The V8 Owners Forum -

Hi all, just a quick query about trying to get the timing right on my ex rover 3500 engine now fitted in a capri. its got an accuspark ingnition amp fitted in the distributor. Is there any way of double-checking the pulse from this lines up with the spark at the critical moment and do I need to?

The basic problem is that it idles beautifully, then when you rev it it looses power, pops and spits and doesn't pull under load and misfires popping and banging. Ive changed the plugs and leads, its not the fuel and I believe the carbs to be set up/running ok and have set the mixture ok.

Ive got a new coil on the way but The only thing I can think is it could be a timing issue. It does it whether the vacuum advance unit is operating or has had the tube pulled off and blocked up ? So I'm wondering if I need to try and change the position of the hall effect senor on the plate. Ive tried advancing and retarding the static timing with little joy. any suggestions welcome!?

cheers Barry

Normally you would not bother to try to work out if the pickup is getting triggered at the right time, really just by checking the high tension at the HT lead you are checking the rest of the system anyway. In order to check the timing you just need a strobe but really you should check that the damper wheel pointer lines up with the TDC mark on the damper wheel when piston number one is exactly at TDC.

As the standard damper wheel does not have many useful marks other than TDC you are better off with dial back timing gun because you can just use the TDC mark.

I pressume that you are using SU carbs, these are not really my thing but I think that the vac advance with this sort of setup is non-timed, i.e. it is applied at tickover. This means that you would probably set the timing up at around 0-4 degrees BTDC with the vac tube removed and the engine ticking over. You can then fit the vac tube and note that timing at tickover will probably go to around 12-16 degrees or something like that. You can test the all-in timing figure with the vac tube removed, rev the engine until the bob weights add no more advance, the timing will be around 36 degrees. It should be all in by 3000 RPM.

I actually suspect that you have a fueling issue, assuming that your timing is not miles out then a lean mixture will cause the sort of problems that you have described. Of course this is just a hunch really!

thanks sidecar. By a process of deduction I reckon you're probably right, if i've been altering the timing and nothings changed its got to be fuel/air mixture or something breaking down under load. time to screw in those jet mixtures! cheers for your help B.