GearBox Oil

The Baldwin equivalent is a B2-HPG.

I always thought that my 289 was unusual (perhaps it is). With a 3.07:1 diff and an LT77 gearbox it is happiest in 3rd at 3omph. Compared to modern cars it always seems a bit counter intuitive. When we originally built it we used a 3.7:1 diff. (MGC automatic I think) which was fine but rendered 1st gear useless. When the diff became very noisy I swapped it for the 3.07 which is a great cruising set up.

I know that lots of Dax and the like 30 years ago with big Chevrolet engines were running 2.88 differentials

David

It's not about lubrication of the engine, it's about cleaning up the swarf - quality of oil is irrelevant.  When you run in a newly-built engine, you are putting together a lot of components that have never been together before, and the first few hundred miles are really a continuation of the machining processes.  Hence the term 'running in', and hence the need for frequent filter changes.  Most engine builders I know follow best practice and change the filter at 100 miles from first start-up, cut the old one open for inspection and send a sample of used oil to a lab for analysis.  Initial analysis can be shocking, but is normal.  If you cut open a 100-mile 'new' filter you will be surprised at what (should) gets trapped in it.  The same goes for axles and gearboxes - my T10's had three oil changes since new, and will get another one in the next couple of weeks when (if) I get around to it.  It's what the builder told me to do anyway, and for the amount that thing cost I'm taking no risks.

I have to admit to not usually sending samples to labs but know I should.  It's also interesting to cut open a variety of filters to see how they are structured.  They are very different, with some very well made and others apalling.  Comparison test seem to show Fram not scoring too well on the whole, whereas Purolator are excellent as are Motorcraft (they are pretty much the same).  There was an excellent comparison on t'net a while back, but I can't find it - here's one that may be of interest:

http://www.austincc.edu/wkibbe/oilfilterstudy.htm

- but it's a bit limited and I don't know how old it is.

The 2.88 Jag diff is far and away the commonest, which makes it easy to source for most builders - pretty much every XJS and larger saloon had this ratio as the pressure was applied to show good mileage figures.  You won't find anyone running at Goodwood with one though - but that's not what we're about anyway!

A 2.88 diff is probably too tall for a small block, but for a big block, it's no problem at all. Original 427 Race & 427 S/C Cobras generally ran 3.54:1 diffs, but as you rightly point out, we're not racing our cars.

Paul

It is interesting that in the conclusions section of the article that you posted a link to Roger, the author believes the Motorcraft filter element is too tightly packed and could restrict oil flow.

Paul

Posted by: Paul Blore

A 2.88 diff is probably too tall for a small block, but for a big block, it's no problem at all. Original 427 Race & 427 S/C Cobras generally ran 3.54:1 diffs, but as you rightly point out, we're not racing our cars.

Paul

Block size will make no difference to how one would need to drive in an urban environment, assuming both cars have similar gearbox ratios with a 2.88 axle ratio.   Below 2,000 to 2,500 rpm the motor will not be running on the mains circuits or with the iginiton mechanical advance mostly in, so you will be relying on transition porting and an empirical distributor curve to keep the engine healthy.  No matter how much torque the engine can produce, petrol engines do not like being run for extended periods at low revs - that's where the real wear takes place.  Factory 427s had 3.31:1 ratios, as far as I'm aware - I run a 3.50 axle behind the Mustang's 393. Keep those revs up, chaps!

As someone who is shortly to experience the joys of Cobra motoring I must say I am becoming very nervous at the prospect of even starting up the engine let alone driving the car judging by all the comments being made concerning oils, filters and debris.  I thought American built V8s were pretty much bullet proof, just like Russian tanks. How is a man to proceed I ask myself.  My Hawk Cobra has a stock rebuilt 1966 Ford 289 mated to a new Tremec T5 World Class gearbox driving an MGB V8 rear axle. I would expect this combination to give me at least 100,00 miles before needing any attention whatsoever(well possibly not the axle). By that time I will be 100 years old.   Am I missing something here?

On Sunday I was out in the Healey for the St Georges Day run, covered around 150 miles in hot weather, oil pressure 50 psi and temperature constant at 175 deg F. No electric fan.  Engine, gearbox and back axle just as I bought it in 1972, never been touched. Clock now reading 95 thousand miles. Oil changed every 5 years whether it needed it or not.(Duckhams 20/50)

I did change oil and filter on the Cobra after Cam break in and will probably change again at around 3oo miles (i.e. after a good long run).

Thereafter an oil/filter change at a further 1000 miles would seem sensible. Any further advice gladly received.

I am expecting The V5 to land on my doormat around the 1st of May!  First big trip will be to Le Mans I guess.

Sounds about right to me, Byron!  Only sensible with a new engine.  Your Healey will be bone stock (and all the better for it, I sometimes miss the old 'C' series truck engine).  What you do with your Cobra rather depends on how the motor was built, as it's not likely to be as 'factory' as your Healey motor.  But there's no reason a cast-iron pushrod engine shouldn't just go on and on, really.

Posted by: Roger King

  Factory 427s had 3.31:1 ratios, as far as I'm aware

I'm pretty sure the 427 Road cars also ran with 3.54:1 diffs.

I'm more inclined towards your perspective Byron. These weren't temperamental or fragile engines in period, and there's no reason to believe that they have become more so with passing time.

Paul

I am so looking forward to seeing a 100-yr-old Byron driving a Cobra.

That's always assuming I last that long.