Another guess my SB 340 et 1/4 mile :)

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340Duster247

340Duster247

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Ok everyone here are the specs.

1971 plymouth duster
340 .40 over balanced.
Holley 750 street hp
Eddy air gap intake
Eddy rpm performer heads
Comp .497/.287 cam
Tti headers
Msd digital 6 W/2step
Milodon pan

100 shot NOS nitrous super power shot

727 trans
TCI 3800 stall torque converter
8 3/4 rear with 4.30s

315/60/15 MT drag radials

I don't mean to repost but made some changes and would love to here your guys opinions.
 
Well.....here's what I wrote in June.........:D.

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"The converter will probably be the limiting factor, but how early you're willing to apply the juice may counteract it some. Just get her out there and make some passes. The info you'll accumulate will be priceless and help guide you to where you need to go with adjustments...

Honestly, with the fresh combo that you have, if you run some 12's after 2/3 passes and bring it home in one piece, i'd be thrilled with the intial outing.

Good luck, and keep us posted as you finish the build...:thumleft:"
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Looks like you have a little more converter now, but i'll stick with my initial thoughts. Lets face it, if you go faster, that a good thing.....

Good Luck finally getting her out there. Be safe & have fun!!!
 
First pass,12:60/12:80's,if your tune is close. Weight ,needs some info. Spray,low mid 11's,applied right.
 
Thanks OldMan!!
Yah we are trying to get her all dialed up right now. That 2800 just was not cutting it. Wqs just loading up the engine. Spoke with my engine builder, and the new convertor was a must. Haven't even driven the car yet ( other then down the back alley). The converter is still on order. Ill keep everyone updated

I also updated the gears to 4.30s :D
 
On spray I would love to see mid 11.s. will be happy with mid-low 12s on motor.
Gonna look into caltracs when the wallet gets a lil less stressed
 
I'm not sure on weight. Pretty much stock. But the aluminum engine parts. Battery relocated to trunk. And centerline qualifier light weight wheels
 
Haha thanks bomber. It's all new to me. Gonna start with a 100 shot. Running a fuel pressure safety switch, and window switch.
If you have any tips, I'm all ears.
Thanks!!
 
I'm curious as to your target date to get to the track? Before winter sets in? And if so, how many opportunities will you have?
 
340Duster247 said:
Wqs just loading up the engine. Spoke with my engine builder, and the new convertor was a must.
Click to expand...

Fix the ignition system... initial, total, curve because that should not be loading up.

If you don't know what the initial timing is and only know total, that's likely part of the problem!

If it hooks and runs well, it should go 12.00 on engine and 11.00 on juice.
 
Yah we are having tons of trouble with vacume and running stupidly rich!!!! We were almost ready to drill holes in the throttle butterfly plates. Changed power valve. Looked everywhere for vacume leaks. (When I turn idle mix screws all the way in. Engine Dosent die). Idle from park to drive was big drop and seem to have mind of its own.
We've tried the intital timing at many diffent degrees with the same outcome. This cam is rumored to love lots of intial timing.
Was only pulling 5-7" vacume at 1000 rpm. Total from 34-36.
Must admit have not changed stock distributer yet. :s that's getting changed very soon
Once new converter is in gonna get my engine builders expert in to dial her in.

I'm still learning lots about getting her dialed in and that's what's great about this site and all you guys. So bare with me if I'm all over the place.

I've had a couple old mopars before but both very mild small blocks. And This is my first time with more radical cam, stall ect. So I got a lot more to learn.

If you have any ideas where I should plant the initial timing please post our thoughts.
 
340Duster247 said:
Sorry boys won't be running her this year.
Click to expand...

I know your itching to get out there, but at least the time spent getting ready isn't a crazy rush. I really like your combo. It's just mild enough that some spray can make a huge difference. Since you'll have multiple times to get out in the spring, sounding like the old guy i am....lol, i'd probably get her dialed in without the bottle first, then let the juice fly. That's just me though. Can't wait til you get out though. If I hit the lottery, i'm flyin up to watch you run that bad boy...:D.
 
