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MG MGB GT V8 Factory Originals Technical - Ignition settings, factory V8

Sorry for asking so many questions, but I'm struggling to find all the engine data for my car!

1) Can anyone recommend a book that includes all the service information for the V8?

2) After searching the archives, I've found the following:
Timing: 8 deg btdc @1000 rpm, 26-30 deg btdc @ 2000 rpm (vacuum advance disconnected).

Points gap: 15 thou.

Could someone tell me which plugs I should be using, and what gap I should set them to? And does anyone know what the dwell angle should be (I've been given a meter, and I'd like to check for my peace of mind)?

3) The tappets sound fine at the moment. However, is there any adjustment on them? If so, what is the setting?

4) Really stupid question this one: is no. 1 cylinder the front left, as you stand in front of the car looking under the bonnet?

I'd really like to check these settings, to make sure they're not causing any overheating. My car still runs a little warm in traffic: I'm not unduly worried, but I'd like to make sure it's set up as well as possible.

Many thanks, and sorry again for the glut of questions!
Darren Ainsworth

Darren
Moss and the club offer the original V8 handbook -come back if you need more

Roger
RMW

Wow, does the handbook actually contain all that information? I'll give Moss a call, thanks for the tip!
Darren Ainsworth

Darren,

1) You can find the specs here too - although I don’t know how accurate they are. http://www.mgcars.org.uk/MGB/mgbgtv8spec.html
2) Spark plugs: Champion L92YC or equivalent. Gap: 0.035in
3) Hydraulic cam followers so no tappets to adjust.
4) Number 1 cylinder is the front left, with front being the front and left being the left of the car (as you sit in the driver’s seat). Nearest you on the right if you stand in front of the car looking under the bonnet.

Geoff
Geoff King

Dwell should be 26 to 28 degrees. This can be adjusted with the engine running which is useful (although the points have got to be one of the most accessibile on any car in the world), but in my experience whilst turning the hex bar one way alters the dwell in one direction, turning it the other way doesn't immediately, you have to wiggle things around to get them to seat properly. If you don't do that the dwell will change whilst driving. The upshot is that if it is in the range 26 to 28 don't be tempted to fiddle with it to get it to 27, you won't gain anything.

Basic timing is as you quote, with full curve info at http://www.mgb-stuff.org.uk/wn_ignitionframe.htm, click on 'Distributor Curves', then scroll down to the bottom for the V8.

Cooling can be a big area. When everything is correct it shouldn't be a problem, but there are a lot of areas which can all contribute to running hot. Not long after having mine I was stuck in traffic on a 90F/32C degree day and the needle was in the red. Nothing happened except the idle was a little rough, so I pulled out the choke a little bit to get a bit of fast idle, which probably added to the temp but at least it maintained oil pressure. Shortly after that I replaced the radiator with a 25% uprated one which looks identical other than an extra row of tubes, but it didn't make that much difference. The biggest difference came from making sure the electrical connections to the fans were all sound, and uprating them to include a local ground to the bonnet shut platform for each fan and a direct connection from the spare output spade on the alternator to a spare input spade on the fan relay (may not be present on the original relay). This made a massive difference to fan speed, since then I have run it under test in ambients of 105F/40C degrees and the needle only got 1/3rds of the way from N to the red, albeit with the fans running permanantly. It still runs a little above N on motorways in traffic in ambients of high 20sC and above, but that is nothing to worry about. I have replaced the Otter fan switch with an SU Burlen as the Otter was getting erratic, the Burlen cuts in at a lower temp which is no bad thing, but unfortunately it doesn't cut out again until the needle is nearly back down to N, which means that sometimes the fans are running for a very long time. I also had a problem where the thermostat bypass tube inside the inlet manifold got blocked which gave a spell of vomiting coolant out of the overflow, which is something to watch out for.

Basically, if it isn't losing coolant or steaming, it isn't overheating, no matter what the temp gauge says.

Enjoy.
Paul Hunt

This isn't for the factory V8 but if you check out this topic:

BOP/Rover firing order diagram

and then go to this link:

http://www.zaks.com/mgb/


it may have some of the information you are seeking.

Michael S. Domanowski

Many thanks for the help, and the links. I've adjusted the timing now, for some reason a previous owner had marked the crank pulley at 2 deg atdc: it's running much better now that it's set correctly.

The temperature is more stable now: it runs at just above 'N' on the motorway, and didn't boil over in a 20 minute jam this morning (although it was creeping towards the red). However, as soon as I was moving again, the temperature fell quite quickly back to normal, so I guess I've now got some confidence in the cooling system.

I'll only worry if it boils in future!

Darren Ainsworth

This thread was discussed between 30/07/2004 and 02/08/2004

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