dominicbeesley
Well-Known Member
- Posts
- 1,701
- Location
- Hebden Bridge, West Yorkshire
Firstly I'm not a retarded gibbon, but I must be a bit of a **** head for spending so much time on a Land Rover Petrol Engine. However, it's what I've got to play with and play with it I will...
It's advancing as per spec for a 45D I've drawn the graphs. I'm not arguing but all your saying is ooo baad but not saying _why_ (are landy pistons particularly soft?). From Wikipedia: (similar sentences in many of the the old engine and tuning books I've read) "Effects of engine knocking range from inconsequential to completely destructive." I know that running a motor bike at 16000rpm over advanced by a handfull of degrees at a race meeting will feck it up big time but a slight pinking at 2500 rpm that goes away at higher rpm is not the same...
I've already read the (self contradicting) hand books but the books are for timing a 8:1 or 7:1 head running on two or three star petrol with a carb that runs very rich so not a huge lot of help as I'm not running the engine like that. According to them I should be a few degrees ATDC in which case it would be quicker to walk.
The advance "curve" on a standard Lucas dissy is a pretty rough approximation of what is perfect. Two weights on quite rough pivots and held by two springs and a vacuum diaphram is never going to set the timing perfectly at all rpms and loads...thats why people spend time tuning. Again the mixture at different RPMs/loads makes a big difference. I've already swapped my dissy once cos the copy one I'd bought had crappy little weights in it and didn't advance properly and topped out at about 3000rpm. Like I said I've checked the dissy and its well within spec but spec is not necessarily _best_....
It's advancing as per spec for a 45D I've drawn the graphs. I'm not arguing but all your saying is ooo baad but not saying _why_ (are landy pistons particularly soft?). From Wikipedia: (similar sentences in many of the the old engine and tuning books I've read) "Effects of engine knocking range from inconsequential to completely destructive." I know that running a motor bike at 16000rpm over advanced by a handfull of degrees at a race meeting will feck it up big time but a slight pinking at 2500 rpm that goes away at higher rpm is not the same...
I've already read the (self contradicting) hand books but the books are for timing a 8:1 or 7:1 head running on two or three star petrol with a carb that runs very rich so not a huge lot of help as I'm not running the engine like that. According to them I should be a few degrees ATDC in which case it would be quicker to walk.
The advance "curve" on a standard Lucas dissy is a pretty rough approximation of what is perfect. Two weights on quite rough pivots and held by two springs and a vacuum diaphram is never going to set the timing perfectly at all rpms and loads...thats why people spend time tuning. Again the mixture at different RPMs/loads makes a big difference. I've already swapped my dissy once cos the copy one I'd bought had crappy little weights in it and didn't advance properly and topped out at about 3000rpm. Like I said I've checked the dissy and its well within spec but spec is not necessarily _best_....
