Classic car, (A35) ignition problem

[alastairq]

I have fitted an 'electronic' distributor to my '67 US Ford inline 6 [200 cu in].....more out of a need to match the distributor type to the carb....cheaper than going the other way around.

The distributor [from the US] uses the '70's GM technology for ignition [HEI?}...the difference being, [for space reasons] the distributor doesn't supply the HT.....[GM units were completely built-in...having no centre [king]  HT lead, and no external coil]......on my unit....to reduce the physical size of the dizzy,the coil is external. It came with a selection of different strength, advance springs [as the Ford I6-200 engine was a generic motor fitted to most everything Ford made with wheels at the time...so ignition advance curves would be different for, say, a Bronco, or van, compared to a Mustang]..which meant a bit of trial & error finding what curve suited the car.........but the system also allows for [and recommends] a sub-1 ohm coil [i have a 0.8 ohm item], running off 12 volts  [which meant sorting a new supply]....but enable plug gaps of around 45 -50 thou or more. I am currently uncertain as to whether fuel consumption is improved, not having done an empirical check.....[and the carb is possibly slightly suspect...but can wait a while].....

But starting is almost explosive......providing fuel is at the carb.  The Ford I-6 is an old but very strong design [many say, stronger than the V8s of the time]....but suffers from the iniquities brought about by Ford's production line savings..the inlet manifold is cast integral with the cyl.head!  For tuning, the world turns to the Australians, who had the same engine....but made better advances with it. The engine suffers from uncertain fuel supply to each cylinder..the outer 2 or 3 often running weaker than the centre pots....[the inside of the inlet manifold, at each end, is pretty much inaccessible, so may have casting lumps or flaws]....the Aussies developed ally heads with separate inlet manifolds.....so the sky was the limit...especially as the block & bottom end were pretty much bullet proof. Ford used the same basic design for their base model engines right up until recently.....with size going from [my?] 200 cu in,to 250ci, right up to 400 cu in...used in their  more recent trucks. The main differences being [aside from weight] the actual height of the engine.  GM had similar designs.....the basic sixes being smooth enough, without the knuckle-skinning clearance issues of the V8s..[or the fuel consumption]..

sorry for the thread drift......

[Southern Steve]

If I remember magazine articles on A-Series tuning correctly, there were several dozen distributor variants across the range, with multifarious advance curves, vac and no vac, taco drives or not, and several points designs. Whilst they'd all physically fit in the 'ole in the side of the engine, and work after a fashion, they wouldn't necessarily work well.

 

I've never seen am A Series with a mechanical drive for a tacho, what model was that fitted too then?

 

 

Lucas devised the dynamo with a drive for the tach for the Frogeye when it came out!

[alastairq]

There is/was even a distributor that fitted an A-series [A-plus, actually] which rotated in the opposite direction!!! Painted pea green, as I recall....?  I had[might still have?] one, which came with a whole bunch [truck-load?] of spares myself and a good chum purchased in a garage close-down........we paid just  enough for a starter and an alternator for his MGB..........the rest of the lorry load was in with it.....we still have the Lucas sales racks!

 

 I recall [over 2 decades ago now]....getting all excited at getting  a brand spankers dizzy for my A-series....only to find, on fitting, the points were 'back-to-front'.........the start of my ongoing life of puzzlement, I'm afraid.

 

 

Now, either Lucas [or whoever?] made distributors, and engine makes simply designed their engine fittings around them..........or, there were some A -series that spun in the opposite direction??

 

edit...the vacuum advance pulled on the opposite side as well.....all mirror image..couldn't even salvage the points, and they were back-to-front too

Edited October 25, 2018 by alastairq

[PatB]

I've never seen am A Series with a mechanical drive for a tacho, what model was that fitted too then?

 

 

Lucas devised the dynamo with a drive for the tach for the Frogeye when it came out!

I'm working from foggy memories of possibly inaccurate articles on an engine I wasn't that interested in then, read worryingly close to 40 years ago. My mention of a tacho drive may well have been wrong and based on incorrect assumptions . I do still seem to remember a lot of variations though.

