You young fellas got it easy with metric. I was at school on Friday learning imperial and on Monday we were told that we were leaning only metric now, so I learned both. Really screwed me up as still use both depending on what I'm measuring.

Britain is just so awkward with that... The metric system is the way to measure things in jobs, school, etc. but you drive with mph and distances are given on miles and yards... And then you buy your screws and nuts mainly in imperial sizes for cars which are made fully metric...

I do prefer the US style... One or the other, not both. So everything is measured imperial... Probably the best way to avoid it all.

Oh, then comes a more awkward situation: tire sizes... Metric, Imperial and Per Cent.. What genius thought of that!? :D

How 'bout spark plugs? For as long as I can remember they've been Imperial on the hex and metric on the threads. Never heard a reason why.


Cheers
DD

I only know of metric plugs all round... Hex and thread!?

16mm is pretty close to 5/8", so we can all claim to be right here...

My B230F in my old 740 GL had 19 mm hex'

I'm sure the Empire would say that dimension was 3/4" (19.05mm)

Not so, Warrjon, it made you the Man you are! Without that rigorous mental training, you would not be doing the great stuff you are on that specially built engine and superb bodywork.
Greg

had to learn both... and use both
and convert back and forth as needed...
hp figures I like to use ft/lbs of torque as at 5252rpm they cross on the graph
and here in the US they advertise HP a lot...

Is this some oddity of IC engines in general? If so, why?

More convenient than kW and Nm that cross at 9549rpm

No, its anything that develops torque and movement (power).

example, torque - tighten a bolt to 200ft/lb and there is no power as the bolt is doing no work, ie its not rotating.

Electric motor that develops 200ft/lb of torque at 1440rpm would be making 55hp Tq*rpm/(5250 for HP/ft/lb and 9549 for kW/Nm).

The power whether in kW or HP is a measure of the work performed by the torque.

Warren, thanks! Science is always your friend :)

The saying 'horse power sells cars, torque wins races' is then a 'halfmyth', like the Toothfairy... We all know the fairy exists, but she doesn't want teeth :D

What is meant by torque wins races (originally said by Carol Shelby) is there are 2 ways of making power.

Increase torque What torque wins races means

Increase RPM like a Formula 1 engine

It is power (at the wheels, so gearing also plays a part) that makes a car accelerate which is the use of the torque, so if you increase torque across the RPM range power across the range will increase.

An example an F1 engine with 210ft/lb at 20,000rpm makes 800hp. A diesel truck with 1700ft/lb at 2500rpm also makes 800hp but there is no way an F1 engine will pull 80 tonne or a truck engine will do 0-100km/h in 2 seconds.

I like to use a comparisson from a modern car:

C30 2.0l vs. 2.0d

2.0l: 185 nm/145 hp
2.0d: 320 nm/136 hp

Both do 0-100 in 9.4s. The 2.0l will do 210 kmh the 2.0d will do 205 kmh

People who say torque wins races will say the diesel is superior than the petrol, as it has more torque. Numbers alone don't say anything... Luckily! ;)

in RACING
IT is all about the "RULES"
FI limited the cc to what...
so the engineers countered with uping the RPM

what ever RULEs the sanctioning body hits you with
you try to find the best way to have an edge over the competition

like if they made you use a 500cc engine Normally aspirated
you would try and turn 100,000 rpm to make up for the lack if cc's

now F1 and NASCAR both did a volume limit and the RPM in F1 went to the point where they (F1 sanctioning body) got scared and put a limit on the RPMs also... the forces at those high RPM if there was a failure could be really explosive.... and deadly

we on the street are ruled by $$$
what we want to get verses what we can and will pay
and soon in Germany what is allowed on the street...
all electric

Pulled plugs, ran a compression test, and changed the plugs (to NGK BKR6E) on my 1994 AJ6 4.0.

Plugs looked ehhh. Plug 4 was a little "wet", but overall, looks like nothing major to worry about.

Compression looked good: 187, 185, 182, 182, 187, 187.

Started it up, ran a circuit. Lot smoother, and no hesitating and stalling at low RPMs and change from D-R or R-D. I expect the MPG will go up too.

I'm happy.

Padre

SNG Barratt to the rescue
 

Just got in a Trigger Board kit and new Black Fan for my 83 project. Took two weeks as the board was a special order.

https://cimg9.ibsrv.net/gimg/www.jag...5daa3ab2da.jpg


new heart for my xjs is almost ready

(takes cover)

Okay, so i bought a 'few' things today...

- front oil seal and sleeve
- 2 woodruf keys
- two valve cover gaskets
- 24 valve cover screws
- 8 studs for front of valve covers with matching nuts and washers
- 2 stickers JAGUAR for valve covers
- 2 half moons for rear of valve covers
- new red valve cover cap (just for spares)
- crankcase ventilation housing with gasket, rubber cap, capsule and clamp incl. 2 new screws

And as I had to remove my old brittle flywheel bolt cover grommet, I looked to see if any place had one new... One shop, in the USa had one left. Otherwise they seem unavailable... Did I get the last one on the planet? I hope not!

But when all is here, I have some more work to do :) All due for January... 2017 will see a lot of work beimg done to my old Iron Lady.