Thread: Flat spot caused by 3.5lt really a 3.9lt?!

So this is where the engine number sits... Factory 3.5L

23D00001

R.Rover/efi auto 8.13:1cr

1986 onwards


Does this mean we should be looking at timing around 10btdc?

Also, thanks for all the other guidance guys, I'll have a look at flapper spring tension and piston height through the plug hole when my Son and I are in the same place with the car again!

Originally Posted by ecodan

So this is where the engine number sits... Factory 3.5L

23D00001

R.Rover/efi auto 8.13:1cr

1986 onwards


Does this mean we should be looking at timing around 10btdc?

Also, thanks for all the other guidance guys, I'll have a look at flapper spring tension and piston height through the plug hole when my Son and I are in the same place with the car again!

G`day ,

this is only a suggestion , there`s no reason not to do as you`ll be advised .

Google how to set ignition timing with a vacuum gauge .

This takes into account the wear in all parts .

The numbers at the crank only mean something if the TTDC mark has been found and recorded , otherwise they are a guide .

I'd be running at least 10 degrees if not 12. One of my 3.5's had 15 degrees dialled into it by the PO and it still went fine unless it was a hot day under heavy load.

Okay set to 11degrees, definitely improved performance, so will adjust flapper next to increase fuel as still feels like it's starving under heavy acceleration.

Also will do stick stroke test through spark plug hole.

Probably unrelated, but a re-occurring problem is occasionally the car will crank till the battery is flat without catching. Majority of time it starts first crank, even when very cold.

Originally Posted by ecodan

Okay set to 11degrees, definitely improved performance, so will adjust flapper next to increase fuel as still feels like it's starving under heavy acceleration.

Also will do stick stroke test through spark plug hole.

Probably unrelated, but a re-occurring problem is occasionally the car will crank till the battery is flat without catching. Majority of time it starts first crank, even when very cold.

Next time it plays this game, check to see if you (a) have spark, and (b) there's enough bite in the spark. You mentioned 'new' distributor cap/rotor/leads... but I'm guessing you have'nt replaced the LUCAS ignition 'amplifier'

In the mean time, you could implement 'Gap Theory'. As an Industrial Sparky colleague of mine was wont to declare..

"Most electrical problems are caused by GAPS. Either a gap in the wires where there's Not supposed to be a GAP, or the lack of a GAP where there should be a GAP"

- Check every possible plug/connector in the Fuel Injection and IGN circuits, especially any 'Earths' to the body... - Land Rover has a well-earned reputation for designing & assembling dodgy "Earth Returns"

EDIT:- Vacuum gauges are not that pricey, and going on the Google articles, could be a worthwhile approach. http://www.ebay.com.au/itm/Mini-Dial...0AAOSw37tV8-Z-

Sage advice. Unfortunately untill the fault persists, i'm having trouble recreating it long enough to check the spark.
The Module sounds interesting... Shall investigate, though its not missing under load.

Meanwhile I'm going to change the fuel pump relay.

On other news, adjusting the flapper spring 5 notches anti-clockwise definitely gave more power through the flat spot. As did cleaning the contacts and strip.