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| Shift rpm??? https://www.slantsix.org/forum/viewtopic.php?t=14404 |
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| Author: | Rust collector [ Fri Sep 16, 2005 4:57 pm ] |
| Post subject: | Shift rpm??? |
I don´t race, but I was wondering anyway... Do you shift at the same rpm in every gear? I had a little test last week in the truck at work, and it goes a lot faster if I almost peg the tach in the first gears, and go to a lower shift rpm in the taller gears  Guess big diesel lowend torque has something to do with it, but anyway... |
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| Author: | slantzilla [ Fri Sep 16, 2005 5:00 pm ] |
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Shift RPM depends mostly on cam, carb, and headwork. Stock motors probably will run faster lowering the shift point in each gear. On juice I have started shifting mine at 6100, both shifts. 
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| Author: | Rust collector [ Sun Sep 18, 2005 12:36 pm ] |
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Ok, thanks! |
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| Author: | Doctor Dodge [ Tue Sep 20, 2005 9:12 pm ] |
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Every engine seems to have a different "sweet spot" for shift points, on the current stock 225 1 bbl with a small shot of spray, shifting at 4600 RPMs gets the fastest ET  DD |
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| Author: | 1966 dart wagon [ Tue Oct 18, 2005 2:40 pm ] |
| Post subject: | |
Quote: Every engine seems to have a different "sweet spot" for shift points, on the current stock 225 1 bbl with a small shot of spray, shifting at 4600 RPMs gets the fastest ET
my motor almost fell flat on its face if i ran it up to 4500, and dam she was screaming at me DD so i was shifting at about 3800 was pretty good but my motor is bone stock and normally didnt run to well 
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| Author: | 70valiant [ Tue Oct 18, 2005 7:00 pm ] |
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I shift at 42-4300rpm it just falls flat after that. I'm not sure why though. I have ported the head, headers, 4 barrel, mild cam and electroninc ignition. I thought it would rev harder after all those mods. |
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| Author: | Dennis Weaver [ Tue Oct 18, 2005 8:05 pm ] |
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Quote: I shift at 42-4300rpm it just falls flat after that. I'm not sure why though. I have ported the head, headers, 4 barrel, mild cam and electroninc ignition. I thought it would rev harder after all those mods.
4.125" stroke.  D/W |
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| Author: | Dart270 [ Tue Oct 18, 2005 9:08 pm ] |
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Phil, I would suspect either cam timing too far retarded (degreed?) or ignition timing too far advanced. With those mods, you ought to at least get 4500-5000 outta it. My 68 Dart with MP 0.436" cam, bone stock head, and 8:1 comp revs hard to 4600, and will pull OK to 5000. Timing, induction, and exhaust are pretty tuned up. Lou |
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| Author: | Rust collector [ Wed Oct 19, 2005 7:11 am ] |
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Wow! is this thread still around Oh well, keep it going. |
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| Author: | emsvitil [ Wed Oct 19, 2005 2:32 pm ] |
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Actually, an advanced cam will make your top end go away....... |
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| Author: | 70valiant [ Wed Oct 19, 2005 4:00 pm ] |
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it will pull hard to 4300 and will rev higher but it looses power quickly after 4300 I did wind out first gear to almost 5000 once and it made a REALLY loud pinging sound. It will just stop accelerating in 3rd gear at 4500 rpm(105mph with the 3.23's, 90mph with the 3.91's). I was expecting it to rev higher with the 465 holley over the BBD but no dice. I really need to get some timing tape and see what my total advance is. my inital is 11* and will still ping occasionally using 93 octane(compression is around 9.8:1). |
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| Author: | Dennis Weaver [ Wed Oct 19, 2005 4:03 pm ] |
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Quote: it will pull hard to 4300 and will rev higher but it looses power quickly after 4300 I did wind out first gear to almost 5000 once and it made a REALLY loud pinging sound. It will just stop accelerating in 3rd gear at 4500 rpm(105mph with the 3.23's, 90mph with the 3.91's). I was expecting it to rev higher with the 465 holley over the BBD but no dice.
...that sounds like a lot of timing for a /6. What's your total mechanical timing? I bet that's your issue.I really need to get some timing tape and see what my total advance is. my inital is 11* and will still ping occasionally using 93 octane(compression is around 9.8:1). D/W EDIT: Duh, I need to learn to read your whole post before I respond!  Yeah, get the tape or a dial-back light, OR, just use your tab scale as a guide to mark off 5 deg. increments on your damper. Crude, but it'll give you an idea without any real effort...
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| Author: | Dave M [ Wed Oct 19, 2005 4:06 pm ] |
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I shift my race engine at 6200 RPM big cam big valves and injection....I have tried higher RPM but the car does not run any faster. Dave M |
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| Author: | Dart270 [ Wed Oct 19, 2005 7:01 pm ] |
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Yep, I bet it's ignition advance. Most early dizzys I've seen would give almost 40 deg total mech with 11 deg initial - WAYYY too much. You want 27-30 deg total mech with that comp and setup. You could pick up as much as a whole second in the 1/4 just by recurving your dist and moving total mech down to about 28 deg. Been there... Ed, you are completely correct. I misspoke - an advanced cam would limit upper RPM power. My mistake. Dave, what's up with your bad self! Things are good in NC and I'm looking forward to some road racing in a coupla weeks. Lou |
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| Author: | ateam [ Wed Oct 19, 2005 7:42 pm ] |
| Post subject: | timing |
what inital timing are you working with? |
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