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Re: 340 not what I thought it would be...Any ideas?
[Re: Telvis]
#1642500
07/06/14 09:41 AM
07/06/14 09:41 AM
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Joined: Jan 2003
Posts: 5,446
Indiana
YO7_A66
master
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master
Joined: Jan 2003
Posts: 5,446
Indiana
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""2500 rpm stall TC/3:23 Sure Grip rear/255-60-15 tires in the rear.""
My stock stroke 340 in the last 13 years:
I have swapped out four carbs, two intakes, three cams, HP manifolds to TTi headers, three ignition systems, three torque converters, two different rear tire/rim sets.
For a street car, I have found the combination of the 340/2500/3:23/255 rear tires as your biggest mis-match. The 255's are a big tire to turn but I would keep them because as soon as you change your gear/converter, you will need them!
I believe that if you put your money into a good converter, your 3:23's "might" be ok. But I think that it is the combo of the 2500/3:23's that is keeping your off the line fun down.
Note: I run 3800/3:91/255 rear tires and I get instant tire spin off idle (no holding the brake) and also off of a rolling start. It is a fun street combo.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
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Re: 340 not what I thought it would be...Any ideas?
[Re: Telvis]
#1642501
07/06/14 10:29 AM
07/06/14 10:29 AM
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Joined: Sep 2003
Posts: 20,491
north of coder
moparx
"Butt Crack Bob"
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"Butt Crack Bob"
Joined: Sep 2003
Posts: 20,491
north of coder
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Quote:
Quote:
Does it have good throttle response? Are the secondaries opening on the carb?
I don't know... Have no reason to think they aren't. How do you know if they open? The throttle response seems fine. When I say the motor seems sluggish maybe that is the incorrect description. It just doesn't seem to have the torque I expected. It has no hesitation.
even if the secondaries are opening, are they opening the whole way ? as in : is the throttle cable adjusted properly ? you would be amazed at how often this happens.
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Re: 340 not what I thought it would be...Any ideas?
[Re: ScottSmith_Harms]
#1642502
07/06/14 10:38 AM
07/06/14 10:38 AM
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Joined: Jan 2003
Posts: 25,200
Upper Midwest
MoparforLife
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,200
Upper Midwest
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Quote:
Problem = 3:23 Sure Grip rear
Try some 3.55's or 3.91's, that'll wake it up
I agree and back the timing down to about 35 degrees. Most small blocks I have been around 35 degrees or less. My 360 in fact ET'd best at 32/34
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Re: 340 not what I thought it would be...Any ideas?
[Re: Telvis]
#1642503
07/06/14 10:48 AM
07/06/14 10:48 AM
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Joined: Jan 2003
Posts: 13,031
Benton, IL.
DaveRS23
Master of nothing...
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Master of nothing...
Joined: Jan 2003
Posts: 13,031
Benton, IL.
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Just as a test, you can take a small screw with it's nut and put in the secondary's slot so that the primary lever immediately opens the secondaries with the primaries. This will likely be too much, too soon if you open it up at low engine speed. But you will be able to tell as the engine revs up whether it runs better than before.
Again, this is just a test to see if you can tell a difference with the secondaries known to be opening.
Last edited by DaveRS23; 07/06/14 10:51 AM.
Master, again and still
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Re: 340 not what I thought it would be...Any ideas?
[Re: DaveRS23]
#1642504
07/06/14 07:53 PM
07/06/14 07:53 PM
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Joined: Sep 2013
Posts: 464
KY
Telvis
OP
mopar
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OP
mopar
Joined: Sep 2013
Posts: 464
KY
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I can get a 3:91 gear for a good deal. I just figured it would be no fun to drive above 50 mph. I don't a do a lot of interstate driving but I do drive at 60 or so quite a bit when I cruise. Is that going to be too low a gear?
That's King Weenie to you!
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Re: 340 not what I thought it would be...Any ideas?
