Keeping it BMC

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chrismog
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Keeping it BMC

Post by chrismog »

The 1098 traveller I've had for years is getting a few upgrades.
The first is the brakes. Its getting the marina pedal box conversion with servo assisted disc brakes at the front, 9 inch drums at the rear will remain, prob will servo assist them too although as yet undecided.

As for the engine, I'm not going for a 1275 lump. I think I can get enough power out of the 1098 with a good choice of cyl head. I have David Vizard's book and have read the relevant bits, but finding a decent 12G295 is becoming more and more difficult. Besides I've read on here that a 12G940 is as good anyway? Advice here appreciated, but I'm not after huge improvements in performance, just modest upgrades really.

Carbs - I've a set of twin 1 1/4 SUs and a single 1 1/2 SU. The 1 1/2 is on there at the moment, Burlen in Salisbury helped me jet it correctly for the 1098. I'd quite like to fit the twin carbs, but are they worth the hassle? Still undecided.

Gearbox and final drive - I'm after just a slightly higher ratio really, ie comfortable at 75mph as opposed to 65mph which is all you will get from a standard 1098 set up. With a 1098 box a Riley 1500 diff looks like the way forward (if can find one) but is the torque sufficient from a modestly uprated 1098 for this to be ok? I quite like the overdrive units fitted to the MGB / late TRs - worth considering? / more importantly can this be done? Has anyone put an o/d on a minor box?

Telescopic dampers are a must really, although as the suspension still needs some thought - are marina torsion bars the way forward?

Other (already done) - Mini alternator and Cooper rev counter, other smiths gauges from MG / TR

So the mods are BMC only, hence the title of this post, not interested in Ford / Fiat / Toyota mods.

I hope this post stirs a bit of discussion... does this set up sound feasible? Where's the new weak spot in all this?

Thanks in advance
Alex'n'Ane
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Re: Keeping it BMC

Post by Alex'n'Ane »

You say about 9" drums at the rear? Do you actually mean 7" rear drums as standard? I thing the wolsley or riley had 8" rear drums but I don't know of anything non ford with 9" rears?
___Anne___

chrisryder
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Re: Keeping it BMC

Post by chrisryder »

apparently, a standard 12G940 (1275) head will flow better than any rediculously modified 12G295 (1098ish) head. So much more worthwhile making that fit.

Riley/Wolseley diff is 3.7:1 which should pull ok with a well modified 1098, especially with that 1275 head.

You might get shot down for the pedal box, some people will tell you it's a waste of time. but the advantages of dual circuit brakes are very worthwhile from a safety perspective.

Carbs, twins are a waste of time, David Vizard will explain why, at great length, as only one cylinder is drawing in at a time so you're just halving the work, and it means that you're always only drawing in through that small carb. With a tuned 1098, a single 1 1/2 is good. One carb means one carb to maintain, one carb to set up, and no balancing!

Not too sure what BMC telescopics you could pinch, other than the standard tele's on the rear of minor vans and pickups.
chrismog
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Re: Keeping it BMC

Post by chrismog »

Yes I meant 7 inch drums - not 9 inch !

The pedal box - yes its a lot of work but the master cyl in the chassis leg has always annoyed me -
I could do a remote reservoir and keep it there but I'd prefer the complete pedal conversion.

Thanks for the advice on the twin carbs also...
minor_hickup
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Re: Keeping it BMC

Post by minor_hickup »

chrisryder wrote:apparently, a standard 12G940 (1275) head will flow better than any rediculously modified 12G295 (1098ish) head. So much more worthwhile making that fit.

Riley/Wolseley diff is 3.7:1 which should pull ok with a well modified 1098, especially with that 1275 head.

You might get shot down for the pedal box, some people will tell you it's a waste of time. but the advantages of dual circuit brakes are very worthwhile from a safety perspective.

Carbs, twins are a waste of time, David Vizard will explain why, at great length, as only one cylinder is drawing in at a time so you're just halving the work, and it means that you're always only drawing in through that small carb. With a tuned 1098, a single 1 1/2 is good. One carb means one carb to maintain, one carb to set up, and no balancing!

Not too sure what BMC telescopics you could pinch, other than the standard tele's on the rear of minor vans and pickups.
Twin carbs are not a waste of time. It's just a shame that the standard manifold requires a lot of work to make it flow well. It is also untrue that they go out of balance quickly, they stay in tune as long as a single carb once they're set up. A single is definitely an easier way forward. But twins are a nice period piece but need to have an unworn linkage and be matched to each other properly.

