The V8 Owners Forum -

sidecar wrote:
The dizzys that you've looked at could easily be different to the ones that I've worked on and therefore may have had less mechanical advance.

Cheers,

Pete

I actually raised the issue on here a hundred years ago, or so it seems now, and was given this link http://www.seight.com/ignition.html that explained it quite neatly. I also posted it earlier this thread, but the jist of it is:

The standard SD1 distributor has bob weights that are supposed to give 26 degrees of mechanical advance but they only give 22 degrees. The 3.5 litre engine needs 34 degrees of total timing at wide open throttle and this should be all in by 3000-3500rpm. The standard advance springs do not allow maximum advance until about 4000-5000rpm. You can replace the springs in the distributor with weaker ones (available from Real Steel among others) to improve this. Using this timing will result in about 12 degrees at idle which works very well with a fast road cam. It is enough to get the idle nice and smooth but not so much as to make starting difficult.

I believe the stock setting for static, according to the Rover book of words, is about 6 degrees at low idle, which, when you add the 22 degrees mech advance, gives naff all near what you really want. Obviously, if you start with 12 degrees, you are doing a lot better, but it all seems very strange to me that Rover would make what appears to be a mass production boo boo in the potential power stakes.

I actually found advancing the static much more than Rover quote made starting harder. it would churn for ages before catching some days.

I fitted the springs and ground some steel off, and I now get a full 36 degrees advance at about 3000rpm plus a nice low advance for start-up.

Paul B wrote:

sidecar wrote:
The dizzys that you've looked at could easily be different to the ones that I've worked on and therefore may have had less mechanical advance.

Cheers,

Pete

I actually raised the issue on here a hundred years ago, or so it seems now, and was given this link http://www.seight.com/ignition.html that explained it quite neatly. I also posted it earlier this thread, but the jist of it is:

The standard SD1 distributor has bob weights that are supposed to give 26 degrees of mechanical advance but they only give 22 degrees. The 3.5 litre engine needs 34 degrees of total timing at wide open throttle and this should be all in by 3000-3500rpm. The standard advance springs do not allow maximum advance until about 4000-5000rpm. You can replace the springs in the distributor with weaker ones (available from Real Steel among others) to improve this. Using this timing will result in about 12 degrees at idle which works very well with a fast road cam. It is enough to get the idle nice and smooth but not so much as to make starting difficult.

I believe the stock setting for static, according to the Rover book of words, is about 6 degrees at low idle, which, when you add the 22 degrees mech advance, gives naff all near what you really want. Obviously, if you start with 12 degrees, you are doing a lot better, but it all seems very strange to me that Rover would make what appears to be a mass production boo boo in the potential power stakes.

I actually found advancing the static much more than Rover quote made starting harder. it would churn for ages before catching some days.

I fitted the springs and ground some steel off, and I now get a full 36 degrees advance at about 3000rpm plus a nice low advance for start-up.

Its all good stuff!

Its interesting that your motor did not like much static advance, my tickover increases each time I add more static advance which would indicate to me that the motor "likes" what I'm doing. I'm running 14 degrees static at the moment.

I guess the static compression ratio and the cam could make a big difference to the setup required.

I got the idea of more advance from Des Hammills book, he reckoned that Rover specified so a low value because they have to set the motors up to run on piss poor fuel and/or wallies that load the motor up rather than changing down a gear.

Cheers,

Pete

Been having a read of this thread and it has really helped my own problems out .
I am using a mallory unilite which came with a two stage advance curve . I'd get pinking at 2,000 rpm whenever i tried to run a static advance above 8 deg . The car was as dull as dishwater untill i hit 3000 rpm this way .
After reading this thread and checking the links i've now gone for a straight line advance curve and am on an indicated 15 deg static . What a car she now is - nice crisp power everywhere .
Good thread , thanks , gordon .

Rage Rover wrote:Been having a read of this thread and it has really helped my own problems out .
I am using a mallory unilite which came with a two stage advance curve . I'd get pinking at 2,000 rpm whenever i tried to run a static advance above 8 deg . The car was as dull as dishwater untill i hit 3000 rpm this way .
After reading this thread and checking the links i've now gone for a straight line advance curve and am on an indicated 15 deg static . What a car she now is - nice crisp power everywhere .
Good thread , thanks , gordon .

I'm glad that the info has helped you.

I've now junked my 3.5 lump and have built a warm to hotish 4.6 so I'll have to start from scratch! I was going to go for 12 static 28 total all in around 3-3.5k rpm.

Pete