Stall speed question

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DERICKS

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CLINTON TOWNSHIP,MI
I need your advice or experiences with stall speed on a combination like mine. The converter flashes 3600 at best on a hot day and the car feels a little lazy to me. I was told by Sean at Dynamic that he could get it to flash 4200-4400 after reworking it. Is that enough for my combo or do I need to go to an 8 inch converter at 4500+?? Thanks

Car 1973 Duster
Weight 3250 with driver
Gear ratio 4.30
Tire diameter 28
RPM through trap 6100
1.63 sixty foot best ever usually 1.70's
MPH through traps 111.87
ET 11.99

Engine CID 346
Head Type factory 308 casting
Valve size 2.02/1.60
Head Work none other than 2.02 intake valve
Cam Manufacturer Mopar performance
Cam specs at 50 .248
Carb type and size Holley HP 750
PV Rating 3.5/none
Jet sizes 78/82
Plug number and brand champion RN9YC
Intake Manifold Type Edelbrock Torker II
Piston Make TRW replacements
Compression Ratio 10.5

Trans type 904
Trans Mods T/A reverse manual valve body
Convertor type Dynamic 9 1/2
Convertor stall 3600
Trans Brake none

Drive shaft stock or aftermarket dynatech

Initial timing 36
Total timing 36
Total advance at what RPM locked out

Rear end type 8 3/4 with back brace, spool, mark williams caps, rifle drilled mark williams axles
 
What cam did you use and where was it degreed? You might pick up some bottom end by advancing it. That is if you put it in straight up. Alot easier and cheaper than pulling a trans plus paying to get the convertor reworked.

don
 
Wow, I was just looking at your pictures in your garage and I realized that the 68 GTX that was parked next to you was my old car. Was that taken at Lapeer? I sold it in 1985 and i think its gone through about 6 or 7 owners since. I last saw it at Milan about 2 years ago. Lots of great memories from that car.

don
 
Have you had your car chassis dyno'd yet? Find out at what rpm your torque peak is and find a torque converter with a matching stall speed.
 
Got a couple of questions for ya. I'm unfamiliar with your HP 750 Holley spec is that a DP'r or vacuum secondary and are you running a 4 hole spacer with that single plane manifold? Also is your initial timing actually at 36 degrees. Also, when you say sorta lazy is that off the line or midrange?
 
dusterdon said:
What cam did you use and where was it degreed? You might pick up some bottom end by advancing it. That is if you put it in straight up. Alot easier and cheaper than pulling a trans plus paying to get the convertor reworked.

don
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Hey Don,
I used the MP 292/.508 that has a 108 centerline and I installed it advanced at 104. Yep that picture was at Lapeer last year, my buddy Marc bought the GTX a year or so ago. It is a very cool car and he enjoys the heck out of it.
 
demon seed said:
Got a couple of questions for ya. I'm unfamiliar with your HP 750 Holley spec is that a DP'r or vacuum secondary and are you running a 4 hole spacer with that single plane manifold? Also is your initial timing actually at 36 degrees. Also, when you say sorta lazy is that off the line or midrange?
Click to expand...

The 750 hp I have is a double pumper, the spacer setup is a 4 hole phenolic 1inch stacked on top of a open 1 inch phenolic. The manifold is a single plane Edelbrock torquer II. The intial timing is 36 degree's and is locked out at that spec. The car comes out with a little tire spin then picks up fast in the middle of first gear. I'll post a video to better explain what I'm talking about.

http://media.putfile.com/Duster-Launch
 
Intitial timing 36, total timing 36 ?!? Are you really running a locked distributor? While 36 degrees might be reasonable for your combo at high RPM, thats a pretty stiff amount down low. How do you start it? Rolling and bucking down a long steep hill? Can it idle with 36 degrees advance? If thats the case, I wonder if you are a bit over advanced at low RPM.

Your combo looks to me like "a bit lazy" is a somewhat relative term; seems pretty well balanced. Bloody huge cam for those heads perhaps. Is your 10.5 compression calculated or measured? Exhaust system (header primary length)? Are you traction limited at all? Ever consider W-2 heads?
 
DERICKS said:
The 750 hp I have is a double pumper, the spacer setup is a 4 hole phenolic 1inch stacked on top of a open 1 inch phenolic. The manifold is a single plane Edelbrock torquer II. The intial timing is 36 degree's and is locked out at that spec. The car comes out with a little tire spin then picks up fast in the middle of first gear. I'll post a video to better explain what I'm talking about.

http://media.putfile.com/Duster-Launch
Click to expand...

That's good, I was concerned that you were running a vacuum secondary carb with that single plane and if you weren't running a 1" 4 hole I'd recommend it for the bottom end. My only other concern is that by running your ignition timing so far advanced at low RPM, you may be experiencing detonation off the line which will hold the engine back and it won't reach full RPM as fast as it should. Have you tried running your initial at lets say 18 deg and having it at full advance at 2000-2500 RPM. The reason I say this is you're running the same intake, cam, comp. ratio and converter as my 383 (not sure about your headers) and my combo pulls really hard from the second you floor it till the end of the quarter at 6000RPM. (my gears are 3.91). You may want to try removing the 1" open spacer and just go with the 4 hole which may increase your fuel air charge velocity, at low RPM, and also help the bottom end.
 
C130 Chief said:
Ever consider W-2 heads?
Click to expand...

derrick had a BAD little SB with W-2 heads before this motor but built this motor for a nice street cruizer.....i really dont think he'll be putting a set of W-2's on this motor..

derrick,
i think you and i need to swap rears...you need MORE gear with your 340 and i need LESS gear for my 360!!! :headbang:
 
C130 Chief said:
Intitial timing 36, total timing 36 ?!? Are you really running a locked distributor? While 36 degrees might be reasonable for your combo at high RPM, thats a pretty stiff amount down low. How do you start it? Rolling and bucking down a long steep hill? Can it idle with 36 degrees advance? If thats the case, I wonder if you are a bit over advanced at low RPM.

