Author Topic: The pure stock quest for 11's continues  (Read 14765 times)

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Offline 4284spd

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Re: The pure stock quest for 11's continues
« Reply #30 on: September 18, 2016, 08:50:49 pm »
I had a lot of fun with my friends
Thats always the best part!
Bob Smith
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Offline Brian Conway

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Re: The pure stock quest for 11's continues
« Reply #31 on: September 18, 2016, 09:00:31 pm »
Thanks for the update.  I know your disappointed in the the times but on the up side nothing broke.  Brian
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Offline geraldt52

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Re: The pure stock quest for 11's continues
« Reply #32 on: September 18, 2016, 09:39:46 pm »
...I found out that chassis dyno numbers don't really mean as much as I thought they would...

Maybe not.  Dynos seldom lie, but sometimes they don't tell the whole story.  It sounds like you were using the initial timing to reduce the total timing and got better max hp numbers on the dyno, and then you raised the initial at the track and got better et numbers.  At least superficially that sounds like what it wants is more initial (for low end, as verified at the track) and less total (for top end, as verified on the dyno).  Of course the dyno probably doesn't register output until like 3K+, so you can't see what's happening down low on the dyno...and with an automatic on street tires down low matters.  If that's what it's wanting, then you'd need to take several degrees out of the mechanical advance to hopefully maximize both low end and top end output.  You can do that to try it out, at least temporarily, by putting shrink tubing on the stops in the mechanical advance.  Anyway, might be worth a try... 


Offline 428 CJ hardtops

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Re: The pure stock quest for 11's continues
« Reply #33 on: September 18, 2016, 09:41:53 pm »
At least I dropped the Ford Pure Stock et and mph record to 12.31 and 112.72 and now my 68 12 and 69 CJ Mustangs are the two fastest Fords .
had many 428 CJ and SCJ cars over the last 30 years.I currently own a 68 1/2 coupe and a 69 R code SCJ Coupe and a 70 R code SCJ Cougar Eliminator .I am looking for a 70 428 coupe if anybody knows of one for sale.

Offline Aussiebloke

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Re: The pure stock quest for 11's continues
« Reply #34 on: September 19, 2016, 04:04:56 am »
At least I dropped the Ford Pure Stock et and mph record to 12.31 and 112.72 and now my 68 12 and 69 CJ Mustangs are the two fastest Fords .
got to be happy with that!! :) :)
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Offline 428 CJ hardtops

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Re: The pure stock quest for 11's continues
« Reply #35 on: September 20, 2016, 12:51:37 pm »
I am happy with that but wanted to run faster .I talked to a buddy that noticed the dyno pulls were in a far lower temp than the track temp. That was part of it and the dyno guy said it might want a couple degrees more timing at the track. I will put it back in 12.01 trim and if the air is really good bump it down a couple degrees and go up two jet sizes in the rear and try it .I should have pulled 2 jet sizes out on Saturday the air was bad (over 3400 ft)but didn't realize it till it was to late .
had many 428 CJ and SCJ cars over the last 30 years.I currently own a 68 1/2 coupe and a 69 R code SCJ Coupe and a 70 R code SCJ Cougar Eliminator .I am looking for a 70 428 coupe if anybody knows of one for sale.

Offline 69cobrajetrugae2

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Re: The pure stock quest for 11's continues
« Reply #36 on: September 20, 2016, 04:23:00 pm »
It seems to me that you have to find 30 to 40 horsepower to reach your goal.  Will running a cold engine and therefore a cold intake manifold pack more air mass in the engine?  A magnetic oil heater to get 60 weight up to 250F and 30 seconds warm up should protect the engine parts and stop some of the heat soak in the combustion chambers.  The good part about the cast iron intake is that it takes a while to heat up.

A videotaped oscilloscope on the floorboard attached to the engine during a practice run will show if there is any appreciable rich or lean conditions in any of the 8 cylinders. To establish a baseline the equipment can be run on a fuel injected car under the same track conditions. 

Everybody talks about initial and total timing.  What about the timing advance through each 100 RPM increase in engine speed.  If 20 degrees of mechanical advance crank starts at 1300 RPM and ends at 2500 RPM with a 18 initial, is the spark advancing .6 degrees crank for each 100 RPM increase, or is it .3, 1.2 or .9 and scattering about?  The distributor would need to spin up at the same RATE OF SPEED on the distributor machine as it would on the track to get that answer. I don't know what RPM you guys launch at, but if it's 1800, is it possible to set the mechanical advance to come in at 2 degrees per hundred RPM from 2000 to 2500 RPM until the combustion turbulence takes over the advance at 2600 RPM? Or, since the torque load on the engine is high in the first 200 feet, would a trickle of advance past 2500 provide maximum cylinder pressure?  Finding the optimum timing recipe for every track condition would be necessary. Having a few differently curved distributors in hand on track day would be the way to go as I see it.

