View Full Version : Check Your Eccentric Cone!
02-04-2003, 02:54 PM
Today I was fine tuning my pump on the 92. Since the 90 model feed truck was right by it. I decided to pull the diapraghm off of both. After I got the 4 cap diapraghm off, I noticed that the 90 models eccentric cone was tapered alot more(allowing farther pin travel) than my 92's. The 90 models eccentric also showed a different stamped part number than the 92. The 90 models was a 75 while the 92's was a 70H. This can be found on the bottom of the eccentric cone. So, I switched the 90 models 75 into the 92 and took it for a ride. You could definately tell a difference. In fact, instead of boost stopping at the 32-33 mark, she went right on up to the 35 mark. Quickness of the truck off of acceleration was definately noticed between the two. So, if you havent already, check your eccentric number, and, if you can find a donor on a non intercooled to compare. The 90 model is a 3/4 4wd Automatic with a CPL of 0807 and the 92 is CPL # 1351.
02-04-2003, 03:43 PM
Good observation! <br><br>Mine doesn't have any numbers on it. It looks like a custom machined unit. ??? [laugh]<br><br>My original one was a 70S.<br><br>Mike<br>
02-04-2003, 03:56 PM
70S? Hmm.. Wonder why so many choices. Could it be that the automatics got a deeper cone to aid in quicker spoolup? I didnt get the caliper out or anything, but I could definately tell a big difference in the two.
Funny -- I asked someone who supposedly could order all parts Bosch if there were different eccentrics available for the our pumps. They said no. <br><br>Monty -- can you measure the the two pins and check to see if the two AFC springs are the same? I will try to pull my pin and check the number and post its dimensions . . .of course, with my to do list, it could be months before I get there . . .<br><br>Smoky, what dimensions did you finally go with on your custom part?<br><br>Thanks for the info Monty!
02-04-2003, 04:31 PM
I will see what I can do. I did notice that the spring was a green and black color while the spring on my truck was an all silver spring, no color. I did push them down at the same time with my hands and they both seemed to have the same tension though. But, you never can tell. When I first got the truck, I let a retired Cummins engineer play with it, so he may have switched out springs.
I will see what I can do tommorrow.
02-04-2003, 04:35 PM
Mine is a 70H. Ist the taper steeper or just offset more?<br><br>Jay
02-04-2003, 04:54 PM
The 75 (90 model) had a deeper look to it all the way up the eccentric.
02-04-2003, 05:58 PM
Do i understand this correctly?<br> The cone tapers down to a smaller diameter at the southbound end. As the boost pressure at the diaphram above the cone increases, the cone is forced downwards, increasing the metered amount of fuel supplied to the engine "richening" to compensate for the higher amount of air supplied by the turbo.<br> This in mind, the cone in the 90' as described in the first post here, must have a greater pitch than the original from the 92'? The increased fuel would cause the higher boost reading he is getting.<br> Makes sense, but how do we find out how to get them thar cones??<br> -RATCHET-
02-04-2003, 08:25 PM
Yessir, your explanation is correct. Where to get them, that is another story. I guess you could always switch them out when another 1st genner isnt looking. [laugh]<br><br>FWIW...Bosch should be able to get one if you give them the number that I posted.
02-04-2003, 10:54 PM
asilitch,<br>I finished drawing up another design Sunday. This one is NOT liner. It has a compounding radius (does that make sense?) that is larger at the bottom and smoothly steps down to the top. It is now on AutoCAD, and will be machined on a CNC. I would post a picture but haven't got that figured out on this site yet. The final unit should be quite "tunable." I am trying to make everyone happy here. The idea is that it can be set mild for no/low smoke, and wild for high low-end torque and fast turbo spool up. It will be hardened to something like 50 on the Rockwell scale (cant remember right now), unlike the DD pin. ::) <br><br>Seems to be a few of options for the different years and models.<br><br>
02-05-2003, 06:19 PM
Jbolt, I havent had a chance to take any measurements of the two yet. Any of you guys running the non intercooled trucks care to take a peak at your eccentric and tell me what you find? Im curious to see how many different eccentric versions are out there.
02-05-2003, 09:05 PM
Your more than welcome to come take a look for yourself. While your at it, show me how to set timing, and turn up the fuel. <br><br>Learning fast, but I'm sure you'll have an answer before I'm of any use (eagerly waiting for results).<br><br>Don
02-06-2003, 05:49 AM
I will check mine on my early 91 and let you know.
I just checked mine....it is a 75
02-06-2003, 06:37 AM
<br>Jbolt, I havent had a chance to take any measurements of the two yet. Any of you guys running the non intercooled trucks care to take a peak at your eccentric and tell me what you find? Im curious to see how many different eccentric versions are out there.<br> been a long time since i had mine out. i think it had the #45 on it. when i get time will check it again.
02-06-2003, 09:49 AM
This all explains how my 89 "seemed" alot faster off the line than my 93 even without any governor adjustments. I never thought that the eccentrics would be different in cone taper angle... I should have swapped them before I sold it... :'(
I have a pic of the cone on my 89, just at and angle shot.. Not much use but I attached it anyway..
I still haven't had a chance to get the number or dimensions from my cone.<br><br>I have been thinking about the radiused eccentric, though, and I was wondering if I could get Smoky to elaborate a little more on why he chose to increase the fuel more quickly with respect to boost at lower manifold pressures. Unless the idea is that you can choose wich portion of the curve you are using? So that with the same pin you could have either a very steep slope or flatter slope? But I am not sure that there is room to adjust the eccentric that much -- or do I not get it?<br><br>I am curious for an update on that modification, though.<br><br>Thanks,<br><br>Alec
02-11-2003, 04:51 PM
The newest design will look similar to the old in that there will only be one setting. The cut needs to be deep enough to allow for full guide pin travel. If two settings were made there wouldn’t be enough material to attach the "cone" to the shaft. What I meant when I sad "tunable" is that it can be adjusted to fit a variety of personal preferences using the star wheel and smoke screw. It won't be a racing, or a super econo design. But rather a good compromise between the two. There are actually three parts to the profile. The first is a fairly large radius, next is a smaller radius, and the last portion is a liner cut. It is all blended together to form a seamless path that looks like a constant radius. I will give another update once it it finished and tested.
02-13-2003, 12:31 PM
<br>Jbolt, I havent had a chance to take any measurements of the two yet. Any of you guys running the non intercooled trucks care to take a peak at your eccentric and tell me what you find? Im curious to see how many different eccentric versions are out there.<br> checked mine today it is a #56
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