remove all the plugs and put a bit of light oil in each bore. The throttle needs to be fully open when taking the measurements. You should have a minimum of 150 psi on each and they should all be within 10% of each other.

 

2. Ensure that the throttle is fully open when the pedal is right down. Top up the carb dashpot with light oil, 3-in-1 or air tool oil. Check that the carb piston rises freely using a finger in the carb inlet port. The air cleaner needs to be removed.

 

3. Set the valve clearances to 0.012" cold.

 

4. Clean the distributor points and set them to 0.015".

 

5. Set the ignition timing static to the manufacturer's recommended figure for your engine. It will be around 6 degrees BTDC.

 

6. Clean the plugs and set them to 0.025" gap (or, ideally, fit new plugs).

 

7. Fit a new air cleaner element.

 

One other problem could be failure of the mechanical or vacuum advance in the distributor to work correctly. It is not unknown for the bob-weights at the bottom of the distributor to get stuck if the car is not used and then it will not fully advance at higher revs. The vacuum advance can be tested by sucking on the pipe, but to check the bob weights the distributor needs to be removed. I do recall having a huge problem with a restored Mini Cooper and I tried everything until, finally, I took out the distributor and the bob weights were partially stuck. That car would start and run smoothly until I tried to make it go a bit, then it 'bogged down' and felt very sluggish. If necessary clean the bob weights and lightly oil them with engine oil. Mark the correct distributor position before removing it.

 

When it is running better you can do a 'Redex' tune-up. Get it revving and pour some Redex into the carb inlet whilst revving it. Do this and lots of bits of carbon will come out of the exhaust pipe. This is an 'old-school' method, but it was done a lot in the '60's. The alternative is to remove the head, de-coke it and re-lap the valves in. 

 

A 998 should be capable of running at an indicated 75 to 80 mph on a level road all day long, although some with the very high FDR are reluctant to get to that sort of speed. A 3.44:1 or 3.76:1 is better and don't worry about the high revs. It is an old design of car and they always revved when cruising. Use up to 6000 rpm when accelerating hard and run at up to 5000 rpm cruise revs and through the gears.

 

Use decent petrol, not supermarket 'weasel p**s'. I would go for a 97 RON petrol, Shell or BP.

 

That's given you a few little jobs to do .  I hope this helps.

[TheFabMini]

Thanks for the reply. Guess Ill pop to Halfords and get a compression tester!
If my compression is low, do I just cry in the corner and give up all hope?

[timmy850]

Depends. It could be a quick and easy or expensive fix but itll give you a clue where to check next. It could be something like:
Head gasket
Piston rings
Valves

[Cooperman]

If has low compression on one or more cylinders the first suspect would be the exhaust valves and that is easy to fix. If it was the piston rings it would be filling the rocker cover with smoke, so take off the oil filler cap and run the engine at tickover. It will likely 'puff' a bit but not excessively.

Go through my list thoroughly and it should go well. If the carb is ok the mixture should not be far out and a final set can be done later.

If you do take the head off it is wise to change the valve stem oil seals at the same time as re-lapping all the valves in.

For more help just ask.

[TheFabMini]

If has low compression on one or more cylinders the first suspect would be the exhaust valves and that is easy to fix. If it was the piston rings it would be filling the rocker cover with smoke, so take off the oil filler cap and run the engine at tickover. It will likely 'puff' a bit but not excessively.

Go through my list thoroughly and it should go well. If the carb is ok the mixture should not be far out and a final set can be done later.

If you do take the head off it is wise to change the valve stem oil seals at the same time as re-lapping all the valves in.

For more help just ask.

Thanks, compression tester ordered so should be able to let you know that one within the next couple of days
But will go through some other parts on your check list.
When I purchased the car it was a non runner.
To get it going I have replaced
Spark plugs
Distributor car
Rotor arm
Head gasket
Oil/filter

And I think thats about it engine wise... the last owner never got it going so I dont know the history in terms of why it was ever taken off the road for so long.
Fingers crossed its simple as I dont want to take it all to bits again yet!

Oh and Ive only been using shell v power with some car lube lead additive. Fresh petrol about 3 weeks ago so shouldnt have gone bad yet

Edited by ChrisRuffell, 24 April 2018 - 04:43 PM.

[Cooperman]

Personally I suspect that the timing is not set correctly at idle, or the vac advance is not working properly.