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35DLM8 mechanical advance
Posted: Thu Dec 07, 2006 11:16 am
by landy_v8
Hi Guys,
When replacing my points dizzy with a 35DLM8 I noticed it had a sleeve over the stop for the bob weights. I assume this effectivley reduces the max mechanical advance a bit. Would there be any benefit from removing the sleeve (It comes off easily enough) or should I leave it alone?
On a 3.5L with 8.35:1 CR and SU Carbs what should be the max advance and at what RPM?
Cheers
Jon
Posted: Thu Dec 07, 2006 5:47 pm
by badger
Leave the sleeve fitted to restrict the total advance and set the timing at idle (no vacuum) to about 10 degrees BTDC - this will give good pickup at low rpm's with the low compression engine without running the risk of high-speed pinking.
Re: 35DLM8 mechanical advance
Posted: Fri Dec 15, 2006 8:50 pm
by Paul B
landy_v8 wrote:Hi Guys,
When replacing my points dizzy with a 35DLM8 I noticed it had a sleeve over the stop for the bob weights. I assume this effectivley reduces the max mechanical advance a bit. Would there be any benefit from removing the sleeve (It comes off easily enough) or should I leave it alone?
On a 3.5L with 8.35:1 CR and SU Carbs what should be the max advance and at what RPM?
Cheers
Jon
I have heard several times that Rover run notoriously feeble mechanical advance, and usually need some mods to get the full power out of them, but, it is all stuff i have heard/read and I have no dyno figures to back it up. here's an article you might want to read.
http://www.seight.com/ignition.html
I could not get more than about 18 degrees of mech advance on my SD1 motor, until I fitted some softer springs from Real Steel and also ground a little off the bob-weight stop, then I could get 30 degrees full mech advance (and still have 6 degrees at idle, as recommended in the Rover spec).
You might find yours is restricted even further as with that low C/R it is probably designed to run safely on rubbish quality petrol in some third world country.
Posted: Mon Dec 18, 2006 10:01 am
by landy_v8
Thanks for the replies.
You might find yours is restricted even further as with that low C/R it is probably designed to run safely on rubbish quality petrol in some third world country.
The engine is from a 101 Land Rover Gun Tractor so was designed to run on crap fuel. The dizzy is from an EFI Range Rover that I think had a CR of 9.35:1 so not sure what advance it should have.
Is there a way of measuring the advance a dizzy will give?
Cheers
jon
Posted: Mon Dec 18, 2006 4:45 pm
by Paul B
landy_v8 wrote:Thanks for the replies.
You might find yours is restricted even further as with that low C/R it is probably designed to run safely on rubbish quality petrol in some third world country.
The engine is from a 101 Land Rover Gun Tractor so was designed to run on crap fuel. The dizzy is from an EFI Range Rover that I think had a CR of 9.35:1 so not sure what advance it should have.
Is there a way of measuring the advance a dizzy will give?
Cheers
jon
I'd imagine you could set it up on the motor, strobe it at idle, (say 6 degrees btdc at 600rpm) then wind it up to 4000rpm and strobe it again. I know my '84 SD1 dizzy was giving barely 22 degrees like that. Now I have modded it it gets some 36 or thereabouts.