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| Determining Lobe Spread? Other measurements needed? https://slantsix.org/forum/viewtopic.php?t=45078 |
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| Author: | drtwgn [ Mon May 23, 2011 4:10 pm ] |
| Post subject: | Determining Lobe Spread? Other measurements needed? |
Hi gurus Finally figured out some of the cam specs by degreeing, and not sure if this cam is advanced 3 degrees or none, and not sure if I need to measure/verify the lobe spread. Here is the card info CLevite Cam 2291380 Intake cam lift 270 I meas. 266 Exh cam lift 276 I meas 274 Intake & Exh duration 244 Int valve open 8 I get 8 Int valve close 26 I get 25 Ex valve open 33 I get 33 Ex valve close 10 I get 12 Intake center line 106 I get 106 Exh lobe center 112 I didn't check Lobe Spread 109 1)IS this cam pre advanced from Clevite? 2)Do I need any more measurements, or am I all set? 3)Based on the below mods, would advancing even be that necessary? It will just be a daily driver, and economy is more important that quarter mile stats. The head is ported, with double springs, std size valves 9.0:1 compression, split exhaust manif (not sure on duals or a collector) 2 inch exh pipe(2) Will start with a 1 bbl carb 14 inch tires Not sure but probably the 2.76 rear. 4) With this setup, are duals really necessary? How much hp could one expect to pick up with honest duals vs. a collector? THANKS, PEACE. Donation Sent!!! |
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| Author: | CNC-Dude [ Mon May 23, 2011 5:07 pm ] |
| Post subject: | |
It looks as if the cam is "straight up" according to your cam card specs. Your lobe spread, or lobe seperation angle is fixed, and cannot be changed by advancing or retarding the cam, only by regrinding. What standard are they giving these specs to you...@.020 lift, @.050 lift, etc. |
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| Author: | drtwgn [ Tue May 24, 2011 8:00 am ] |
| Post subject: | Determining Lobe Spread? Other measurements needed? |
At .05" |
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| Author: | Doc [ Tue May 24, 2011 8:20 am ] |
| Post subject: | |
Looks like that cam could be advances a couple of degrees more... What is the intake close point, when checked at .010 lash? DD |
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| Author: | drtwgn [ Tue May 24, 2011 2:00 pm ] |
| Post subject: | Determining Lobe Spread? Other measurements needed? |
I don't know how to check that. Sounds like I need to put head and rocker arms on...... Advancing bumps up low end torque, but what does it do to economy at in town speeds? That's likely where most of my driving will be. If I left it straight up at 106, would mid range torque increase that much, and what would that do to hwy fuel economy, given above car's data? With a cr of 9 to 1, am I really going to notice any effect by advancing? |
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| Author: | Doc [ Tue May 24, 2011 3:43 pm ] |
| Post subject: | |
If you really have 9 to 1 static compression then this cam is going to give you a pretty high DCR either way... That said, try it where it is... there won't be a big difference. DD |
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| Author: | SlantSixDan [ Tue May 24, 2011 4:14 pm ] |
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To my eye (and per my parts catalogues) this is a stock '71-'80 camshaft. Doc, others? Agree, disagree? |
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| Author: | drtwgn [ Wed May 25, 2011 7:20 am ] |
| Post subject: | Determining Lobe Spread? Other measurements needed? |
The card says Dodge, Chrysler car, truck '60-82. Static compression may be 8.9 :1. Brings up a good lesson: for all you guys and gals, double checking your numbers is a good habit - I measured my piston to deck distance prior to dissasembly. I told the machinist how much to take off to get 9:1. I put the new pistons in with the machined block, and "Hey, man!". Pistons were about .1" shorter than the originals. It cost me $75 to get block re shaved. Never considered new piston height. Now I know better..........this whole project has taught me lots of things about this motor I never knew before. And thanks to all you "tool using mammals", I avoided lots of other mistakes. I only spent $75 unneccessarily. PEACE |
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| Author: | SlantSixDan [ Wed May 25, 2011 8:58 am ] |
| Post subject: | Re: Determining Lobe Spread? Other measurements needed? |
Quote: The card says Dodge, Chrysler car, truck '60-82.
Bzzt! No such cam. '60-'80, yes. Starting in '81, the slant-6 got hydraulic lifters and a different, non-interchangeable cam.
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| Author: | drtwgn [ Wed May 25, 2011 3:14 pm ] |
| Post subject: | Determining Lobe Spread? Other measurements needed? |
I don't know how to check that. Sounds like I need to put head and rocker arms on...... Advancing bumps up low end torque, but what does it do to economy at in town speeds? That's likely where most of my driving will be. If I left it straight up at 106, would mid range torque increase that much, and what would that do to hwy fuel economy, given above car's data? With a cr of 9 to 1, am I really going to notice any effect by advancing? |
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