46 replies to this topic

[minidave54]

I had set the timing at 12 degrees at 1000rpm and run the engine in, then put it in for a RR session. I only have a basic timing light so could not check the max advance at higher rpms. Guess I need to purchase a timing light with more advanced features.
The garage for the rr session has a very good reputation and came highly recommended

[GraemeC]

How are you measuring the 47 degrees max advance then?

I don't recall ever seeing a distributor that had 35 (17.5) degrees advance built in

[minidave54]

Those were the figures that came back from the RR session. Idle at 12 deg and max advance at 47deg.
The distributor is the one recommended by mini spares for the cam that i have

[nicklouse]

Sounds like the RR only did half a job and did not correct the advance curve.

 

it also sounds like they may not be too hot on A series engines.

[minidave54]

I have done some reading on setting up the max advance on the distributor.

From what i have read, if i buy a decent timing gun with advance feature i should be able to set the max advance myself.

 

Basically, engine at 4000 rpm to get distributor to max advance and set the timing at 34 deg, which i've read are the optimum figures.

Then take out for a test drive and listen for pinking under load and adjust if needed.

 

Have i read this right or does the distributor need replacing?

[sonscar]

the optimum figures are peculiar to only youre engine,others may be close but not optimum.Max advance is ok for max RPM but driveability is vastly improved with correct curve,this is what I thought rolling roads were paid to do.If the dissy is wildly incorrect hard starting and overheating is possible.Buying new parts is not the answer.Sorry.Steve..

[GraemeC]

You'll struggle to set it to 34 as that would mean you'd need 1ATDC at idle! (if the 47 is correct).

It sound like there is far too much advance in that dizzy or the figures quoted by the RR aren't quite right.

 

I'd very surprised if any RR left the advance so high it was causing pinking or damage, but you never know.

[minidave54]

Just a quick thought. Does it make a difference if the max advance was read with the vacuum connected.

 

Would this account for the high reading ?

[timmy850]

Yes. When checking the timing the vacuum should be disconnected.

 

My 850 distributor has a 17 degree advance cam - so a total of 34 degrees when timed to TDC

[minidave54]

Queried the distributor readings with mini spares and received this reply.

" The advance is set to start at 1000rpm & be all in at 20 degrees @ 4500rpm, obviously for the full advance you need to add the static timing but 47 degrees seems a bit high, it should be around 32 degrees."

 

I need to get this timing checked as it does sound like the max advance figure on the RR might have been done with the vacuum connected

[nicklouse]

Queried the distributor readings with mini spares and received this reply.

" The advance is set to start at 1000rpm & be all in at 20 degrees @ 4500rpm, obviously for the full advance you need to add the static timing but 47 degrees seems a bit high, it should be around 32 degrees."

 

I need to get this timing checked as it does sound like the max advance figure on the RR might have been done with the vacuum connected

But the vac only works with the throttle closed.  The vac has no affect on max advance.

[GraemeC]

Queried the distributor readings with mini spares and received this reply.

" The advance is set to start at 1000rpm & be all in at 20 degrees @ 4500rpm, obviously for the full advance you need to add the static timing but 47 degrees seems a bit high, it should be around 32 degrees."

 

I need to get this timing checked as it does sound like the max advance figure on the RR might have been done with the vacuum connected

 

So they agree with the 12 degrees at tickover (no vac connected) and in theory are saying their dizzy shouldn't then be able to make 47 from there.

Definitely worth checking what you have - I think the 47 is a bum steer.

[minidave54]

As always a great and friendly forum. Thanks all for the help and advice.

 

I will get a better timing gun which can read the max advance and see what i have. Something is not right with the figures.

 

cheers

Dave

[minidave54]

I have been away for a while, but have managed to get myself a new timing gun. Accuspark SP800 with advanced timing feature.

 

Can't say i'm impressed with it. The RPM setting is fluctuating and inaccurate. Car tacho 1000rpm timing gun anywhere between 1200 and 1800rpm.

The timing light which did initially work has now stopped.

I have contacted Accuspark with these issues and am waiting on a reply.

 

Has anybody else had similar problems with this timing light ?

[GraemeC]

You’ll probably find the gun is more accurate than the tacho.

Dont think I’ve known an a series that gives a steady reading on a digital timing gun.