Again, I am not a seasoned racer but just a guy throwing some ideas around. 

When you do it, be sure to post a video!
« Last Edit: September 21, 2016, 10:17:03 am by 69cobrajetrugae2 »

Offline 428 CJ hardtops

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Re: The pure stock quest for 11's continues
« Reply #37 on: September 21, 2016, 02:30:45 pm »
It seems to me that you have to find 30 to 40 horsepower to reach your goal.  Will running a cold engine and therefore a cold intake manifold pack more air mass in the engine?  A magnetic oil heater to get 60 weight up to 250F and 30 seconds warm up should protect the engine parts and stop some of the heat soak in the combustion chambers.  The good part about the cast iron intake is that it takes a while to heat up.
The engine needs to be at 150 degrees or it feels flat ,Don't know how to get around that .It ran 12.01 last fall in 40 something degree temps with a 1.80 60 ft and 12.05 in 85 degrees with a 1.85 60 ft. It has the power just needs the 60 to do it .
A videotaped oscilloscope on the floorboard attached to the engine during a practice run will show if there is any appreciable rich or lean conditions in any of the 8 cylinders. To establish a baseline the equipment can be run on a fuel injected car under the same track conditions. 
On the chassis dyno the  AF mixture was very steady and flat.In much better air I will bump 2 sizes in the secondary jets ,in very warm might drop two
Everybody talks about initial and total timing.  What about the timing advance through each 100 RPM increase in engine speed.  If 20 degrees of mechanical advance crank starts at 1300 RPM and ends at 2500 RPM with a 18 initial, is the spark advancing .6 degrees crank for each 100 RPM increase, or is it .3, 1.2 or .9 and scattering about?  The distributor would need to spin up at the same RATE OF SPEED on the distributor machine as it would on the track to get that answer. I don't know what RPM you guys launch at, but if it's 1800, is it possible to set the mechanical advance to come in at 2 degrees per hundred RPM from 2000 to 2500 RPM until the combustion turbulence takes over the advance at 2600 RPM? Or, since the torque load on the engine is high in the first 200 feet, would a trickle of advance past 2500 provide maximum cylinder pressure?  Finding the optimum timing recipe for every track condition would be necessary. Having a few differently curved distributors in hand on track day would be the way to go as I see it.

Again, I am not a seasoned racer but just a guy throwing some ideas around. 

When you do it, be sure to post a video!
I will try some different thing with the dist springs .Right now the arms are slightly bent and the springs are loose at all times .Being we cant use all the full advance and over powering the tires is a constant concern slowing the full advance may give us the less is more sweet spot .A  buddy does a lot of dists or other racers and his 60 fts are consistent and very good (between 1.72 and 1.79 all weekend at the race, its a small bock but even his 440-6 pack challenger did better than nearly everyone with a little worse 60 fts than his small block car) He brings in full power at around 3700 rpm .I will keep my current dist the way it is and send him another to tweak . If I could get consistent mid to high 1.70's 60 ft times every pass could be in the 11's .
had many 428 CJ and SCJ cars over the last 30 years.I currently own a 68 1/2 coupe and a 69 R code SCJ Coupe and a 70 R code SCJ Cougar Eliminator .I am looking for a 70 428 coupe if anybody knows of one for sale.

Offline 69cobrajetrugae2

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Re: The pure stock quest for 11's continues
« Reply #38 on: September 21, 2016, 10:15:44 pm »
Okay thanks, I understand a little more about what's happening.

You are running a dynamic test program and your goal is to get a 1.70/60.  The track times you provided in your last post suggests that tuning the engine for more power won't help.   A 170/60 will pin you in the seat and half the weight of the front end will shift rearward on the launch.

If one is looking at the driveline and tires on a lift and visualizing a launch is happening, what improvement can be done to move the car forward faster and still keep the car stock.

The 2 patches of rubber in contact with the pavement are between 1 to 2 square feet. The rubber and asphalt are tasked to rapidly lift about a 1000 pounds and move another 2500 lbs rapidly forward.

At launch there is a windup and twisting of the driveline, then it unwinds, then winds up again. The windup and release is instability which is loss of traction control.  As the driveline winds up the leaf springs and axle housing twist and the tires are gripping the pavement and the work to lift the front end and move forward is going well.  When the twist hits the stops it unwinds and the stored energy has to go somewhere, it heads to the tires which causes them to break loose.

I don't know exactly what stock means with respect to what modifications are allowed.  I don't think it's against the rules to use stock parts that are worn out.  Ever drive a beat worn out hot rod and the darn thing hooks up for some reason?  If a car gets hit hard in an accident to the extent that the rear of the car is sagging to the left, will launch traction improve or be worse?  What if it's hit hard on the other side so that it's sagging to the right.  Suppose the toe angle of the rear tires is "off" so one rear is 5 degrees in and the other is 2 degrees out.

