Getting Dad his <12.99

[TheLetterJ]

First post in the racer's forum. Sorry, I'm kinda long winded... some backstory first:

Thanks guys. It really has been an emotional roller coaster getting to this point. My dad bought the car for my mom as her first car in 1975, he already had a '72 Demon 340 at that point (which later got totaled, while parked, by a drunk driver in front of his parents house.) Myself and my 2 older siblings all came home from the hospital in this car after we were born. At some point the '70 Road Runner 440/4spd came along and the Demon moved to a storage yard. The daily driver became a K-car ("a door is ajar" if anybody remembers the alert system that spoke to you for everything?!) and the guzzler/rusty Road Runner was sold (I still remember the day it drove away for $1000!!!)

The Demon sat for too long and rotted out (as they all do) and after my mom passed (at 37) my dad decided it was time to start picking away at it... instead of jumping straight in, he and my brother restored my brother's '71 Swinger for "practice" using the Demon for reference. Once that was complete, we started in on the Demon using the Swinger for reference.

It was always a "when I feel like it, I'm in no rush" kind of project which took right at 20 years (with a few fires lit under his butt along the way, his neighbor and myself jumped in anytime he'd let us) to get back on the road. I think one of the biggest motivators to finish the Demon was when my brother passed at just 35 in 2017. I can't count how many times I heard my dad say "I gotta get it ready for Spring Fling" Unfortunately his health started deteriorating over the last few years so he only put 111 miles on it before he passed just over a year ago at 64... but damnit, he finished it! Most of his friends and family never knew he got the car done until they saw me drive it to his funeral.

It's not perfect, but he was trying to keep things accurate, he even took pencil rubbings of some of the decals so they could go back on just as crooked as they were from the factory. The 6 pack had been pulled from a T/A Challenger at his high school job (a Chevron service station, back when they'd do real service like engine rebuilding!) in favor of a 4bbl, so he got a good deal on the takeoff parts. His parents (my grandparents) wouldn't let him buy the T/A he wanted because it was (according to my grandparents) a "race car."... but he had a plan to build his own 340 6 pack, so originality be damned, the 6 pack stays on this car! I'm still picking away at the details, but my dad will be proud to see his baby finally make it to the show... even though he'd have given me a hard time that "this ain't no trailer queen!"

I look forward to hearing others' stories at the show!

The last conversation I had with my dad before he passed, he asked me to get him a "...12 second time slip, gotta be a 12.98 or better (because a 12.99 could be a flickering 13.00!)... no nitrous!" in his '71 Demon. I took it to the car show he'd been working towards getting ready for while it was still stock appearing and I've been picking away at getting it track ready ever since.

My goal has been to set the car up the way I think he'd want it and use the engine as he built it, so I've been trying to get the converter/gears/tires/suspension to work the best that I can around it. He wanted it to go down the track at least *looking* like it would have if it were a daily driver/family car.

Some basics:
1971 Demon
340 with ~1,000miles on it
.030" overbore w/JE forged pistons 10.5:1 c.r.
MP 292/.508 cam
OEM iron heads w/2.02 intake valves, "gasket matched" and minor bowl work
6 pack from a TA Challenger
TTI stepped headers w/3" collectors and 18" collector extensions
MP electronic ignition, 35° total advance
TF727 w/B&M shift kit (will be manually shifted at ~5800-6000rpm)
Dynamic 9.5" ~4,000 stall torque converter
8 3/4 rear with 4.56 gears and a Suregrip with all thick clutches

275/60/15 Mickey Thompson ET Street R on 15x8 rally wheels
Dr. Diff inboarded spring hangers
Calvert split mono leafs mounted in the upper hole along with 3/4" lowering block
Caltracs bars mounted in the upper hole with 1/6 turn preload
Viking double adjustable shocks front & rear
Slant 6 torsion bars
front swaybar removed

I have not weighed the car but if the factory weight of ~3200lbs was accurate, it should still be right about there. I'm ~190lbs

I've never run on a drag strip. I'd like to get as dialed in as I can before taking it to Famoso as I'd *really* like to hit his time on the first outing... ideally the first pass. I'm still playing with rear shock settings, tire pressure, and what rpm it leaves from the best. I'm still having trouble getting it to hook, while I have access to flat farm roads with good asphalt... they're dusty. Does it sound like my combination should hit the desired 12.98 (or better) assuming I don't screw it all up as a driver? The time and expense of taking it to the track doesn't come easy for us, does it sound like I've reached a point that I just need to take it and see what it'll do? Any glaring issues you feel I need to address first?

