13b Versions?
06-11-2003, 12:51 PM
#21
Senior Member
Join Date: Nov 2001
Posts: 2,284
Ah, Spaceballs. 
I think FC and FB pullies are exactly the same size. Well, I'll know soon enough.
Ok, I've got them both sitting here and the size difference is very small. I bet it'll be so close that it won't really affect anything.
Oh man, it's like 361mm with my cloth tape measure wrapped around it. It's also a hair larger than the FB pulley when held end to end. I guess that's where the extra mm comes from. I'm not too worried. I'll just measure from both directions and average the marks before I cut them with a small triangle file. The only part that worries me is getting it lined accurately up on the 20B hub.
The FC has a 15º L/T split. This FB pulley has a 20º split. I think the 20B also has a 15º split. Somebody once said it did. I could find out from my pulley, but I don't want to bother with the mathmatics.
I think FC and FB pullies are exactly the same size. Well, I'll know soon enough.
Ok, I've got them both sitting here and the size difference is very small. I bet it'll be so close that it won't really affect anything.
Oh man, it's like 361mm with my cloth tape measure wrapped around it. It's also a hair larger than the FB pulley when held end to end. I guess that's where the extra mm comes from. I'm not too worried. I'll just measure from both directions and average the marks before I cut them with a small triangle file. The only part that worries me is getting it lined accurately up on the 20B hub.
The FC has a 15º L/T split. This FB pulley has a 20º split. I think the 20B also has a 15º split. Somebody once said it did. I could find out from my pulley, but I don't want to bother with the mathmatics.
06-11-2003, 01:26 PM
#22
Senior Member
Join Date: May 2002
Location: California
Posts: 22,465
the cosmo is the missing link between the s5 t2 and the fd. so i'd bet its an fc 15degress split. i should make clear too, that my 120 and 240 marks arent all that accurate, they are just close, i needed to make sure it had the right firing order
mike
mike
06-11-2003, 03:18 PM
#23
Senior Member
Join Date: Nov 2001
Posts: 2,284
Ah, and the 20B has S5 rotors in it. I guess the rest depends on the plug locations in the rotor housings. I've got a T2 housing sitting within my 20B mock-up made from three FC and one '76 Cosmo housings and FB side plates.
While hand cranking my 20B, I can see that the apex seals pass by in order of 1-2-3. Perhaps the 13G had a different order, but I'm pretty sure all 20Bs had 1-2-3.
My pulley has to be as accurate as possible because the three pickups in the dizzy have to be aligned with the marks on the pulley. Talk about setting your timing the hard way! Oh well, the trade-off is to have dual Leading sparks per rotor face like FC and later 13Bs. I can't wait to hear it run in this configuration.
While hand cranking my 20B, I can see that the apex seals pass by in order of 1-2-3. Perhaps the 13G had a different order, but I'm pretty sure all 20Bs had 1-2-3.
My pulley has to be as accurate as possible because the three pickups in the dizzy have to be aligned with the marks on the pulley. Talk about setting your timing the hard way! Oh well, the trade-off is to have dual Leading sparks per rotor face like FC and later 13Bs. I can't wait to hear it run in this configuration.
06-11-2003, 05:58 PM
#24
Senior Member
Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by Jeff20B' date='Jun 11 2003, 12:18 PM
Ah, and the 20B has S5 rotors in it. I guess the rest depends on the plug locations in the rotor housings. I've got a T2 housing sitting within my 20B mock-up made from three FC and one '76 Cosmo housings and FB side plates.
While hand cranking my 20B, I can see that the apex seals pass by in order of 1-2-3. Perhaps the 13G had a different order, but I'm pretty sure all 20Bs had 1-2-3.
My pulley has to be as accurate as possible because the three pickups in the dizzy have to be aligned with the marks on the pulley. Talk about setting your timing the hard way! Oh well, the trade-off is to have dual Leading sparks per rotor face like FC and later 13Bs. I can't wait to hear it run in this configuration.
While hand cranking my 20B, I can see that the apex seals pass by in order of 1-2-3. Perhaps the 13G had a different order, but I'm pretty sure all 20Bs had 1-2-3.
My pulley has to be as accurate as possible because the three pickups in the dizzy have to be aligned with the marks on the pulley. Talk about setting your timing the hard way! Oh well, the trade-off is to have dual Leading sparks per rotor face like FC and later 13Bs. I can't wait to hear it run in this configuration.
06-12-2003, 01:31 AM
#25
Senior Member
Join Date: Nov 2001
Posts: 2,284
That pic takes me back to late '01 when I was first getting a real idea of all the geometry of the 20B's firing order for two Leading sparks. I used my old drafting "mad skillz yo" and came up with a couple different drawings. Then last summer I got back into it and drew some patterns on some cereal box paperboard and traced around them onto some sheet metal.
This was the beginning of my 20B dizzy prototype, complete with Trailing pickups mounted above the Leading ones.
I doubt I'll even hook up Trailing, to tell you the truth. It just doesn't add enough power to the engine. The second Leading sparks sort of do the job anyway. My REPU's engine's idle and low to mid RPM was unchanged. Only high RPM under high load lost like 1HP with Trailing switched off. I'm guessing it was only 1HP because it was barely detectable by myself and a friend, and my electric fan was replaced by a clutch fan and it sucked a lot more power. A lot more! People say those clutch fans use like 5HP. If so, and I could feel it that much, it's probably going out, or my REPU's engine has a lot less than 100HP, or the engine's RPM is low enough to only be producing maybe 50RWHP where it feels sluggish with the fan. The lower the total engine HP, the more a loss of 5HP can be felt. Well, at low RPM, trailing did absolutely nothing for my engine. Pretty weird huh? I could put two of the three pickups back into a stripped dizzy I guess.
I'll see about some audio clips of the 20B once it's running. You can then tell me if it sounds different than everyone else's.
This was the beginning of my 20B dizzy prototype, complete with Trailing pickups mounted above the Leading ones.
I doubt I'll even hook up Trailing, to tell you the truth. It just doesn't add enough power to the engine. The second Leading sparks sort of do the job anyway. My REPU's engine's idle and low to mid RPM was unchanged. Only high RPM under high load lost like 1HP with Trailing switched off. I'm guessing it was only 1HP because it was barely detectable by myself and a friend, and my electric fan was replaced by a clutch fan and it sucked a lot more power. A lot more! People say those clutch fans use like 5HP. If so, and I could feel it that much, it's probably going out, or my REPU's engine has a lot less than 100HP, or the engine's RPM is low enough to only be producing maybe 50RWHP where it feels sluggish with the fan. The lower the total engine HP, the more a loss of 5HP can be felt. Well, at low RPM, trailing did absolutely nothing for my engine. Pretty weird huh? I could put two of the three pickups back into a stripped dizzy I guess.
I'll see about some audio clips of the 20B once it's running. You can then tell me if it sounds different than everyone else's.
06-12-2003, 12:23 PM
#27
Senior Member
Join Date: Nov 2001
Posts: 2,284
That's interesting how it would change like that. I'll be running 20-24º of total advance. My 20B prototype was built on a 12A dizzy.
I'm brainbashing some possible 20B project cars in the Ask Mike section of one of the other forums you visit regularly. Let me know what you think about some of my crazy ideas (MG vs GLC).
I'm brainbashing some possible 20B project cars in the Ask Mike section of one of the other forums you visit regularly. Let me know what you think about some of my crazy ideas (MG vs GLC).