Fast Marina Magazine

Lock it in first gear and floor it up a hill. It should fly up but if it has the problem I had with my Rover and going by what you've done to the engine so far I would say it's definitely the auto box.

The Torque convertor is a fluid flywheel, to partially disconnect the drive and to multiply torque when the output rotational speed is so low. The pressure is supplied by the front oil pump fitted behind Torque Convertor. Gear changes are controlled by the valve body. Engine load is measured by the kick down cable and road speed by the hydraulic governor. These items move the valves in valve body to lock the brake bands and clutches together to give the required gear. The selector lever is also connected directly to the valve body, to give initial valve positions for forward / reverse drive and neutral also connected is the parking prawl. This engages with the rear most drum to give a mechanical lock. Its more complex, but tried to give a simple explanation as to how a auto transmission works.
Dave

Morris McKinnon wrote: Wed Jun 28, 2017 6:35 pm Lock it in first gear and floor it up a hill. It should fly up but if it has the problem I had with my Rover and going by what you've done to the engine so far I would say it's definitely the auto box.

Its not the transmission. The automatic gearbox leaks ATF all over a drip tray placed underneath it because somebody else has had the sump off and put it back with the same gasket. Its another job I've got to sort out but it can wait until the car is running properly. The car has been down on power the whole time I've owned it, from mid April 2016, and I didn't start trying to do any maintenance and adjustments until after I'd talked to people at the Marina Nationals at Quorn last year, which my car barely made it to despite Quorn being on my doorstep. That 30 mile round trip made me realise just how bad it was. Then as soon as I started trying to tune things up, and setting them by the book to the best of my abilities, the car got worse. To the point of being unusable. This has NEVER happened to me before. Recently I found the distributor cap had a crack in it when the car was off the road over winter, and I thought that was a stupid thing I'd missed that was responsible for most of the running problems I'd had, but the fact that the car still barely runs in spite of everything I've renewed suggests plenty of problems lay elsewhere anyway, and maybe the cap even got cracked when I took it off to get at the failed starter motor. The auto box holds the gears when I have been able to drive it. Clearly with leaks, I can't say my auto box is perfect, but its not responsible for the poor engine running, incorrect distributor function or high hydrocarbon readout. For a long time now I've needed someone who knows what they are doing to have a look at it but there were so many other things wrong with the car that it wasn't fit to give to anyone without ending up with a massive bill. Now that for the most part it is just down to getting the engine running smoothly, and it's already in someone else's hands, as far as I'm concerned I'm not having it back until it is right.

Ha ha! Distributor Doctor ain't got one for mine! My man's got one coming in from somewhere else for him to look at but if it isn't right, my dizzy has to go away for a rebuild.

Surely an MGB Lucas 45D would be near as dammit? Hells, I had an Accuspark one with a generic "MGB" advance curve in my 1.8 for years and that ran well enough despite a softer cam & single carb (and naff all compression). Certainly top speed was limited by crankcase pressure at high revs, not the engine's ability to rev!

Imagine that's cheaper and easier than getting yours rebuilt, especially when it might not be the original anyway.

Accuspark ones are about £40 and work well.


Sent from my iPhone using Tapatalk

The info I've got at the moment is that he's sourced a secondhand dizzy that's coming in tomorrow. I'm uncertain if he's still converting it to electronic ignition now it's down to used parts, but even if its a case of making one good one out of two, I'm happy that someone has given me a definitive answer, at least as far as the ignition is concerned, as to why I couldn't time the car correctly right from the start. It is possible there was never a good reason to get my carbs rebuilt, on the other hand, so much on this car has been mucked about with badly there's no telling whether the carbs were correctly jetted or not. Matt, I don't really understand why my car is supposed to have an MGB cam, yet places like Rimmer and Moss specify distributors for MGBs that have different serial numbers to that on my car - which I believe is the original. But with the amount of grief this car has given me I'm not really in much of a mood for a distributor that's 'nearly' right. True time will still tell how it turns out, but even correct used bits sound better to me right now than incorrect new ones.

Fair enough! I thought you may struggle to source a good 'un but sounds like your man has come up trumps.
I think there's multiple subtly different advance curves for different applications. Reality is with modern fuels, engine wear, different spark plugs etc etc I suspect it makes sod all difference so long as it's somewhere halfway handy, unless you are going racing anyway.

But if you've managed to get the right one then happy days

Had a look on Autodata before I left work. On MGB vs Marina TC the 45d distributor has a Mechanical advance curve that is identical, base dynamic timing at idle is set 2 deg different. Vacuum advance curve slightly different. But in real world as PHUQ says with modern fuels makes no odds. Paul Dapper has new 13H9694 distributor listed on ebay eBay, item number:360318558221. If your Vacuum can diaphragm is any good a very big if you could swap it and have what you had when car was new.
Dave

I put an Accuspark with matching coil in my 1.8 and it runs and performs very well, and both my 1.3s. Got them all new off ebay.

I'll have a look on ebay. I had a look at the Accuspark website on my phone when I was still at work earlier and couldn't open anything on distributors that made much sense.

Dave, a question to satisfy my technical curiosity - why, if the engines in an MGB and Marina TC are essentially the same, would there be a need to have a base dynamic timing 2 degrees apart?

My opinion is to make she same thing perform slightly different, one being a saloon car and the other a sports car. It is dome today even more so several different manufactures develop an engine. Take the PSA / MINI unit, also used by Ford. The all run different engine maps to taylor the engine to their particular application
Dave

I run an Aldon Ignitor in my MG 25D distributor, which is a Pertroix unit. (lifetime guarantee in the USA) All fits neatly inside the cap and been totally reliable tough wood. Forget who I bought it off now, but think it was Martin at Distributor Doctor.I get most of my ignition stuff from him as he has original NOS Lucas stuff, not the cheap modern copies and I always fit his Reliable Red Rotor Arms as well in my customers cars.
Dave

My 123 dizzy has 16 different curves to choose from. Kept the dyno man busy