Re: Finally got out to the track last night!!...
[Re: Brian Hafliger]
#1052067
08/14/11 10:27 AM
08/14/11 10:27 AM
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If it bogged you might need more pump shot???
pump shot as in squirter, or as in pump cam?
its got 35 squirters in it right now, primary and secondary. 3.5PV and 75 primary jet, 76 secondary jet. Used to have a 78 secondary in it, but it was running quite a bit richer with that in it. Once I get some solid AFR numbers I think I will have a better direction for jetting
Try a 4.5 PV, 74P and 80S. Then try a Blue pump cam and .031 squirters. Make sure you adjust the pump arms. Blue cam in the front and rear! Make sure your mixture screws are about 1 1/2 to 2 turns out even if it idles a bit rich. That helps your throttle transition out also. Looks good!!
Thanks for the advice Brian...is this a jetting combination that you have done on similar builds to mine? That jetting is actually close to what I was going to try again when rejetting (stock was 75p, 80s). Right now my idle screws are about 1/2 to 1 turn out respectively since that was where the best idle and highest vacuum was..should I still try and back them out more even if it compromises idle quality? Or will the different jetting, pump cam, and pv allow it to idle ok with 1.5-2 turns out?
I don't know much about pump cams, but what exactly do they do, and when tuning with them, what do they change exactly? Thanks again as usual..like i said before, I am very happy with the way this engine works, and I think I can hit a low 12 with further tuning, which I will be extatic about considering how little I have into this motor
The pump cam is responsible for the volume/time the squirter sees. Trust me, get 2 blue cams, and go back to .031 squirts. Go up to 4.5 PV, and set the mix screws at 1 1/2 for now. Yes it will be a tad rich, that's the cam and that's OK. Very nice looking car and very good for a 9:1 360 4 row!!
sweet, will do Brian! Gonna get some of those secondary jet extensions in there as well (Can't believe I forgot about those things)
Yea, Im pretty damn happy with how its running for such a simple low compression engine....thanks again!
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Re: Finally got out to the track last night!!...
[Re: 6bblRoadrunner]
#1052068
08/14/11 10:29 AM
08/14/11 10:29 AM
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First off...good first outing. My opinion is that you need to increase your launch rpm (I ran into the same issue early on with my 4spd Demon). Like Mr P stated the small block doesn't make a lot of torque, so it needs rpm. You've stated that you have a 2-step in the car so I would keep increasing launch rpm (at the time I was tuning I would go up in increments of 400), then back off when your '60s start going the wrong way. The reason I say this is that (I'm assuming your leaving with the pedal on the floor) you've used your pump shots. The video camera is a great tuning aid for this. I found that what I thought was a clean leave still had a slight bog when reviewing the video. Keep testing...you'll get it.
will do. Question for ya- when you used a two step, or if you powershifted, did you get fire coming out of the exhaust? I am getting that and im not sure if thats normal or if its something i should be worried about
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Re: Finally got out to the track last night!!...
[Re: mshred]
#1052070
08/14/11 12:59 PM
08/14/11 12:59 PM
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Joined: Jan 2003
Posts: 27,421 Balt. Md
383man
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Nice car and great first outing ! Tune tune tune and then some. You will get tons of advise for tuning but the best I can tell you is make one change at a time and write down what changes you made. Believe me its easy sometimes to forget what made it faster or slower and its easy to forget jet sizes as I know that well. Thats why I like to even write down what size jets I put in. As for launching I agree with some here. I used to bracket race a 340 Dart back in the 80's that ran a best of 11.92 and I had it very consistent for a stick car. I always left the same way every run. That was as soon as I saw even the flicker of the first yellow lite I would zing it up to about 5 or 6K. Then when the last yellow was coming on (or when I wanted to launch) I would floorboard it and pop the clutch. And I mean I would slam it to the floor and hold it there thru the 1/4 mile. As long as you have enough gear it will take it and if it hooks good you will have a great launch. My feeling was I was there to race it and race it hard so I ran it as hard as I could and if it breaks then so be it as I would fix what broke and beef it up. To me thats the only was to launch a stick car.........slam the throttle on the floor and let it rip. Good luck with that cool looking and running Mopar and I bet you hit the 11's soon enough. Ron
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Re: Finally got out to the track last night!!...
[Re: MR_P_BODY]
#1052072
08/14/11 01:53 PM
08/14/11 01:53 PM
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Joined: May 2009
Posts: 511 Temperance, MI
68 HEMI GTS
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i always like watching a old school stick car beat up on modern muscle!!
68 Dart GTS "HEMI" 10.30 @ 131 pump gas street car 3780# 69 Roadrunner 511 six pack 10.92 drive to track street car
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Re: Finally got out to the track last night!!...
[Re: 6bblRoadrunner]
#1052073
08/14/11 02:59 PM
08/14/11 02:59 PM
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Question for ya- when you used a two step, or if you powershifted, did you get fire coming out of the exhaust?
Not that I was aware of...never saw it on the video's. Maybe you're hitting the rev limiter when you shift??? I did hit the high side limiter when it was only set 200rpm above my shift points (I run an MSD Digital6). I've increased it to 400rpm above shift points and don't hear any misfires when I power shift.
I have my shift light set at 5900, so im probably shifting around 6 or 61, limiter set to 6400 i believe. Its alot worse on the launch since as soon as that first amber lights up im sitting on that two step and its popping away
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Re: Finally got out to the track last night!!...