[Re: jcc]
#1642509
07/06/14 10:43 PM
07/06/14 10:43 PM
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Joined: May 2005
Posts: 4,935
Florida
BDW
master
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master
Joined: May 2005
Posts: 4,935
Florida
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Quote:
I'm surprised with all the 255/3.23 theorists. I got a similiar mild built 360 with 3.55 and 305's and a tighter converter can't keep the rear tires stuck. Something in the OP's tune is off, I don't see a drive train issue, except the 255's are too narrow. 
Same here, pretty stock 340, had 3.55s, now have 3.73 and no problems spinning the tires from a dead stop, and still spinning as car is shifted into 2nd.
Auto with RMVB.
Something else going on, gears or TQ isn't your problem.
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Re: 340 not what I thought it would be...Any ideas?
[Re: BDW]
#1642510
07/06/14 11:38 PM
07/06/14 11:38 PM
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Joined: Jan 2003
Posts: 1,796
Windsor, ON, Canada
Diplomat360
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,796
Windsor, ON, Canada
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Quote:
Quote:
I'm surprised with all the 255/3.23 theorists. I got a similiar mild built 360 with 3.55 and 305's and a tighter converter can't keep the rear tires stuck. Something in the OP's tune is off, I don't see a drive train issue, except the 255's are too narrow.
Same here, pretty stock 340, had 3.55s, now have 3.73 and no problems spinning the tires from a dead stop, and still spinning as car is shifted into 2nd.
Auto with RMVB.
Something else going on, gears or TQ isn't your problem.
Well, for what it's worth, I am a bit on the other side of this 'argument'...360 build here, 165 PSI static compression, Hughes HE3834AL hydraulic flat tappet cam (238/244 dur, .536/.540 lift, 108 LSA), Perfomer RPM intake, ported heads, 2800 stall converter, 3.91 SG rear end and Nitto 275-60-15 tires...no tire spin AT ALL...well, sometimes maybe, but the Nittos grab like crazy...felt the motor was a tad weak in the lower RPM...moved to a Dynamic 3800 stall converter over the winter...in the car now, haven't tested it yet as I'm finishing up the sub-frame connectors install. All converter shops I talked to unanimously stated I had way too little converter for that cam...
Your cam is smaller, and depending on what tire you are running it should spin the wheels at least a tad...but ultimately it's about the combination.
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Re: 340 not what I thought it would be...Any ideas?
[Re: Diplomat360]
#1642511
07/07/14 12:57 AM
07/07/14 12:57 AM
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Joined: Sep 2004
Posts: 6,906
IL, Aurora
ademon
master
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master
Joined: Sep 2004
Posts: 6,906
IL, Aurora
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Quote:
Quote:
Quote:
I'm surprised with all the 255/3.23 theorists. I got a similiar mild built 360 with 3.55 and 305's and a tighter converter can't keep the rear tires stuck. Something in the OP's tune is off, I don't see a drive train issue, except the 255's are too narrow.
Same here, pretty stock 340, had 3.55s, now have 3.73 and no problems spinning the tires from a dead stop, and still spinning as car is shifted into 2nd.
Auto with RMVB.
Something else going on, gears or TQ isn't your problem.
Well, for what it's worth, I am a bit on the other side of this 'argument'...360 build here, 165 PSI static compression, Hughes HE3834AL hydraulic flat tappet cam (238/244 dur, .536/.540 lift, 108 LSA), Perfomer RPM intake, ported heads, 2800 stall converter, 3.91 SG rear end and Nitto 275-60-15 tires...no tire spin AT ALL...well, sometimes maybe, but the Nittos grab like crazy...felt the motor was a tad weak in the lower RPM...moved to a Dynamic 3800 stall converter over the winter...in the car now, haven't tested it yet as I'm finishing up the sub-frame connectors install. All converter shops I talked to unanimously stated I had way too little converter for that cam...
Your cam is smaller, and depending on what tire you are running it should spin the wheels at least a tad...but ultimately it's about the combination.
my 360 is close to yours but running a mechanical 6 pack , 3.55, with the same nitto tires. 4,400 dynamic stall. On blacktop bringing it to 3,000 then flooring it roasts the tires all the way to the rev limit and all the way through first into second, on concrete it will lay a good 25' patch.
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