Dizzy drive gear.
Discussion
Hi,
I have a 35D distributor from a Serp’ engine ('95 Chim'). Is it possible to change the drive gear to suit a Pre-Serp’ engine so I can keep it as a spare for my '92 Griff'?
Seen this on the web which prompted me to ask if the only difference between the Dizzy's is the long drive gear to drive the oil pump.
https://www.ebay.co.uk/itm/Drive-Gear-Rover-V8-Eng...
Cheers
I have a 35D distributor from a Serp’ engine ('95 Chim'). Is it possible to change the drive gear to suit a Pre-Serp’ engine so I can keep it as a spare for my '92 Griff'?
Seen this on the web which prompted me to ask if the only difference between the Dizzy's is the long drive gear to drive the oil pump.
https://www.ebay.co.uk/itm/Drive-Gear-Rover-V8-Eng...
Cheers
It may be possible to change it but you would need to confirm it has the same tooth count.
But, internally it may have different ignition timing as in the limit stops for the fly weights may be different.
Question...If you believe a dizzy is a 'must have' spare what else are you going to fill the boot with?
Steve
But, internally it may have different ignition timing as in the limit stops for the fly weights may be different.
Question...If you believe a dizzy is a 'must have' spare what else are you going to fill the boot with?
Steve
The dizzy was made redundant when the Chim' serp' lump, went MS, then when the Chim' moved out I kept the dizzy just in case it would be a spare for the pre-serp' but forgot the drive for the oil pumps is different on the two engines.
So if it can't be altered to suit by changing the drive gear, then I might as well out it, especially if the internals don't match.
The boot spares I carry are only the basics I can fit in the original TVR bag, nothing big and heavy, I'm wondering why I even keep a jack and wheel brace as I don't carry a spare wheel. I trust my fleet breakdown provider will get me out of trouble if I get stranded.
Lance
So if it can't be altered to suit by changing the drive gear, then I might as well out it, especially if the internals don't match.
The boot spares I carry are only the basics I can fit in the original TVR bag, nothing big and heavy, I'm wondering why I even keep a jack and wheel brace as I don't carry a spare wheel. I trust my fleet breakdown provider will get me out of trouble if I get stranded.
Lance
As engine speed increases you need to fire the spark earlier so that the burn happens at the optimum time.
To achieve this the dizzy has fly weights in the base which fly outwards as the engine speed increases. As they move out they change the ignition timing. Typically your engine will be about 12 degrees advance at idle and 38 at high revs.
The curve is all about the rate at which the timing changes.This is achieved with springs fitted to the weights to try and prevent them flying out and the curve is controlled by having different tension in the springs. You may have heard the term 'all in at 3500 RPM'. This refers to the point in the rev band that the timing hits a limit stop.
A mapped ECU can achieve a much better control of the curve than some worn-out stretched springs.
So this is why I suggested that the curve of your spare dizzy may not suit your engine.
Steve
To achieve this the dizzy has fly weights in the base which fly outwards as the engine speed increases. As they move out they change the ignition timing. Typically your engine will be about 12 degrees advance at idle and 38 at high revs.
The curve is all about the rate at which the timing changes.This is achieved with springs fitted to the weights to try and prevent them flying out and the curve is controlled by having different tension in the springs. You may have heard the term 'all in at 3500 RPM'. This refers to the point in the rev band that the timing hits a limit stop.
A mapped ECU can achieve a much better control of the curve than some worn-out stretched springs.
So this is why I suggested that the curve of your spare dizzy may not suit your engine.
Steve
Steve,
Thanks for that.
It's in good mechanical condition, but painted red like the remainder of the Chim' engine was by the PO, so I'll hang on to it for the time being as at least I know with the correct drive gear I can use it in the pre-serp, with the bob-weight springs swapped of course.
Cheers
Lance
Thanks for that.
It's in good mechanical condition, but painted red like the remainder of the Chim' engine was by the PO, so I'll hang on to it for the time being as at least I know with the correct drive gear I can use it in the pre-serp, with the bob-weight springs swapped of course.
Cheers
Lance
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