 

[TheLetterJ]

More rambling...

I don't put much faith in it, but the Wallace calculator says 3400lbs will go 12.98 at 105mph with only 307hp. I'm assuming that's based on EVERYTHING being dialed in perfectly with little/no power loss or slippage and perfect driving? I'd certainly like to think I'm making more than 307hp There's a Mopar Muscle (?) magazine article from ~25 years ago with a virtually identical engine build that made 392hp (which, according to Wallace, would run a seemingly optimistic 11.97 @ 114) that my dad used to help get the 6 pack setup but this engine will never see a dyno to know where it falls, and I can't count on perfect driving being my first time out.

I've looked over the "post your 12 second small block combos" thread and it *looks* like I should be in the zone without cutting it too close?

 

[318willrun]

Goodness, looks like an 11 second combo to me.

 

[mopowers]

If that combo doesn't run 12's something is wrong.

 

[crackedback]

All about the 60' with ET.

JMO, put the bars in the lower hole on your caltracs, barely touching spring

Has plenty to run 12.9x or better.

Looks like a car a friend owned in Costa Mesa.

 

[Demonx2]

IF you can get it to hook, 12's will be no problem. And I wouldn't sweat it too much as street traction is WAY less than a properly prepared track. You have a pretty well matched and coordinated setup. Just be sure the 6 pack truly opens all carbs up before you go to the track. Maybe start at about 20 psi in those tires. The car could also run close to the same thing with a 4.10 axle which would make traction less of an issue. But I'd give what you have a chance at the track and smile wide when you click off a 12.70 pass!

BTW...that's a real beauty you have there! (Ok, ok...I may be a little biased towards Demons....!!)

 

[67Dart273]

With those gears if that won't get into the 12's there is seriously something amiss

 

[GTX JOHN]

We will be @ Famoso in entire of the last week in
Sept. and would be delighted and honored to tune
and work with you on your Father's Duster.

My boys and I have raced A body Mopars for a very long time.

Google: John Irving Racer
and my son Jon Irving Racer

 

[autoxcuda]

Love this car and story with it.

So cool when you brought it to share at Spring Fling.

 

[Locomotion]

Does the Mopar Muscle article that was used as a reference for the engine build include any tuning info for the Six Pak set-up? A 6 bbl combo tends to be more difficult to tune than a single 4 bbl. There have been instances of experienced racers switching to a 4 bbl and going faster! That may have been the case when he originally got it off of the Challenger T/A.

I agree that it's a great combo but 4.56 may be a bit much for a 28.2" tall tire.
You can bump up the front tire pressure a bit for less rolling resistance while at the track.

 

[TT5.9mag]

Personally, if traction is an issue I’d ditch the 3/4 blocks before I did any tuning on shocks or mount locations. And if you need help tuning it, take @GTX JOHN offer to help. You will not find a more experienced racer offering to share knowledge.

 

[TheLetterJ]

All about the 60' with ET.

JMO, put the bars in the lower hole on your caltracs, barely touching spring

Has plenty to run 12.9x or better.

Looks like a car a friend owned in Costa Mesa.

Any adjustments I've tried have been in the name of getting out of the hole. I figure if it hooks well off the line, the rest of the pass is what it is when the pedal is buried in the floor. That said, I started with the Caltracs in the lower hole, just touching the spring, but it would just blow the tires off. I played with rear shock settings and it didn't seem to help, so I tried the upper hole which made some improvement, then added a little preload, which made a little more improvement... but it still spins. I'm sure there's more improvement to be had with more rear shock adjustment. Front shocks are set full loose on rebound (which isn't as loose as I thought they'd be) and full stiff on compression.

