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[Dr Schnauzerton]

I have a 1963 minor fitted with a 1380 engine and toyota gearbox. It never seems to be in the right gear and can struggle on hills. The rear axle is a 1.8 marina unit. How can I change the gear ratios to help power please?

[bmcecosse]

Welcome to the forum! Hard to imagine a 5 speed box won't have the 'right' ratio! After all - there is an infinite variety of hills - all with different gradients - it must fit some of them at least some of the time! Perhaps the problem is a very restricted power band on the engine? What spec is it ? What cam is fitted ? And we really need to know the current ratio of that Marina axle ?

[Jefftav]

Welcome.
The 1.8 Marina diff might be too highly geared for your gearbox, I think with this engine the Marina 1.3 diff is the normal one to fit but I am not sure if the 1.3 diff will fit the 1.8 axle? Also check that the brakes are realeasing and that the clutch isn't slipping.

[Dr Schnauzerton]

Thanks for your input, and thaks for your welcome!

The car was bought with the parts fitted and all I have to go by is a spec sheet from the builder of the car.

It is being worked on by a local MG specialist and he is trying to gat the best set up of the engine using the info supplied. I'll keep you posted of developments.

Can I 'just fit' an MR2 engine?

[Dr Schnauzerton]

It's got 15" wheels also which I know won't help.

[rayofleamington]

Welcome to the forum! Hard to imagine a 5 speed box won't have the 'right' ratio!

It hard unless you've driven one like that!

Something like 4.22:1 (diff ratio) should be about right based on your engine, box and wheels.
I've no idea what you've got in your axle though, and there's no guarantee that it is standard Marina spec either.
Also there was more than one type of Marina axle but i think the other type was limited to vans.

[charlie_morris_minor]

the axle ratio for 1.7 / 1.8 / 2.0 marina / ital is 3.6, unless it was marina 1.8 auto in which case it was 3.3. The 1275 axle was 4.11 for the marina and 3.9 for the ital

with my old modified moggy 1275 A+ engine, ital / triumph OD box, i found the 3.9 ital axle ratio matched the set up perfectly when fitted with the standard moggy wheels, as for 15inch wheels it depends on the tyres fitted i.e. what is the overall rolling radius of the tyre?

and no you can not just fit the 4AGE engine from an MR2 you need to do some bulk head mods as every thing gets very close apparently...if you are thinking of doing this mod do a search on the aussie moggy sites as fitting the 4AGE engine is popular in that part of the world

[bmcecosse]

Let's see the engine spec! Particularly - the cam used.

[Dr Schnauzerton]

Ok. The engine came from a Marina 1275 it was stripped crank reground and polished new shells new conrods it was bored out to 1380cc with amiga flat top pistons piper 296 cam roller rockers with a 1.5 lift. With a single 450 webber. Also a alldon race system ignition system.

This info is from the ebay listing 2 years ago.

Hope this means something to somebody.
All help is welcome. thanks~

[bmcecosse]

Ahh - well there's the problem - it's almost a 'full race' engine - so will have a very narrow power band. The 296 cam used with high ratio rockers will make it VERY peaky. You could fit ordinary rockers and that would help slightly - and of course the set-up of the 45 weber will be all critical. It will go almost as well on a single HIF44 - and be far more 'drivable' because of the variable choke of the SU carb - and probably have far better economy too!

[Dr Schnauzerton]

I see, I'll pass this info on to my mechanic and hope he can make sense of it all.
Thansk everyone for your help.

[Dr Schnauzerton]

I'm watching a marina 1.3 axle on ebay. Will fitting this help or should we change a few engine parts to widen the power band?

[MarkyB]

Change engine parts.
A narrow power band doesn't make for a good road car.

Changing the axle ratio is only going to change where you hit it, not it's width.

Maybe sell the engine to a racer and then buy something road orientated.

[bmcecosse]

It's an engine out job to change the camshaft - so try standard rockers and a single HIF 44 first!

[Dr Schnauzerton]

What is the engine worth do you think?
The bloke who built it says he spend 3K on it?

What will I replace it with?

[bmcecosse]

I doubt anyone will pay £3k - the provenance of exactly what was done to it would need to be very well documented. Sold complete with the weber carb - should fetch £600/800 - something like that - IF it's in good condition - excellent oil pressure/not burning oil/no smoke/fume at the filler cap. Replace with a standard unmodified 1275 engine.

[Dr Schnauzerton]

How much of a job is it to change the cam, I won't be doing it myself and would I replace it with a normal cam or a 'fast road' item?
All my efforts so far, with changing the rear diff have helped but only slightly, now the plugs are getting choked up and the carb is smelling of petrol as it's never running properly.

Thanks

[IslipMinor]

I have a 1380 and Toyota 5-spd gearbox, but the rear axle ratio is 3.9, plus a Piper 270 cam (276° duration), 1.5 rockers and HIF6 SU carb, so a very very good spread of torque (max 108 lbf. ft) and power (112 bhp) . 5th is a very usable gear indeed - rarely need to change down on the motorway, not even for the hills.

Combination of maybe too high a rear axle ratio, definitely the wrong cam and not helped by the Weber carb.

What is the axle ratio? To check, jack up one wheel at the rear, note the number of turns that the prop shaft needs to give 2 (two) complete turns of the jacked up wheel, the number of turns that the prop shaft makes is the diff ratio. anything more than 3.9 is really too high.

If changing the cam, the followers must be changed at the same time, so afraid that does normally mean the engine has to come out. An alternative is to drain the water, undo all the head and rocker shaft nuts, remove the rocker shaft and pushrods and drop the sump. Then using 8 telescopic magnetic pick-ups (2lb with 6mm magnet, 99p each on eBay), use them to lift the cam followers and hold them up with a clothes peg. Remove the cam, change one follower at a time from below and hold back up with the magnet and clothes peg, replace the cam, re-assemble the top end, re-torque etc.

If the axle ratio is OK, it might be worth trying an SU HIF carb first, but I doubt it would really make enough difference.

I would suggest a fast road cam, the Piper 270 is very good.

What plugs are you using? NGK BP7ES or may be BP8ES would be the right grade.

Where are you located?

[Dr Schnauzerton]

thanks for all your advice. I will pass this info on to the man with thge spanners. The rear diff currently installed is from a 1.3 Marina. I replaced the 1.8 marina unit that came in the car.

Do you think definatley change the carb first and see if we get away with it or just go all in?

I live in sunny Eastbourne.

[bmcecosse]

Your two top priorities (and I told you this before!) are to remove the daft high lift rockers (easy to do) and the Weber carb - fitting a single HIF 44 SU carb. This will make the car MUCH more tractable. It's an engine out job to change the cam - so this should be a 'last resort' . Yes - the method above should work (I have suggested it to others in the past - but never done it myself) and at least on the Minor it's not a disaster if a follower drops down (It very much IS on a Mini!!). However there may be oil pump complications if the new cam is not the same drive as the old cam - and you won't know that until you take it out!