Just make certain your state of tune is right on before you let the Genie out of the bottle!
CJ
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| Hesitations plague me once again https://www.slantsix.org/forum/viewtopic.php?t=38419 |
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| Author: | 1974duster kev [ Sat Dec 26, 2009 2:31 pm ] |
| Post subject: | Hesitations plague me once again |
So i haven't posted in a while hi again everyone been busy trying to pass my classes and with work. To the point the duster seemed to have pretty good throttle response finally but then i went ahead and took out the 904 and tossed a 833 od tranny in there "love it". but now i have a list of throttle response issues that i may have caused with tinkering or just the tranny swap. In nuetral i can rev nicely with blips of the throttle but.. when i put the pedal to the floor hesitates then revs up seems the fast i put the pedal to the floor the worse when doing this test. When road testing if punched more then half throttle it bogs kinda like a shutter then goes seems lean to me. from a slow role in 1st gear ill punch it nose dives then scoots with power. I have a 390cfm holley vac secondaries. it's a built motor 270 cam maybe compression in the 9's took .100 of the head. Seemed like the 50 size pump shooter is helping things but that seems like its to big and im just covering other problems. I could use any ideas or knowledge thanks. Kev |
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| Author: | DusterIdiot [ Sat Dec 26, 2009 4:36 pm ] |
| Post subject: | Yep... |
What pump cam are you using? It's typical that if using a big shooter but a small cam you get one big shot but it doesn't last long enough to cover the whole lack of vacc. until the PV and mains/secondaries come on line. You shouldn't need much more than a 31 and an Orange...On the hyperpak manifold it likes a nice "long" shot so it uses a pink cam... Also what PV are you using? 6.5,8.5, 10? Have you been driving with a vacc. gauge hooked to the base of the carb to see exactly when it 'falters off'? -D.Idiot |
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| Author: | 1974duster kev [ Wed Dec 30, 2009 3:14 am ] |
| Post subject: | |
i have to orange cam on right now i had a 35 shot on ran worse when i got up to 50 pump shot it is actually pretty decent. dunno about vacum my pv is lets see at idle i had 14lbs vacum. i have a 5.5 pv. i dont have a vacum gauge at the moment to be able to keep an eye on the vacum falling off. Thank Kev. |
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| Author: | ceej [ Wed Dec 30, 2009 6:31 pm ] |
| Post subject: | |
your running a 50cc pump on the 390? Shouldn't need that. The 30cc should do the trick. Are you on screw hole 1 or 2 on the Orange cam? Try screw position 2 and make sure the pump gap is set up right. What shooter have you got on there? 28 should do it. Ditch the 5.5 in HG PV and install a 10.5" HG standard flow Holley PV. The 5.5 won't start working till your way lean. CJ |
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| Author: | DusterIdiot [ Wed Dec 30, 2009 8:19 pm ] |
| Post subject: | Yep! |
Quote: your running a 50cc pump on the 390?
Exactly my thoughts!Shouldn't need that. The 30cc should do the trick. Are you on screw hole 1 or 2 on the Orange cam? Try screw position 2 and make sure the pump gap is set up right. What shooter have you got on there? 28 should do it. Ditch the 5.5 in HG PV and install a 10.5" HG standard flow Holley PV. The 5.5 won't start working till your way lean. CJ I second the motion! -D.Idiot |
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| Author: | 1974duster kev [ Sun Jan 03, 2010 8:21 pm ] |
| Post subject: | |
sounds good to me ill try it out. i'll let you guys know my pump shot is at 50 heh i thought it was way to much but it ran better with bigger pump shot so i figured why not keep going up. the pv makes sense it seems like a really lean bog thanks fellas ill let ya know the outcome. kev |
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| Author: | 1974duster kev [ Wed Jan 06, 2010 9:36 am ] |
| Post subject: | |
I forgot to mention im installing a larger cam from the erson 270 up to 238@. 50 with .510 lift on a 108 lobe center so would the 10.5 pv still be what i want to install? I ask this question because im assuming my vacuum will be less with the bigger cam? Thanks,kev |
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| Author: | SV162 [ Thu Jan 07, 2010 4:05 am ] |
| Post subject: | |
I'd say you will need to change the PV. Just get a vac reading with the new cam in and you'll know what PV you need. |
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| Author: | 1974duster kev [ Sat Jan 09, 2010 6:53 am ] |
| Post subject: | |
well, the bigger cam should be here soon from erson im hoping to see some improvement over the erson 270 cam. The new cam is 238@ .50 with .510 lift on a 108 lobe should be nice and rumpy and some good fun with the 4spd now. "oh and a 100 shot plate kit is also under the hood now" Sorry i was exited had to post this to my fellow slanters. I should be racing again soon then ill actually have some updates to post. Kev |
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| Author: | ceej [ Sat Jan 09, 2010 8:35 am ] |
| Post subject: | |
Just make certain your state of tune is right on before you let the Genie out of the bottle! CJ |
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| Author: | SV162 [ Sun Jan 10, 2010 5:40 pm ] |
| Post subject: | |
Quote: "oh and a 100 shot plate kit is also under the hood now" Let the fun begin 
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| Author: | 1974duster kev [ Sun Jan 31, 2010 7:42 pm ] |
| Post subject: | |
Ok so the motor is back together and running fine after some carb adjustments. the bigger cam rumps nicely at 700rpm im trying to be nice on the break in so no real power details yet, but my throttle response is almost their i'd say 90% better with a 8.5pv im gonna try a 9.5 should be the ticket the 8.5 is what i had handy it accelerates smoothly through the gears now just a bit of bog if u give it a stab of the throttle. I also was able to bring the pump shot back down just a quick change to the 35 squirter made the nuetral reving more repsonsive i'll start tuning more when it's time for test runs. Kev |
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| Author: | DusterIdiot [ Sun Jan 31, 2010 8:29 pm ] |
| Post subject: | Two things... |
1) Holley 9.5 Power valves are of the "hole" type, not the "picture window"... they just don't flow what you will need if you decide to drag race... you might just go for the 10.5 and call it good, so you don't have a lean out for other reasons... 2) The 270+ duration cam, isn't going to like idling at 700 rpm... by the time the throttle plates swing far enough to engage the transition slots then mains, you will be fighting a dead spot off idle, so move the idle speed to 800-850rpm and see if that helps a bit as well... -D.Idiot |
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| Author: | 1974duster kev [ Mon Feb 01, 2010 6:24 pm ] |
| Post subject: | |
hmm ok so go for the 10.5 then, ya that makes sense i still do have a bit of a buck from an off idle stab of the throttle but it seems to have a diference in power is blows the tires off if i dump it decently hard now off the line and pulls strong to well over 5000rpm but everything isn't 100% tuned yet so i'll figure it out once i can really romp on the motor. thanks for the tip on the pv and im curious what do you mean by the 9.5 pv is a different style? Thanks kev |
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| Author: | SV162 [ Mon Feb 01, 2010 7:26 pm ] |
| Post subject: | |
What vacuum have you got now with the new cam Kev? |
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