Your combo looks to me like "a bit lazy" is a somewhat relative term; seems pretty well balanced. Bloody huge cam for those heads perhaps. Is your 10.5 compression calculated or measured? Exhaust system (header primary length)? Are you traction limited at all? Ever consider W-2 heads?
Click to expand...

Yep, the distributor is locked...I just never changed it from my old engine. I plugged it in and it ran so I left it. It starts very easy witha high torque starter and idles arond 850rpm in gear. The comp is calculated and the cam was a freebie so I went with it...i had no money to port the heads either. The headers are Hooker 1 5/8 tube witha three inch exhaust (also a left over) that exits before the axle.
 
demon seed said:
That's good, I was concerned that you were running a vacuum secondary carb with that single plane and if you weren't running a 1" 4 hole I'd recommend it for the bottom end. My only other concern is that by running your ignition timing so far advanced at low RPM, you may be experiencing detonation off the line which will hold the engine back and it won't reach full RPM as fast as it should. Have you tried running your initial at lets say 18 deg and having it at full advance at 2000-2500 RPM. The reason I say this is you're running the same intake, cam, comp. ratio and converter as my 383 (not sure about your headers) and my combo pulls really hard from the second you floor it till the end of the quarter at 6000RPM. (my gears are 3.91). You may want to try removing the 1" open spacer and just go with the 4 hole which may increase your fuel air charge velocity, at low RPM, and also help the bottom end.
Click to expand...


I see what you're saying about the spacer and I may try pulling that next. My question is if my converter flashes 3600rpm and my timing is 18 degree's set to come in at 2000-2500rpm isnt it really at 36 degree's anyways when the car launches???
 
mikesduster said:
derrick had a BAD little SB with W-2 heads before this motor but built this motor for a nice street cruizer.....i really dont think he'll be putting a set of W-2's on this motor..

derrick,
i think you and i need to swap rears...you need MORE gear with your 340 and i need LESS gear for my 360!!! :headbang:
Click to expand...


Hey Mike,
No more gear for me buddy I do too much driving and was even considering going to 3.91's. I shift at 6000rpm and go through the traps at the same so I think the gear is about right. I'm still on a really tight budget so changes are going to be minimal.
 
DERICKS said:
I see what you're saying about the spacer and I may try pulling that next. My question is if my converter flashes 3600rpm and my timing is 18 degree's set to come in at 2000-2500rpm isnt it really at 36 degree's anyways when the car launches???
Click to expand...

Derrick you're absolutely right, if your engine lives between 3000 and 6000 RPM, running the initial timing lower doesn't really matter. The problem is that if you do any driving lower than 3000 and the engine is in detonation you'll damage pistons, rings or valve faces which would be a bad thing. That's primarily where I was coming from. Also the condition people call detonation is sometimes the sound the engine makes when it suffers from pre-ignition. Pre-ignition can be caused by timing advancing to quickly for the RPM, hotspots like glowing carbon or running gas with to low of an anti knock number (octane rating) among other things. Let me try explaining this a different way. If the engine is in detonation as you pull up to the line the combustion temperatures are sky rocketing, the effects of pre-ignition can be self propagating (snowball rolling down a hill). Now 30 seconds later the light turns green and you floor it and the engine is not in it's happy place for those first few seconds. That will effect performance.

I'm getting long winded cause it's bedtime for bonzo, Goodnight.
 
Hey Demon seed,
I see where you're coming from on the detonation thing, I guess I was just locked on the strip part of it and not thinking about daily driving. I guess the best I can do is watch the plugs and make sure I get good gas. I'm not even sure I have the parts to put my MSD back to having a swing in timing! LOL Its been a while since it was changed with the old race engine I had a few years back. Thanks for the heads up.
 
ramcharger said:
Um, look at the third reply.
Click to expand...
Yep, I read it and its a good suggestion. My problem is a very tight budget for changes. By the time i spend several hundred bucks on dyno time i will have no money to make the change it would suggest....not what i was looking for. I was hoping to find someone who has or has had a similar combo that could add some insight. thanks
 
being a 340,you really need MORE stall.....even a 8" converter which im running and it flashes at 4200...thats where you need to be.

my 2 cents.
 
Derick all I can tell you is I bought 3 convertors from Sean at Dynamic and we are all very happy with them. I just got my 63 out for the first time and only got 1/8 mile passes but on the original leaf springs and air shocks it had a 1.58 best 60 out of the 3 passes I got. Its a Dynamic 9.5 street/strip convertor and they hit the nail right on the head as it makes my iron head 10.0 comp 440 launch nicely at 3640 lbs. My sons Dart ran the same 1/8 mile et as me that day and he has run 11.50's on good days and his car 60's in the low 1.60's with a 1.61 best. It wont hurt to let them at Dynamic go over the convertor if thats what you decide. I wont race my 63 again until I put a 6 point roll bar in it as it leaves so hard with that convertor I dont want to twist on the body to much. I would think your Duster should 60 in the 1.65 to 1.70 with ease all the time. Ron
 
Hey Mike I think I will just stick with Dynamic, they have always made me happy with my converters one way or another. I think you are right Ron....YOUR car does hook like mad with that 9.5 converter! I was thinking 4200-4400 should be about the best I can get with my current converter. My car is stuck in the 12.00's 60 footing on the mid 1.70's on M/T Sportsman Pro's. I hope my switch to the ET Streets and loosening up the converter about 800 rpm should put me in the 11.60-11.70 range 60 footing in the mid 1.60's....or better! Hey I can wish cant I?? LOL
 
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