A 12g295 or 12g206 head can easily be ported to flow really well. 12g940 heads need the block pocketing and you are restricted in terms of cams you can use. I know some people sink exhaust valves to make them fit but I can't see the point in ruining what is becoming a rare head (especially larger valve variants) when 1098 blocks are so cheap and available. Personally I cannot see a good case for sinking considerable money into tuning a 1098 when a 1275 is more powerful, more torquey, more robust and tune-able; unless of course you have most of the bits to hand. By the time you add up the cost of a head, the work to make it fit (skimming a 12g295 or making a 12g940 fit), a decent cam, carb and manifolds a 1275 seems like a really good idea.

A standard 1275 with a 3.7:1 diff makes for a very useable car. Mine used to get around 40mpg and would easily cruise at 75-80 mph.
bmcecosse
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Re: Keeping it BMC

Post by bmcecosse »

Standard twin 1.25" BMC carbs+manifold ARE a waste of time - that single 1.5" SU on a good manifold is the way forward for you. You will NEVER get a 295 (or 206) head to run as well as a standard 940 head - and a little work down the exhaust throats make a very worthwhile improvement to that head too. A 'big valve' 940 is indeed best saved for a 1275 engine - and it is very simple to sink the 940 exhaust valves IF NECESSARY. Often there has been some exhaust valve recession anyway - and no further sinking is necessary. Certainly no 'pocketing' required for up to MG Metro camshaft - which works well in the 1098 engine - although the standard AEA 630 is pretty good anyway with the 940 head.
Don't rush in to tele dampers - the lever arms are just folded up tele dampers anyway.... Fill them with decent oil and they work surprisingly well for little cost outlay. By far the best handling improvement comes from wider wheels and tyres.......
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mike.perry
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Re: Keeping it BMC

Post by mike.perry »

I have used the same criteria, all BMC, although I have gone a slightly different route, 1275 Midget engine and box and a 3.9 diff gives me a compromise between accelleration and cruising. The twin 1.25s are OK if you can be bothered to set them up properly but probably no better than a big single, however they do give the engine that classic look. Exhaust is an LCB system, I would like to remove the back box to restore the Minor sound on overrun but I am not to sure about the noise.
Front brakes are BMC sourced, 9 in from the Wolseley, there must be a lot of Wolseleys with no front brakes, and the wide wheels are 13 ins I believe from a Midget and fit the smaller Series MM hub caps
I have retained the manual clutch lever on the diaphram clutch plate by a simple modification to the linkage.
The only non BMC sourced items are the front seats which are I believe MG Maestro so are BL items
Last edited by mike.perry on Mon Sep 05, 2011 11:09 pm, edited 1 time in total.
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bmcecosse
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Re: Keeping it BMC

Post by bmcecosse »

As hinted earlier -using twin 1.25" SUs limits each cylinder to breathing through ONE 1.25" carb -there is no worthwhile cross flow in the manifold - in fact it's shape at the junction with the straight run in from the carb actually spoils the straight run air flow..... Using a single 1.5" SU on a GOOD manifold - allows each cylinder to breathe through a 1.5" carb, which is obviously a rather better arrangement. You must remember that each cylinder breathes independently of the others - they aren't all competing for the airflow through the carb. But as Mike says - the twins do give a 'period' look.....
Last edited by bmcecosse on Mon Sep 05, 2011 9:05 pm, edited 1 time in total.
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chrismog
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Re: Keeping it BMC

Post by chrismog »

Thanks for the replies all - interesting reading. The twin carbs would give the 'period' look, but I will certainly hang on to the 1.5" SU also. The wider rims and tyres have me thinking also. I'm not a fan of marina rims - I prefer the standard minor look. With van rims being like hen's teeth to find, has anybody widened a standard set of minor wheels?
cheers
Chris
bmcecosse
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Re: Keeping it BMC

Post by bmcecosse »

There are some 'banded' steel wheels around, it's also possible to fit Minor wheel centres in to the wider rims from later cars - Vauxhall 14" wheels for example.......
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chrismog
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Re: Keeping it BMC

Post by chrismog »

Ahh yes that would be an easier way round it, I'm tempted to look into that. Although the title of the thread would have to change to 'Keeping it BMC and Vauxhall' :D
chrisryder
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Re: Keeping it BMC

Post by chrisryder »

Not sure whether they still do, but Minor Developments certainly used to do some wide wheels that were 14 inch toyota (i think) rims with the centre cut out, and a Minor centre carefully (!) welded in place. Meaning you got wide rims for wide tyres, fitting minor hubs, and taking minor hubcaps.

The only downside is that they aren't strictly BMC.
bmcecosse
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Re: Keeping it BMC

Post by bmcecosse »

And - I worry that the thickness of the Minor wheel centre wasn't designed to take the loadings of the wider rim and wider tyre.... :o
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