340Duster247 said:
Yah we are having tons of trouble with vacume and running stupidly rich!!!! We were almost ready to drill holes in the throttle butterfly plates. Changed power valve. Looked everywhere for vacume leaks. (When I turn idle mix screws all the way in. Engine Dosent die). Idle from park to drive was big drop and seem to have mind of its own.
We've tried the intital timing at many diffent degrees with the same outcome. Was only pulling 5-7" vacume at 1000 rpm. Total from 34-36.
Must admit have not changed stock distributer yet. :s that's getting changed very soon
Once new converter is in gonna get my engine builders expert in to dial her in.

I'm still learning lots about getting her dialed in and that's what's great about this site and all you guys. So bare with me if I'm all over the place.

I've had a couple old mopar before but both very mild small blocks. And This is my first time with more radical cam, stall ect. So I got a lot more to learn.
Click to expand...


If you have the stock distributor and it has not be recurved or modified...then the initial timing is no where correct.....

to get it to idle..you are opening the throttle blades to allow air into engine..that is why the idle screws do not do ****...

yeah...those new converters will solve all those problems...NOT...
 
Stock distributor? Really?

If you didn't have at least 18* on it, you aren't even close. That thing won't idle worth a darn with the total timing method and a stock distributor. The big rpm drop is the first clue, idle mix screws not killing it is second... it's not on the idle circuit.

I'll bet it will want 22-24 initial and 12-14 mechanical to hit your number. Go out and turn the distributor CCW when running, if it picks up rpm, it wants the timing. That should idle in the 850-900 range and not drop more than about 100 rpm in gear.

Unfortunately, lots of engine builders are terrible tuners for anything other than WOT. Street manners why you need that... :)
 
Cracked been,more than a few money rounds,on the street. (With N2O).Listen.
 
I'd suggest not to get the itch to hit the button, until you have the motor only tune up squared away.
 
Oh I'm not even close to hitting the button yet ripping on her. Just trying to get tinned. Haha sorry about the stock distributer, just had not gotten around to getting one and being in Canada getting HP parts ( for mopars) is a lil harder then you boys down south.

Thanks a lot cracked!! I'm still learning about ignition timing when it comes to more the. Just hitting it with a timing light and putting her to 2500rpm. ( inside the distributer stuff).
 
Wow lots of great info guys!!! It feels good to get some great input.
I already bought the converter ,but hey I'm not to upset.
Ill go to speed shop tommorow and grab a msd pro billet. Just called my buddie who works there and he said he had one in stock.

Ps if any of you boys remeber " Jimmy-boy" on here, I'm his son. I'm sure he got to know a lot of you when he was wrenching on his 69 valiant signet
 
Before you do anything, put the light on it and turn the distributor so you have 20-24* at idle. You'll likely have to close up the throttle plates as you add more timing because the idle speed will pick up. As you turn the idle speed back down verify that it still has the 20-24 timing you set it to start with. If it drops out, add it back in. At some point the mix screws should start to have an effect and engine will shut off when screwed all the way in..

On the MSD, put the 18* black bushing on it and one of the light silver and light blue springs. Toss the garage door springs it comes with in the bag... :)

If you want a limiter bushing that allows for more initial timing, I have them in both 10 and 14 degree versions.

The stock electronic distributors can work. They just aren't set up for anything with a decent sized cam.

I've fixed tons of cars that run just like your right now. Takes time to get your ignition timing set up well but it will tear it up once correct.
 
crackedback said:
Stock distributor? Really?

If you didn't have at least 18* on it, you aren't even close. That thing won't idle worth a darn with the total timing method and a stock distributor. The big rpm drop is the first clue, idle mix screws not killing it is second... it's not on the idle circuit.

I'll bet it will want 22-24 initial and 12-14 mechanical to hit your number. Go out and turn the distributor CCW when running, if it picks up rpm, it wants the timing. That should idle in the 850-900 range and not drop more than about 100 rpm in gear.

Unfortunately, lots of engine builders are terrible tuners for anything other than WOT. Street manners why you need that... :)
Click to expand...


It does pick up RPM!!
Thanks cracked, thanks alot. Ill get a new dist. And figure all this out
 
I'm gonna have to change the title of this thread to
( teach me how to dial my new engine in!!)
 
That doesn't matter here. Fix the carb ,and ignition curve first. 16-22 intitial,34-36@3000-3500 rpm total.
 
You get it right and you'll be amazed at how snappy it will run right off idle.

I bet it cranks over a bunch when starting and have to give it throttle to get it to fire.

Basics of tuning an engine... TIMING FIRST!!!
 
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