[Southern Steve]

I'm working from foggy memories of possibly inaccurate articles on an engine I wasn't that interested in then, read worryingly close to 40 years ago. My mention of a tacho drive may well have been wrong and based on incorrect assumptions . I do still seem to remember a lot of variations though.

 

Oh there were many variations over the years from 803cc up to the last 1275cc A series and A+, high and low compression etc.

 

 

 

Never heard of a "mirror image" one though?  The way it rotates is governed by the dist drive shaft driven off the camshaft?

[2mmMark]

I wouldn't mind betting that these BMC cars being tested ended up as some of the quickest!

 

 

[unravelled]

Well, the pointsless system from simonbbc has been installed, and the engine seems to run more smoothly. I expect  to do some tweaking and a test drive when I get a chance.

I tried the strobe, but couldn't spot the timing marks. I'll clean up the notch and retry.

 

Checking with my "tuning Lucas ignition systems"  book, there are several 25D4 anticlockwise models. I haven't looked to see which engines they went with.

 

Thanks for the advice and comments

 

Dave

[alastairq]

For easy-to-spot timing marks, paint tippex onto the pulley.....ending at the timing notch. I hilite timing marks with the stuff, whether the marks are on the block, or on a pulley. A bit of black paint inthe notch itself helps as well.

 

On the mustang, I measured the diameter of the bottom pulley, then worked out how long a distance round the circumference various numbers of degrees would be[for example, how much circumference would 30 degrees equate to, etc] Then mark up with tippex to that point [or whatever full advance figure one is after.]

Personally, I look for as accurate a total advance figure that the maker specifies [need to know also, at what RPM timing is ''all in?''] Once that figure is achieved [by rotating the dizzy] then whatever the timing is at idle, is what it is.

 

Manufacturers try to give an optimum ignition timing figure at idle...but every engine has its own little foibles, and what suits one A series, [for example] may be a tad adrift on another.

 

Road testing on a local, known road over the same ground, tweaking the idle timing a bit back or forth, and feeling for how better or worse the engine pulls, is another method.....

But, always good to know the correct full advance is achieved [and when?]

[alastairq]

 

 

 

 

Never heard of a "mirror image" one though?  The way it rotates is governed by the dist drive shaft driven off the camshaft?

I did say it 'fitted' ,IE had the same fittings...but it definitely needed to rotate the other way [compared to an actual A series dizzy.] I do not have any information as to what other engines Lucas made these distributors for.....

[PatB]

I used to time my Beetle by trial and error, tweaking the dizzy round until i could just provoke it to pink by flooring the throttle in top on a hill on a hot day. Seemed to give both good performance (relatively speaking) and optimum fuel economy without eating plugs, valves or piston crowns.

[alastairq]

Such a shame that cannot be done on today's moderns?  

 

Things like, tightening brake adjustment for MoT, then backing that adjustment off a bit so a precious horsepower [or two?] isn't wasted?

The VW beetle speedo apparently confused many Americans......the little marks on the outside edge actually were not gear change points......but nobody explained that to customers, as a result, beetles in the USA seemed to hurtle about wherever they went........

Mine caught fire in Scotland..... a chum had a large [er]-type lady friend, who sat in the back seat, right side.......underneath the seat was the battery..whose 'cover' had almost disintegrated...thus, the large backside bounced the steel seat springs onto the battery terminals...heating up said springs beyond red heat......!

Several large thick newspapers cured that, and journey was resumed......bit of a stink, however....

[unravelled]

Well I took the van out for a short shopping run yesterday, and it certainly runs more smoothly. There is an occasional "catch"  in the engine note under some circumstances which will need looking into, but I know the engine is well off tune after all my tinkering. Of course the problem with A series engines is that they will run even if well off tune. I think they will drive, after a fashion, with a couple of plug leads swapped, so getting them right can be a long job.

 

Thanks

 

Dave