[Re: 383man]
#1052074
08/14/11 03:02 PM
08/14/11 03:02 PM
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Nice car and great first outing ! Tune tune tune and then some. You will get tons of advise for tuning but the best I can tell you is make one change at a time and write down what changes you made. Believe me its easy sometimes to forget what made it faster or slower and its easy to forget jet sizes as I know that well. Thats why I like to even write down what size jets I put in.
As for launching I agree with some here. I used to bracket race a 340 Dart back in the 80's that ran a best of 11.92 and I had it very consistent for a stick car. I always left the same way every run. That was as soon as I saw even the flicker of the first yellow lite I would zing it up to about 5 or 6K. Then when the last yellow was coming on (or when I wanted to launch) I would floorboard it and pop the clutch. And I mean I would slam it to the floor and hold it there thru the 1/4 mile. As long as you have enough gear it will take it and if it hooks good you will have a great launch. My feeling was I was there to race it and race it hard so I ran it as hard as I could and if it breaks then so be it as I would fix what broke and beef it up. To me thats the only was to launch a stick car.........slam the throttle on the floor and let it rip. Good luck with that cool looking and running Mopar and I bet you hit the 11's soon enough. Ron
Thanks! I do have a log book going, I got the girlfriend trained about what im talking about and she's writing it down neatly for me instead of my rushed chicken scratch lol...I have the whole carb setup written down in that book
As far as my launchs go, im going to post another video, but in car, so you guys can see and hear the bog im talking about. As soon as that first amber glows my foot is matted on the throttle against the two step, when its green i dump the clutch and let go of the two step button on the shifter at the exact same time. I have beefed up the car for abuse for this year since last year I broke everything...But i love racing a stick, nothing funner than banging every gear with my right foot down the whole time
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Re: Finally got out to the track last night!!...
[Re: MR_P_BODY]
#1052075
08/14/11 03:03 PM
08/14/11 03:03 PM
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Question for ya- when you used a two step, or if you powershifted, did you get fire coming out of the exhaust? I am getting that and im not sure if thats normal or if its something i should be worried about
How do you have your 2 step button/switch hooked up... if you have it on the clutch you could be engaging the 2 step when you hit the clutch
no I have it on the shifter with a button...i've been told by some that the fire is normal because its popping unburnt fuel? but i thought I would ask here, since its quite the lightshow under the car when im using it lol
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Re: Finally got out to the track last night!!...
[Re: 68 HEMI GTS]
#1052076
08/14/11 03:05 PM
08/14/11 03:05 PM
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i always like watching a old school stick car beat up on modern muscle!!
yea, tell me about it, felt good! I raced a Z06 vette, which I knew would eat me, but he only caught me half track (mph at 120, if he hooked it would be a monster)
That new chally i raced in my fastest pass was funny....in the staging lanes the guy starts saying that my 60's were slow, how is old capri ran 1.30' 60" foots in the 12's, blah blah blah...then I took his SRT8 challenger out like nothing, and he didnt say much after
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Re: Finally got out to the track last night!!...
[Re: mshred]
#1052078
08/14/11 03:26 PM
08/14/11 03:26 PM
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yea, i know, but what can you do right? I wanted to go, and it was the only time I could. Today is an OSCA weekend, with qualifying starting at around 2, so i figured i'd get more runs in on a non even night than an event day. Going back next Friday probably, and possibly staying over for the saturday test and tune as well
Cool I may come down Saturday for some test and tune too!
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Re: Finally got out to the track last night!!...
[Re: MR_P_BODY]
#1052079
08/14/11 03:40 PM
08/14/11 03:40 PM
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when its green i dump the clutch and let go of the two step button on the shifter at the exact same time. I have beefed up the car for abuse for this year since last year I broke everything...But i love racing a stick, nothing funner than banging every gear with my right foot down the whole time
Ok I see you have the button on the shifter so that wouldnt be the issue with the clutch... its common for the chips in the 2 step to be off on the RPM (200-400 rpm off) so try putting in a higher chip
Hey Mr. P, Ive checked the chip, its definitely working ok as I saw it sitting on 5k when I was at the line...im going to upload a video right of the inside and of the car hitting the tire
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Re: Finally got out to the track last night!!...
[Re: RobX4406]
#1052083
08/14/11 04:19 PM
08/14/11 04:19 PM
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If you have it matted when launching, squirters and pump cams won't help you.
If it's a bit lean up top, when you dump the clutch and load the engine off the two step, I bet it's spiking even leaner. Jet it up and see how it reacts. I'd try the jetting Brian suggested. Also look up the factory jetting for the carb and note the jet stagger front to rear and try to run that stagger, or real close, if no PV in rear.
You have plenty of stuff to try. Personally, I'd start with getting the carb jetted for max MPH, then start tweeking with other stuff.
Yes you need a notched float to run those jet extensions.
It's all trial and error.
The stock jetting was 75 primary, 80 secondary..Brian's suggestion was 74 primary, 80 secondary, so i think i will try that and see what happens since it will be a touch leaner than the stock jetting, which was slightly rich on my last motor. I am using a power valve, but I was wondering what would be the difference of benefit from going to the 4.5 pv opposed to the 3.5 i have in it now.
I will be ordering the jet extensions tommorow along with the floats. Thanks!
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