.050 vs. .009
02-14-2008, 07:55 PM
#2
The Hoffinator
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yes it is. It does not have the proper advance curve for these engines. an 050 is closer, but isnt correct either. idealy you shoudl use an 031, an 022 or an 061, which were all original to these cars. if you have one and they are worn out, send it to Don Marks up in oregon and he will rebuild it for you and calibrate it correctly using a sun distributor machine. now.. that being said, an 050 is close, and works OK, just not idealythe 050 is no longer made and is getting harder to find. an 009 doesnt even come close in its advance curve so shoudl be chucked in the trash or sold on ebay. now there is yet another option available out there, which is the rsr0012 custom made by John Benton for Classic and Speed Parts, a company in southern california that specializes in custom and restoration parts for 912s, 356s and 911s. the RSR0012 is actually an 009 that has been taken apart, and rebuild and recurved on a sun distributor machine so that it has teh correct curve for a 912. You can buy an RSR0012 from CSP for about 200 or so. you can have an 031, 022 or 061 remanufactured by don marks for somehwere between 2 and 300.. but im not sure of the exact cost anymore.
here is somthing from the 912BBS.ORG that illustrates all of this
the graph should give you a good visual of why not. 
here is somthing from the 912BBS.ORG that illustrates all of this
Here is how to read this graph.
The curves show the RPM that the advance starts to take effect.
For the 022, that is 750 RPM, for the 050, 900 RPM, and for the RS0012, 1100 RPM. The 050 and the Don Marks 031 have the same start points.
That means that you can set the idle speed higher with the RS0012 and not get into the range where the distributor starts advancing. This is a common problem with the 022 because the advance begins at 750 RPM and usually people like to set the idle around 900 RPM. This makes the idle speed hard to get to settle when decelerating.
The Total advance is 30 degrees for the RS0012, the 022, and the 050. So the initial advance settings are the same for these three distributors. It should be around 2 - 3 degrees initial advance, for a total of 32 to 33 degrees total advance.
The Don Marks distributor total advance is 26 degrees, so the initial advance for this distributor should be set to 6 - 7 degrees to achieve the same total advance of 32 to 33 degrees. That means that you have more initial advance which makes the engine run a little faster and you can close the throttle butterflies off a little more at idle. This also may help low speed acceleration.
Note That the DM 031 and the B 022 have similar curves in the mid range, with a noticeable bump. This means that the advance comes in sooner giving the engine a little more torque in the mid range. This type of curve was introduced in the 356B design. The 356A curve was similar to the RS0012, with a linear slope.
Now you can see that the 009 advance curve is completely different. It has only 22 degrees total advance and doesn't get there until 3300 RPM. This means that the 009 must have at least 10 degrees initial advance to reach full advance appropriate for the Porsche engine. Plus the advance curve has a flat plateau at 6 degrees up to 2200 RPM. This will rob your engine of midrange power and this confirms the general experience with this distributor.
A common problem with old distributors that have worn shaft bearings is instability in the timing. Also If the set screw cannot be tightened down, the gap will change over time. This will cause the timing to change. These problems can be fixed by using the Pertronix sensor, which is not sensitive to shaft wobble or points wear. Some of the 050 distibutors made in Mexico had lousy shaft bearings out of the box.
From this discussion, I think it is clear that there is no clear "best" advance curve. Perhaps the RS0012 comes the closest, but the 050 and the stock curves are also OK. There is however one "worst" advance curve.
SV
The curves show the RPM that the advance starts to take effect.
For the 022, that is 750 RPM, for the 050, 900 RPM, and for the RS0012, 1100 RPM. The 050 and the Don Marks 031 have the same start points.
That means that you can set the idle speed higher with the RS0012 and not get into the range where the distributor starts advancing. This is a common problem with the 022 because the advance begins at 750 RPM and usually people like to set the idle around 900 RPM. This makes the idle speed hard to get to settle when decelerating.
The Total advance is 30 degrees for the RS0012, the 022, and the 050. So the initial advance settings are the same for these three distributors. It should be around 2 - 3 degrees initial advance, for a total of 32 to 33 degrees total advance.
The Don Marks distributor total advance is 26 degrees, so the initial advance for this distributor should be set to 6 - 7 degrees to achieve the same total advance of 32 to 33 degrees. That means that you have more initial advance which makes the engine run a little faster and you can close the throttle butterflies off a little more at idle. This also may help low speed acceleration.