I realise that a prepped track should help traction a significant amount, but since I'm not familiar with racing on a track, I don't know just how significant that is. That's why I've been focusing on trying to get a good 60' before I take it there. Do you think the traction is so much better on the track that a Caltracs/shock setup that hooks on the street will hit too hard at the track? I'd just been figuring that it wouldn't upset anything at these power levels?

On a similar note, the ONLY time I've got the car to dead hook, there were 3 extra bodies in it! Even with the extra weight in the car, it still left way harder than it ever had. I had been planning to ditch some weight from the really easy places (spare tire/jack/trunk liner/half tank of gas/no breakfast burrito/etc.) but that would all come off the drive tires. That got me thinking that maybe the benefits of weight loss (in those places) won't be worth the loss of ground pressure on the rear wheels?

 

[TT5.9mag]

Caltracs, mono leafs, drag radials, and adjustable shocks should hook on a dirt road with 300 hp. Ok I’m exaggerating but you get my point. Loosen the front end up a bunch, and see post 11.

 

[TheLetterJ]

Personally, if traction is an issue I’d ditch the 3/4 blocks before I did any tuning on shocks or mount locations. And if you need help tuning it, take @GTX JOHN offer to help. You will not find a more experienced racer offering to share knowledge.

Can you elaborate on that? I started without the block and didn't care for the rake of the car and the lack of caster that came with it. I wanted to shim the pinion down a bit so I threw in the block (it's actually a cut down overload spring from a truck, bolted into the pack) at the same time as I installed the shims for a total of 1" more drop. Pinion is now 1.5-2° down from parrallel with the transmission tailshaft. It is my understanding that lowering blocks with Caltracs have much the same affect as raising the front of the bar since they're effectively lowering the rear of the bar relative to the chassis/axle and it should add more hit/bite to the suspension. I can't see it contributing to axle wrap any meaningful amount in this configuration, what would the downside be?

 

[TheLetterJ]

We will be @ Famoso in entire of the last week in
Sept. and would be delighted and honored to tune
and work with you on your Father's Duster.

My boys and I have raced A body Mopars for a very long time.

Google: John Irving Racer
and my son Jon Irving Racer

That's very gracious of you and I might take you up on that offer!

 

[middleagecrisis]

"275/60/15 Mickey Thompson ET Street R" is the biggest challenge here. People get them to hook, but they've seriously dialed in their chassis. Put a set of ~ 28x10" slicks on it with about 12-15 psi, leave at 4000-4500 RPM and you probably crack into the high 11's. Run those ET Streets and you're going to have to run it more times than you want to get it into the 12's. Just my .02 worth.

 

[TheLetterJ]

Love this car and story with it.

So cool when you brought it to share at Spring Fling.

I'm glad we took it to Spring Fling first. If I can get a time slip with his number on it, we'll be at the following Spring Fling and we can enter in the race car class! (and look out of place)

 

[TT5.9mag]

Can you elaborate on that? I started without the block and didn't care for the rake of the car and the lack of caster that came with it. I wanted to shim the pinion down a bit so I threw in the block (it's actually a cut down overload spring from a truck, bolted into the pack) at the same time as I installed the shims for a total of 1" more drop. Pinion is now 1.5-2° down from parrallel with the transmission tailshaft. It is my understanding that lowering blocks with Caltracs have much the same affect as raising the front of the bar since they're effectively lowering the rear of the bar relative to the chassis/axle and it should add more hit/bite to the suspension. I can't see it contributing to axle wrap any meaningful amount in this configuration, what would the downside be?

Using blocks in the rear to get caster numbers in the front is the wrong way to do it. I feel the same way about pinion angle. Ride height is about all they are good for and that’s personal preference. While the block may have helped that situation, they add leverage to the spring and initiate wrap when load is applied. Basically fighting what the caltracs are designed to eliminate. You’ll have the best results when the spring pad on the axle tube is bolted directly to the spring. And get your alignment through other methods.

