Pre cat timing

[chris212]

I need to set the timing on my 4.3 pre cat. I have found the tdc mark on the pulley with increments either side to 10 btdc and 10 after tdc . The bible says 34 degrees at 4000 rpm. I marked it with a protractor and I can get the marks to line up at tick over but I can't see it at 4000 rpm. Am I missing something? What should it be set to? Thanks

[blitzracing]

That will be 34' without vacuum- I suspect if you are revving it in neutral, it may have some extra vacuum advance added to it- so remove the vacuum pipe from the dizzy and and block it then try again, so you only have centrifugal advance.

[PH430]

34 degrees at 4000 rpm, is at tickover 1000rpm 11/12 degrees al with vacuüm off.

Good luck

[chris212]

Thanks for the answers . I cannot advance the dizzy enough (turn it clockwise) to get 34 degrees at 4k revs( vac pipe disconnected and blocked) . I am about 20 degrees out. I can get 12 degrees at tickover, which is what I've set it to and it now runs fine with no pinking. Just a bit concerned I cannot set it at 4k revs to spec. Is the vac advance faulty?

[carsy]

Twenty degrees out is a lot. Power and economy is going to be well down. The advance mechanism in the bottom of the dizzy can sieze and not work properly. I`d take the distributor out, strip it down and check that all the springs and weights in the base are free and working correctly.

[stevesprint]

Chris
To check the advance at 4,000 rpm you are best using a digital timing light with digital advance/retard function. When the timing light is set to flash with 34 degs advance it will flash at TDC when the engine advances the ignition by 34 degs.

I’d be surprised if your timing was out by 20 degs at 4,000 as you’ve got 12 degs at idle and especially as it drives ok, but still best to be safe than sorry.
Good Luck, Steve Sprint

[stevesprint]

PH430 said:

34 degrees at 4000 rpm, is at tickover 1000rpm 11/12 degrees al with vacuüm off.

Good luck

Is 11/12 degs for 95 or 97 ron fuel?
Cheers, Steve

[PH430]

stevesprint said:

PH430 said:

34 degrees at 4000 rpm, is at tickover 1000rpm 11/12 degrees al with vacuüm off.

Good luck

Is 11/12 degs for 95 or 97 ron fuel?
Cheers, Steve

It's Ron 98. Ron 95 will be 29 till 30 at 4000 rpm

[blitzracing]

Just in the process of purchasing one of these so less guess work. Strikes me as a bit of a bargain compared to other units out there, and I have I no doubt that Phil Ringwood and V8 Developments know what they are doing!


http://www.extraefi.co.uk/Misc_products.htm