There was a post here some while ago about doing this using springs from a Moroso kit, I started dismantling my p6 distributor and found my advance weights aren't the same as the poster's distributor so I'm wondering if I should still use a silver and a copper spring?
The advance stop plate (is this what its called?) is stamped 13° so with 10° static I need to alter the stop to give around 9° to end up with 28° total advance - does this sound about right?
Ideally this job needs doing when the engine is running but its a new build that I haven't had running yet so I want it to start quickly and run to get the new cam & followers bedded in.
Recurving a 3.5 RV8 distributor for a 4.6
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It was probably one of my posts that you are refering to. I think that you will have to suck it and see with regards to whether the springs will be right.
The other thing (and this is going to annoy you) but the 13 stamped on the dizzy is the degrees of advance it can offer at the dizzy not the crank! This is mental but its true. Your dizzy in its current state has 26 degrees of advance at the crank.
The other thing (and this is going to annoy you) but the 13 stamped on the dizzy is the degrees of advance it can offer at the dizzy not the crank! This is mental but its true. Your dizzy in its current state has 26 degrees of advance at the crank.
I think ratwing understands that the dizzy and engine advance is divided by 2.
Hence he said 9 degrees doubled plus static 10 degrees static equals 28 degrees.
He probably would be better with 14 degrees static and the dizzy stopped at 7 degrees. (ie 14 degrees crank advance)
Hence he said 9 degrees doubled plus static 10 degrees static equals 28 degrees.
He probably would be better with 14 degrees static and the dizzy stopped at 7 degrees. (ie 14 degrees crank advance)
1950 A40 Devon Hotrod with 5.0 twin turbo RV8.
EDIS8 wasted spark, Holley Injection.
Been as far as the Moon and back in 57 years of driving. Same Car, 5 engine upgrades !!!
EDIS8 wasted spark, Holley Injection.
Been as far as the Moon and back in 57 years of driving. Same Car, 5 engine upgrades !!!
Oh, that will teach me to read things properly!
Yep, I think that somewhere between 28 and 30 is what you want to be running as total advance on a 4.6 at WOT BUT this does depend on all the usual things, with the CR being the main one.
14 degrees at idle is OK but all of this depends on whether you are going to run a vac advance system. If an Eddy carb is being used on the timed port then this setup does not work too well.
I'm actually starting to think that running a vac system on the non-timed port might be better. Then with this setup aim for around 18-20 degrees at idle. The all in with no vac (at WOT) would still need to be 28-30, all in with the throttle just cracked open could be much more and this would be OK.
One day I might try all of this as I run a programmable MSD. Figures off the top of my head would be something like:-
20 at idle with 14 being made up by what the vac system is adding, the other 6 being the static timing figure.
Then when the throttle is booted from tickover the timing would back off to 6 but would start to climb as the revs rise. Assuming that the throttle is floored all the way to the redline this figure would climb due to the bob weights to 30 degrees all in at 2750-3000 RPM. Then if the throttle was backed off the extra 14 degrees that the vac system can provide would kick in giving 44 degrees in total.
The reason that I think that the timing should actually back off it that at just above idle or low RPM with the throttle just cracked is that the VE is very poor so the charge needs to be lit much earlier. BUT at low RPM with your foot on the floor the VE is very high so the peak cylinder pressure BEFORE the charge is lit is high, this means that there will be a rapid burn rate, this means that less advance is actually required. Also as the RPM is low there is more time for the burn to complete before the piston rushes back down the bore on the power stroke.
Having said all that I can't quite be arsed to try it out! (I did notice that an old mini I was working on it used the non-timed port, and I reckon it was for the reasons that I have described above).
Yep, I think that somewhere between 28 and 30 is what you want to be running as total advance on a 4.6 at WOT BUT this does depend on all the usual things, with the CR being the main one.
14 degrees at idle is OK but all of this depends on whether you are going to run a vac advance system. If an Eddy carb is being used on the timed port then this setup does not work too well.
I'm actually starting to think that running a vac system on the non-timed port might be better. Then with this setup aim for around 18-20 degrees at idle. The all in with no vac (at WOT) would still need to be 28-30, all in with the throttle just cracked open could be much more and this would be OK.
One day I might try all of this as I run a programmable MSD. Figures off the top of my head would be something like:-
20 at idle with 14 being made up by what the vac system is adding, the other 6 being the static timing figure.
Then when the throttle is booted from tickover the timing would back off to 6 but would start to climb as the revs rise. Assuming that the throttle is floored all the way to the redline this figure would climb due to the bob weights to 30 degrees all in at 2750-3000 RPM. Then if the throttle was backed off the extra 14 degrees that the vac system can provide would kick in giving 44 degrees in total.
The reason that I think that the timing should actually back off it that at just above idle or low RPM with the throttle just cracked is that the VE is very poor so the charge needs to be lit much earlier. BUT at low RPM with your foot on the floor the VE is very high so the peak cylinder pressure BEFORE the charge is lit is high, this means that there will be a rapid burn rate, this means that less advance is actually required. Also as the RPM is low there is more time for the burn to complete before the piston rushes back down the bore on the power stroke.
Having said all that I can't quite be arsed to try it out! (I did notice that an old mini I was working on it used the non-timed port, and I reckon it was for the reasons that I have described above).
Thanks for the replies, I'm running twin SU carbs (standard size) and will have a go with the vac advance connected at first I think.
I don't know what the CR is, the blocked was planed after fitting the top-hat liners and the heads were also planed to remove bad pitting (looked like some stones had been ingested) but I didn't think to measure it before bolting the heads on.
Maybe I can hook an old spring to a new one and see how much they stretch? If it gives differences I can measure there is a table in the spring kit I can use to work out roughly what the standard springs are.
I'll turn up a steel sleeve to restrict the advance, hopefully if everything is clean, oiled and moving freely I should be able to measure it fairly accurately...
I don't know what the CR is, the blocked was planed after fitting the top-hat liners and the heads were also planed to remove bad pitting (looked like some stones had been ingested) but I didn't think to measure it before bolting the heads on.
Maybe I can hook an old spring to a new one and see how much they stretch? If it gives differences I can measure there is a table in the spring kit I can use to work out roughly what the standard springs are.
I'll turn up a steel sleeve to restrict the advance, hopefully if everything is clean, oiled and moving freely I should be able to measure it fairly accurately...