 

[TT5.9mag]

Because I was curious, and because my last few posts about caltracs and lowering blocks were mere speculation, I called Calvert and asked. The blocks absolutely do affect how the bars work and increase the leverage on the spring the way I thought. He did correct me by saying most guys are able to tune around it with shock settings and bar placement. He also warned me about the bars relationship to the ground with too much block. They only recommend using “up to 3 of the stackable blocks” they sell. Which are 1/2” for a total of 1-1/2” of drop.

 

[TheLetterJ]

I appreciate that you have enough interest in the matter to make a phone call about it!

I do understand how the block gives the axle more leverage against the spring, making the Caltracs work harder to control spring wrap, I just feel that the added 3/4" was not enough to cause problems in this scenario. That said, and I know it's a different world, but a very good friend of mine runs 4" lift blocks with Caltracs on a ~2000hp/3800lb sand dragster that runs 3.7's and spring wrap has never been an issue. He's actually the one who finally convinced me to run Caltracs mostly due to being able to preload each side differently to make the car go straight.

I did not lower the back to gain caster, but that was a welcome (albeit minimal) byproduct. I was trying to compensate for the ~1 1/2" that the rear tires raised the car. Between the small block, and using the upper hole in the front spring hanger (which is the reason I needed to shim the pinion down) I pretty much got it back to factory height. My dad had the front end sitting on the bumpstops too, but I raised it about 1/2 way back up to factory ride height from there. Now that I have ride height set where I want it, I will be realigning the front end. I'm planning to max out caster at the upper arms (as far as I can while keeping both sides the same), then shim the knuckle out at the lower balljoint (if necessary) to bring camber to zero, then set toe at 1/16".

Here's where it sits now:

 

[TheLetterJ]

Does the Mopar Muscle article that was used as a reference for the engine build include any tuning info for the Six Pak set-up? A 6 bbl combo tends to be more difficult to tune than a single 4 bbl. There have been instances of experienced racers switching to a 4 bbl and going faster! That may have been the case when he originally got it off of the Challenger T/A.

I agree that it's a great combo but 4.56 may be a bit much for a 28.2" tall tire.
You can bump up the front tire pressure a bit for less rolling resistance while at the track.

Yes, the article had tuning info for the 6 pack which he closely followed. I know that even "identical" builds don't necessarily make the same power, nor require the same tune, but it should at least be within the ballpark and it runs well enough that it's probably outside of my wheelhouse to dive deeper into jetting changes.

4.56 might not have been my first choice, but it's what I had and the numbers actually penciled out pretty nicely for what I expect to be a sub-110mph car with an engine that is happy up to ~6500rpm (calculates to 110mph @ 6000rpm with no drivetrain slippage.)

 

[autoxcuda]

I'm glad we took it to Spring Fling first. If I can get a time slip with his number on it, we'll be at the following Spring Fling and we can enter in the race car class! (and look out of place)

 

[furrystump]

Absent any influence that the bars will have. The lower blocks should decrease your % of rise. There by reducing the separation of the body and axle. Draw a line from the tire contact patch, through the instant center (absent Caltrack influence is the front leaf spring eye) out through the car. Where that line intersects compared to the center of gravity determines how easily the car will seperate. Assume your center of gravity is about where the radio is. The farther towards the rear of the car the intersection is. The easier the car separates. Lowering the rear of the car reduces the % of rise. Not a horrible thing, because A bodies have a bunch of % of rise. Never worked with Caltacs, but as I understand them they move your instant forward. Almost like a dynamic ladder bar. That also softens how the axle transmits force to the car. You have the combo to reach your goals pretty comfortably. I would definitely take GTX John up on the offer to help at the track. First time it can be pretty intimidating and someone to video the car would help a bunch. Please keep us updated!!! I would spend the $80 to buy a fire jacket……My way of saying you might be a second off your goal.

 

[furrystump]

Also, other than tuning the tire pressure by looking at the contact/rubber marks. Any settings you have on the street are going to be pretty far off on a prepped track. A prepped track will steal your shoes then your socks! For example It will hook much harder, topping out the front suspension much faster, upsetting the rear tire.

 

[BSB67]

I’m not sure why your goal isn’t 11.98.

It should run 12.70’s at 112 with 3.23s and P225-70-15 BFG tires.