Car seems "lazy". Where to start?
#1670040
09/11/14 03:55 AM
09/11/14 03:55 AM
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Joined: Feb 2003
Posts: 1,730 Red Deer, Alberta
bill_greenwood
OP
top fuel
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OP
top fuel
Joined: Feb 2003
Posts: 1,730
Red Deer, Alberta
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Well, once we got the camshaft grooved and back in, I have been to the new 1/8 track close to home. The starting line is a little green yet, so the 60's have been soft, but the addition of the roller and intake change don't appear to have resulted in any more power. My best posses have been 1.63/7.38/92.5. My 11.40 runs at Castrol are all low 1.50 in the 60, with the 1/8 coming in at 7.20 and 93-95 mph. Even factoring in the soft 60, I don't appear to be making any more power than I did with my pedestrian little MP 528 solid. The new cam is the Comp 577/308 roller and I switched up to single plane M1 as well. Any ideas where to look first? Would the cam and intake change necessitate more jet? FWIW, I've been going rounds. 5 rounds to win in August, six rounds to lose going in to the semi's this past Saturday. More luck than skill, mind you. PS. Only in Alberta will you see a fairly new Bentley bracket racing in the street classes.
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Re: Car seems "lazy". Where to start?
[Re: bill_greenwood]
#1670042
09/11/14 09:33 AM
09/11/14 09:33 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Whats the LSA on the cam and what did you install it at.. whats the ignition timing at and whats the stall... yes it might need jet changes
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Re: Car seems "lazy". Where to start?
[Re: MR_P_BODY]
#1670043
09/12/14 03:37 AM
09/12/14 03:37 AM
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Joined: Feb 2003
Posts: 1,730 Red Deer, Alberta
bill_greenwood
OP
top fuel
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OP
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Joined: Feb 2003
Posts: 1,730
Red Deer, Alberta
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Cam is 106 centerline, 110 lobe separation, installed straight up. I run 36 deg total timing. Converter is a TCS 9" that flashes to 4700-5000. In replaying the Go-Pro, what I see is a bit of a soft bog just after the hit, probably 40-50 feet out. I bring the motor up to about 2000 on the converter, so I'm wondering if I need to go to a smaller shooter to carry the car further out, or change the pump cam to bring the pump shot in later. I haven't tried jetting yet, as our track days have been quite the thrash. I had jetted it a bit on the fat side for the old cam/intake, so it could be off a bit. 1/8 mile racing puts a ton of cars through real quick, and a charging glitch has cropped up that has prevented any tweaking between rounds. I've also switched from VP C-12 to Sunoco 110, but I can't think that's much of a difference, or am I dead wrong? Part of the soft 60 is due to the soft hook. A couple of my passes had a ton of wheelspin, but there were a few that also hook sort of okay. With the old cam and intake, the car got quicker in the 60' and became more consistent with the switch from a 4000 converter to a 4700. But, it slowed down a full tenth overall. Switching from 4.88's to 5.13's made it dead nuts consistent, but lost a little more ET while getting quicker in the 60. The problem at that point was the regular pushrod or lifter loss. I had good 5/16 pushrods, and the standard Mopar Perf. lifters. Occasionally I would either pop a pushrod at about the 1200' mark, or have a pushrod go through the lifter disc. I switched to the roller after a new set of lifters wiped the cam. Given that it never sees less than 5000 rpm all the way down the track, I think the fatter cam was a good move, but it needs some tweaking to get woken up.
Last edited by bill_greenwood; 09/12/14 03:53 AM.
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Re: Car seems "lazy". Where to start?
[Re: bill_greenwood]
#1670045
09/12/14 12:04 PM
09/12/14 12:04 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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You said you put it in straight up... did you degree this and whats the number... its a 110* cam and they suggest it in at 106 which is 4* advanced but what did you degree it to... you need to look into your bog first thing
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Re: Car seems "lazy". Where to start?
[Re: bill_greenwood]
#1670046
09/13/14 12:50 AM
09/13/14 12:50 AM
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Joined: Jul 2013
Posts: 561 USA
B3RE
mopar
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mopar
Joined: Jul 2013
Posts: 561
USA
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Quote:
With the old cam and intake, the car got quicker in the 60' and became more consistent with the switch from a 4000 converter to a 4700. But, it slowed down a full tenth overall. Switching from 4.88's to 5.13's made it dead nuts consistent, but lost a little more ET while getting quicker in the 60. The problem at that point was the regular pushrod or lifter loss. I had good 5/16 pushrods, and the standard Mopar Perf. lifters. Occasionally I would either pop a pushrod at about the 1200' mark, or have a pushrod go through the lifter disc. I switched to the roller after a new set of lifters wiped the cam. Given that it never sees less than 5000 rpm all the way down the track,
If you are destroying lifters, pushrods, and camshafts, then you have valvetrain issues. It also explains why you are losing et when going to lower gears. BTW, roller cams aren't immune to valvetrain issues. Just imagine needle bearings being scattered through the motor when a lifter fails from being pounded. Ouch.
Mike Beachel
I didn't write the rules of math nor create the laws of physics, I am just bound by them.
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