It’s all in the timing

When you’re sat next to your little girl’s bed in hospital, it’s 4am, you haven’t slept in days and there’s no more Jammie Dodgers left on the nurse’s station – the last thing you want is the banality of 24 hour telly. At times like these, you want distraction, you want warm comforting words, you want to know that the simple things in life work and that they can be explained … you want Des Hamill 

One subject that’s close to his heart is his passionate belief that in anything other than a run of the mill, bog standard production engine, ignition advance should be “all in” by 3650 RPM. It’s hardly the makings of an election manifesto, I’ll grant you, but if I learned one thing from the book it was that.

Now I’ve had many an hour to ponder what I might do with my car over the last few years, read many a blog article, absent-mindedly added a million things to my eBay watch list (maybe even bid on one or two ) and drifted off to sleep making yet another mental list. One of those lists concerns giving the engine a bit more poke -but that’s all it needs is “poke”. Don’t get me wrong, resto threads with triple-turbo’d YB screamers, or V8-bellied drag monsters with rear tyres wider than my sofa are fascinating, it’s just not what I’m after for my car … it just needs a bit more poke 

But like that advertising line from the other year went – poke is nothing without control. So, with that in mind, today’s task was to understand the ignition advance curve that I’ve currently got. Call it idle curiosity, but in an awful lot of googling I don’t think I’ve seen anything about “standard” curves on the Bosch Pinto distributor, so I thought I’d find out. Now a long time back the only way I had to check the timing was an old Gunson light that required you to make your own degree markings on the pulley, barely illuminated them anyway when you did and occasionally zapped you if your hand went too close to the unshielded wire on no. 1 spark plug. Time for a change then. I knew I wanted a timing light with;

  • inductive pickup
  • a really bright bulb
  • the ability to dial in advance so I only had to make sure TDC was clearly marked
  • a rev counter, because funnily enough, when I’ve got my head under the bonnet I can’t see the one on the dash

Fancy Snap-On ones come up frequently on eBay, but they usually end up going for fancy prices. Of all the rest, I plumped for an Accuspark SP8000 as it seemed to be fairly well reviewed and was less than fifty quid.

This isn’t a big review; it plugs in, it flashes, it reads revs, it works. Yeah, it feels a bit plasticky but that’s cause it’s plastic. Some folks said the buttons can be a little fiddly to use when you’re trying to flip from advance to RPM and pull the trigger whilst turning the dizzy – they must have stubby little fingers as I found it alright. Bang on the money, really 

So now I’ve got the timing light, but I’m not Mr Tickle, so I was trying to work out how I could reach the throttle, hold it at a 500 rpm increment for a few seconds to let it settle, whilst playing a merry dance with the buttons on the gun to flip between revs and advance to work out what the dizzy was putting in at each point. Burtons probably sell a chrome thingy to do the job, but I just bent a length of rod to hook into the bracket on the carb’s throttle spindle .. and ended up with something that give’s incredibly fine control yet is easy to hold. You can watch the revs on the gun, when it hits your next rpm increment you listen to the engine note as it settles, flip the display on the gun over to advance and use the buttons to move it forward until the timing mark on the pulley lines up with the guide. It actually takes longer to write about it here than to do it (and it’s impossible to hold the throttle, the gun and take a picture) 

When you’ve been through the rev range, you end up learning that the standard Bosch distributor on a 2.0 Pinto has an ignition advance range of 24 degrees, with a curve that looks (subject to me getting it wrong) like this;

Well isn’t that fascinating… 

Apologies if you read all that and thought “huh, where’s the ending?” – think of it like those bloody Lord Of The Rings movies; there’ll be more soon … 

Group4_Mark2: Great Job, Glad to see you back on the forum. I hope that your little girl is feeling better.

I take it that you have the vacuum advance disconnected while doing this test?

Me: Yeah, she’s doing fine now thanks – all that hospital nonsense was a few short years ago; occupied every single waking hour at the time but now thankfully it’s largely forgotten. 

Vac advance was indeed disconnected and plugged up, just like it should be. Never plugged the line beforehand … simply didn’t cross my mind until I read one day that it would be destroying the vacuum in the inlet, I was only ever thinking about having it unplugged so it didn’t engage the vac advance on the distributor 

Idle curiosity has me wondering if there’s a way to measure the curve of the vac advance, but I can’t think of an easy way to test it at the moment