13 replies to this topic

[myminipickup]

Hi - I'm after a little bit of advice again please :

 

I have a 1972 Mini pickup, which I have spent years rebuilding.. and I've just got it on the road.

 

I changed the engine from the original 998cc A to an early 1990s 1275cc A+ but I kept the original gearbox - which is a magic wand 4 synchro 3.44:1 final drive. I've kept the original 10inch wheels and speedo.

 

So I bolted the A+ onto the original box using a new 1275 primary gear for A series drop set - keeping the original drop set.

 

I've put a set of twin HS2 SU carbs on it, with the A+ head, keeping the original cam.

 

When I drive the Mini, it pulls really well but when it gets to about 45/50 mph, in 4th it "feels" like I need to change up another gear.. I have had it to about 60, but it again "feels" like it revving fast...I say "feels" because I have no tacho in it, so do not actually know the revs..

 

So, is this normal for a Mini? I can't remember as its been a long time since I drove one, and now I'm used to more modern cars? Or have I messed up the gearing ratio by bolting on the 1275 engine? Is so, what can I do about it?

 

For ref: Engine code of old engine: 99H387E

and new A+ engine: 12A2EJ02

 

Thanks for your help.

 

 

 

[nicklouse]

you should be able to get to speed over the speed limit with a 3.44 FD with ease.

 

2 things come to mind.

 

check speed with GPS

fit a rev counter to check RPM

[unburntfuelinthemorning]

Tha's a nice looking engine bay.  I like that you've kept the magic wand gear lever too.

 

If it's the original pick-up gearbox that'll probably be a 3.76:1 final drive.  If my calculations are correct then at 45-50 mph you'll be pulling around 3000 rev/min with a 3.44 and around 3300 rev/min with a 3.76.

 

They are a lot noisier than modern cars especially when you start going over 40 mph and definately if there's no sound deadening material - you'll get used to it.

[gazza82]

I don't know if you can still get them but in the 80s I had a cheap tacho (which was pretty accurate) that simply connected to the two coil terminals .. It was smaller than the 80mm Smiths tachos you get now and plastic making it light and easy to fit .. at one point it was taped to the column surround behind the wheel where it was clearly visible. I could also use it under the bonnet and being plastic, it wasn't an issue to hold it (or get someone else to when I was tweaking idle speeds)

 

It also meant I could remove it if I wanted and transfer it to another car (when I was fixing more "mate's" cars than my own!)

[myminipickup]

Tha's a nice looking engine bay.  I like that you've kept the magic wand gear lever too.

 

If it's the original pick-up gearbox that'll probably be a 3.76:1 final drive.  If my calculations are correct then at 45-50 mph you'll be pulling around 3000 rev/min with a 3.44 and around 3300 rev/min with a 3.76.

 

They are a lot noisier than modern cars especially when you start going over 40 mph and definately if there's no sound deadening material - you'll get used to it.

 

Thank you.

 

I am sure its a 3.44 final drive.. I will try to get a tacho and see how fast its revving.

[nicklouse]

I don't know if you can still get them but in the 80s I had a cheap tacho (which was pretty accurate) that simply connected to the two coil terminals .. It was smaller than the 80mm Smiths tachos you get now and plastic making it light and easy to fit .. at one point it was taped to the column surround behind the wheel where it was clearly visible. I could also use it under the bonnet and being plastic, it wasn't an issue to hold it (or get someone else to when I was tweaking idle speeds)

 

It also meant I could remove it if I wanted and transfer it to another car (when I was fixing more "mate's" cars than my own!)

but that is how all Rev counters work. ;)

[nicklouse]

 Capture.JPG   26.75K   4 downloads

in 4th at 45mph you are only doing  2-3k rpm.

 

something aint right.

[unburntfuelinthemorning]

I don't know if you can still get them but in the 80s I had a cheap tacho (which was pretty accurate) that simply connected to the two coil terminals .. It was smaller than the 80mm Smiths tachos you get now and plastic making it light and easy to fit .. at one point it was taped to the column surround behind the wheel where it was clearly visible. I could also use it under the bonnet and being plastic, it wasn't an issue to hold it (or get someone else to when I was tweaking idle speeds)

 

It also meant I could remove it if I wanted and transfer it to another car (when I was fixing more "mate's" cars than my own!)

I had one of them.  It wasn't great but better than nothing. 

 

Here's one:  http://amzn.eu/013sgpS

Edited by unburntfuelinthemorning, 22 June 2018 - 10:51 AM.

[unburntfuelinthemorning]

Capture.JPG

in 4th at 45mph you are only doing  2-3k rpm.

 

something aint right.

I think he's just forgotten what old vehicles were like.  He says it "feels" like it's revving high - doesn't mean it is.  Maybe he's mistaken second gear for fourth!

[robminibcy]

They do rev hard with a 3.44 changed my 79 mini to a 3.1 to try and drop a few revs on the motorway.

[Spider]

Do you think it might have a slipping clutch?

[unburntfuelinthemorning]

Do you think it might have a slipping clutch?

There's a thought, but wouldn't the revs change substantially without a corresponding change in road speed when accelerating?  Maybe they are...

[myminipickup]

Do you think it might have a slipping clutch?

 

I don't think so - I need to get a rev counter and see how fast it is actually revving - perhaps its just because its noisy

[gazza82]

 

I don't know if you can still get them but in the 80s I had a cheap tacho (which was pretty accurate) that simply connected to the two coil terminals .. It was smaller than the 80mm Smiths tachos you get now and plastic making it light and easy to fit .. at one point it was taped to the column surround behind the wheel where it was clearly visible. I could also use it under the bonnet and being plastic, it wasn't an issue to hold it (or get someone else to when I was tweaking idle speeds)

 

It also meant I could remove it if I wanted and transfer it to another car (when I was fixing more "mate's" cars than my own!)

but that is how all Rev counters work. ;)

 

 

I know but I think some are wired in series to the coil/distributor .. this had the advantage that you could simply connect black to -ve and red to +ve on the coil terminals ... and less chance of any shorting if you touched the body of the tacho to anything!

 

Plus it was easily packed into a bike sandle bag with a few tools to go and rescue another mate ..

Edited by gazza82, 25 June 2018 - 03:21 PM.