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#2520851 - 07/11/18 11:28 PM Fluttering in high gear
Derrick Payne Offline
member

Registered: 09/21/16
Posts: 7
Loc: Mt.Vernon,KY
I put a big block in my duster that the motor had been setting for a few years and it’s goes to fluttering at higher rpm’s in high gear I was wondering if the value springs would be the problem

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#2520868 - 07/12/18 12:04 AM Re: Fluttering in high gear [Re: Derrick Payne]
StealthWedge67 Offline
master

Registered: 07/19/06
Posts: 4121
Loc: Puyallup, WA
If it only does it in high gear, I’d look at the ignition system 1st. Fuel delivery 2nd. My experience is that Valve springs will create more of an rpm limit feel, with a backfiring condition.
twocents
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#2520890 - 07/12/18 02:05 AM Re: Fluttering in high gear [Re: Derrick Payne]
skrews Offline
enthusiast

Registered: 07/28/12
Posts: 303
Loc: Washington
^ Yep valve spring will show up at same RPM in every gear, at least has been my experience.

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#2520897 - 07/12/18 03:10 AM Re: Fluttering in high gear [Re: Derrick Payne]
Cab_Burge Offline
I Win

Registered: 08/23/03
Posts: 31224
Loc: Bend,OR USA
Originally Posted By Derrick Payne
I put a big block in my duster that the motor had been setting for a few years and it’s goes to fluttering at higher rpm’s in high gear I was wondering if the value springs would be the problem

is this at wide open throttle or part throttle cruising?
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#2521087 - 07/12/18 02:05 PM Re: Fluttering in high gear [Re: Cab_Burge]
Derrick Payne Offline
member

Registered: 09/21/16
Posts: 7
Loc: Mt.Vernon,KY
Wide open

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#2521089 - 07/12/18 02:14 PM Re: Fluttering in high gear [Re: Derrick Payne]
Derrick Payne Offline
member

Registered: 09/21/16
Posts: 7
Loc: Mt.Vernon,KY
It’s got a new fuel system, plugs and plug wires, distributor, took the carb and msd ignition off another car know nothing is wrong with them put a crank trigger on it and nothing so far has helped it.
Does good 1st to 2nd shift, does it sometimes in the higher rpm’s in 2nd, but always does it in 3rd I shift on 6600 just goes to about 6000 in 3rd and levels off put a little bit then falls back and started pulling again it ain’t a missing more like fluttering or surging

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#2521097 - 07/12/18 02:26 PM Re: Fluttering in high gear [Re: Derrick Payne]
an8sec70cuda Offline
I Live Here

Registered: 01/19/03
Posts: 10822
Loc: Marion, South Carolina [><]
Sure sounds like a fuel issue. Do you have a fuel pressure gauge you can see going down the track?
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'70 hemicuda...8.91 at 150.5 mph street car...Mopar Action feature Dec. '14
'69 road runner 446" w/ Indy SRs
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'71 Demon 340 resto project
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'16 Grand Caravan SXT...baby hauler

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#2521149 - 07/12/18 05:06 PM Re: Fluttering in high gear [Re: an8sec70cuda]
Derrick Payne Offline
member

Registered: 09/21/16
Posts: 7
Loc: Mt.Vernon,KY
Running two new Holley black fuel pumps have the presure from 7lbs to 15 and no difference don’t have the gauge where I can watch it down track though

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#2521226 - 07/12/18 08:10 PM Re: Fluttering in high gear [Re: Derrick Payne]
Cab_Burge Offline
I Win

Registered: 08/23/03
Posts: 31224
Loc: Bend,OR USA
A sure fire way to test the fuel system for adequate fuel delivery is to jet the carb. up one or two steps at a time until the 1/4 MPH slows down, if you can't do that you don't have enough fuel delivery scope
This is a very common problem on our Mopar production muscle cars with stock fuel pickups in the tank and stock fuel lines from the tank to the front of the car scope
I would set the pressure between 7.5 and 9.5 lbs. with a Holley carb.(not above 7.5 lbs high on a Carter or Eddy carb tsk) with .110 needles and seats and jet it up until you find out what you need to know up scope
IHTHs thumbs


Edited by Cab_Burge (07/12/18 08:10 PM)
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Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

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#2521334 - 07/13/18 02:29 AM Re: Fluttering in high gear [Re: Derrick Payne]
Dave Hall Offline
top fuel

Registered: 01/21/08
Posts: 1956
Loc: Cotati, CA
Sounds like it may be lean. It has the most load on it when you say the problem is happening. Check that your plug gap isn't too wide. Say .040 max.

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#2521434 - 07/13/18 11:14 AM Re: Fluttering in high gear [Re: Derrick Payne]
FurryStump Offline
master

Registered: 10/15/04
Posts: 2513
Loc: Connecticut
What lifter? Hyd/solId?
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