Timing settings X -flow 1700

[John Whyman]

Please forgive my ignorance but new to this one. My Caterham manual for my 1989 registered 1700 s/sprint says my BTDC timing should be 10 degrees. Thinking that the vehicle could have been a 1990 model, and having been told by them that I could use unleaded for a few tanks and then leaded fuel, I queried the timing with Caterham, who said it should be 14 BTDC.

 

Timing marks only go as far as 12 degrees, so how does one set it with a timing light, guess work?? or is there some useful dodge to get it right?

[Casbar]

Use a variable time gun. If your going to buy one, make sure its a decent one. 14 degs sounds about right, but depends on the type of distributor you have fitted. You should also checks the timing when the engine gives you full advance, over 4500 revs I believe, but check with Roger King first.

 

Suggest you give Roger King a bell, he'll provide all the guidance you need.

[stevefoster]

At tick over it's not really relevant. You want lots of advance at high revs. 34 degrees rings a bell on my 155bhp RK 1700 XF as maximum advance at something like 5000rpm.

Roger K is the man to ask.

[Roger King]

1989 is a tricky one, because it was about then that Caterham changed to their unleaded distributor.

 

As a general rule, if you have a Bosch distributor this is a leaded one and should be timed in at 10 degrees at tickover. If you have a Lucas distributor this will probably be the unleaded and should be set at 14 degrees at tickover. This assumes that no one has changed anything from factory spec.

 

Casbar's advice about the variable timing gun is correct. So too is Steve Foster's advice about setting timing at full advance being better, but unless you are fully familiar with the engine spec it would be safer to stick to the tickover settings. For example, if you have an unleaded distributor and set the timing to 34 degrees at full advance, you stand a very good chance of suffering severe detonation damage at lower revs; the leaded distributor on the other hand would probably be correct on that setting.

[John Whyman]

Thanyou all and especially RK, who confirms my suspicion about change over. The distributor is Bosch with Lumenition 'magic eye',(I think this is a home conversion) So will set up at 10 degrees and stick to the leaded stuff.