Note That the DM 031 and the B 022 have similar curves in the mid range, with a noticeable bump. This means that the advance comes in sooner giving the engine a little more torque in the mid range. This type of curve was introduced in the 356B design. The 356A curve was similar to the RS0012, with a linear slope.
Now you can see that the 009 advance curve is completely different. It has only 22 degrees total advance and doesn't get there until 3300 RPM. This means that the 009 must have at least 10 degrees initial advance to reach full advance appropriate for the Porsche engine. Plus the advance curve has a flat plateau at 6 degrees up to 2200 RPM. This will rob your engine of midrange power and this confirms the general experience with this distributor.
A common problem with old distributors that have worn shaft bearings is instability in the timing. Also If the set screw cannot be tightened down, the gap will change over time. This will cause the timing to change. These problems can be fixed by using the Pertronix sensor, which is not sensitive to shaft wobble or points wear. Some of the 050 distibutors made in Mexico had lousy shaft bearings out of the box.
From this discussion, I think it is clear that there is no clear "best" advance curve. Perhaps the RS0012 comes the closest, but the 050 and the stock curves are also OK. There is however one "worst" advance curve.
SV
02-15-2008, 01:48 AM
#4
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Can't say much about the 009 replacement - but, I just replaced my stock (063? or something maybe?) distri with a RS0012 from Will at Classic and Speed Parts...
The car just had a timing and tune up from a reputable shop, so I figured the car was at its best it could be... I put in the RS0012 and there was a noticeable difference. The Solex-stumble is still there around 1800rpm, but, the car runs well higher and quicker (RPM wise) than it did prior to the distributor change.
I still have the igniter to replace the points.. but the change of the distributor was enough to keep me happy for a while. I'd recommend it if you don't know the history of what you have now...
-Mike
The car just had a timing and tune up from a reputable shop, so I figured the car was at its best it could be... I put in the RS0012 and there was a noticeable difference. The Solex-stumble is still there around 1800rpm, but, the car runs well higher and quicker (RPM wise) than it did prior to the distributor change.
I still have the igniter to replace the points.. but the change of the distributor was enough to keep me happy for a while. I'd recommend it if you don't know the history of what you have now...
-Mike
02-15-2008, 01:51 AM
#5
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Ah, Harry,
I'm going to try to make it over on Saturday.. I might throw the 912 off the jack stands and drive it over...or take the 964 (rust proof! well, galvanized...).
Does the place serve beer? I can't do Saturday morning without beer....
-Mike
I'm going to try to make it over on Saturday.. I might throw the 912 off the jack stands and drive it over...or take the 964 (rust proof! well, galvanized...).
Does the place serve beer? I can't do Saturday morning without beer....
-Mike
02-15-2008, 10:11 AM
#6
The Hoffinator
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Hi Mike, its actually on sunday the 17th, at 11 AM, Buca De Beppo
60 East Wilson Bridge Road
Worthington, OH 43085
directions can be found:
http://www.bucadibeppo.com/locations...?location=3505
I m pretty sure they surve beer; not sure if they do sunday mornings though..
60 East Wilson Bridge Road
Worthington, OH 43085
directions can be found:
http://www.bucadibeppo.com/locations...?location=3505
I m pretty sure they surve beer; not sure if they do sunday mornings though..
02-17-2008, 11:56 AM
#7
Track Day
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Thank you both for your info! I'll contact Don and have him check out my existing distributor.
'05 Subaru Legacy Wagon
'31 Ford 5 window Coupe
'73 VW KG 'Vert w/'67 912
'57 Speedster - Sold
'63 Porsche Sunroof Coupe - Sold
'74 Pantera L - Sold
SLC, Utah
'05 Subaru Legacy Wagon
'31 Ford 5 window Coupe
'73 VW KG 'Vert w/'67 912
'57 Speedster - Sold
'63 Porsche Sunroof Coupe - Sold
'74 Pantera L - Sold
SLC, Utah
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02-18-2008, 12:32 PM
#11
The Hoffinator
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all of those are bosch cast iron units, and all pretty much look identical unless you look at the part number (which the last digits will tell you 009, 022, 031, 050, 061, etc...)
there are subtle differences, i think the 022 and maybe 061 tends to have a darker body, and the distributor caps tend to be different colors for them. either way, i would just check the parts number on it and be safe, and sure of what you have
there are subtle differences, i think the 022 and maybe 061 tends to have a darker body, and the distributor caps tend to be different colors for them. either way, i would just check the parts number on it and be safe, and sure of what you have