It might take a few well placed worn out parts, some loose bolts, and perhaps a twist or two to get her to pin you to the seat.


Offline 428 CJ hardtops

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Re: The pure stock quest for 11's continues
« Reply #39 on: September 21, 2016, 11:18:38 pm »
I had in my blue 69 CJ Mustang coupe a 1.57 followed by a 1.74 60 ft times .The track was good but the engine had the cam wearing out and with less power made it leave much harder without the ability to blow them off .I need to get a bit less initial power with full on shortly after and 1.70's should be doable slowing the dist is worth a try .Still could try the retard the cam 2 degrees and kill some bottom end torque to launch easier .
Tried 4 degrees in the 69 car and it was to much but you could nearly flatfoot it off the line and it ran good mph but gave up to much in the 60 ft  to give good et's.
had many 428 CJ and SCJ cars over the last 30 years.I currently own a 68 1/2 coupe and a 69 R code SCJ Coupe and a 70 R code SCJ Cougar Eliminator .I am looking for a 70 428 coupe if anybody knows of one for sale.

Offline Aussiebloke

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Re: The pure stock quest for 11's continues
« Reply #40 on: September 22, 2016, 06:01:41 am »
I for one am loving this crap!!! I know nothing about any of it or anything to be of any help. But love reading the thoughts on how to reach a goal. Do you change tire pressure much? and does it have an effect? I race motorcycles in Enduros, have done for years. I know how much it can effect a motorbike as can tires. I always preferred a one hr old tire that had the knobs rounded ,to a new one with  square edges. Much more predictable and neglegable difference in traction. Also a higher pressure, say 24psi was often better than say 13/14psi for traction. Hard to believe I know! (not in all applications though)
Carry on!!
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Offline 69cobrajetrugae2

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Re: The pure stock quest for 11's continues
« Reply #41 on: September 22, 2016, 10:26:48 am »
The distance the throttle pedal moves from idle to WOT in relation to the distance the carburetor butterflies move from idle to WOT is the throttle pedal angle. Imagine if the throttle pedal movement from idle to WOT was 12 inches. To maintain the same ergonomics as a stock throttle pedal the driver would be putting his for through the floorboard in a cut out recess as he applies WOT. Using this setup the driver would have a vast improvement in controlling wheelspin.  However it is not stock of course.

Disabling the accelerator pump to the extent that the engine stumbles off the line would control wheelspin but would be unpredictable due to altitude and variable track conditions, but it still might be a good way to do it. 

The mechanical advance should apply the shaft counter rotation smoothly and accurately as a Swiss watch. There is no advantage whatsoever to timing scatter unless it is temporarily used to launch the car.  The vacuum advance could be used to partially disable the engine but like the accelerator pump, it could be unpredictable by itself.

Here's one way to delay power during launch that would be consistent.

We know that full in advance of 36 to 42 BTDC at 2500 RPM is the sweet spot, more or less.

The initial timing is set to 36 to 42. The vacuum retard is adjusted to pull off 20 or more degrees at 10 inches of vacuum or higher, at 9 inches it gives the advance back to the engine.

If the launch RPM is 1600, then at 1500 the advance mechanism is scattering the timing to the extent that the engine has lost considerable power. The weight arms and springs are redesigned so they fight for control at a pre determined RPM range.

At the moment of launch the driver applies WOT and the misfire is present until the RPM reaches 1700.  At 1700 the advance mechanism hits the stops which is 0 advance.  The engine now has full 36 to 42 degrees with no misfire. The vacuum retard signal hose has a restriction which provides a slow dump of advance back to the engine because during launch the vacuum went below 9 inches and by the time the engine reaches 2500 RPM the timing is all in.  The slow dump should relieve any detonation.

That's the general idea.

Offline 161854

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Re: The pure stock quest for 11's continues
« Reply #42 on: September 22, 2016, 10:41:17 am »
  This is an extremely tough form of racing. Remember he's racing on Polyglas tires. Even with the help of a drag radial instead of a real drag slick like I run , the car would be deep into the 11's. Power management off the starting line is THE key to fast ETs in this case. You have to think outside the "regular" box in a case like this. Recalibrating the secondary opening , retarding the cam , less ignition timing , even using a carb squirter that is too big can "soften" the power initially to reduce tire spin. It is possible to have a mild bog situation that produces the quickest ETs. Even removing or reducing the accelerator pump shot as suggested above is a great idea. Hiding an MSD digital 7 with programable launch control , or going ALL OUT and using a Davis Traction Control system ( both illegal in this form of racing) would be the ultimate. "Crowned" 45psi front tires, low rolling resistance front end alignment etc. are all common to the class.
     To put it into perspective , take your own car to the track and "try" to get it into the THIRTEENS on Polyglas tires , then imagine how to go two seconds quicker with the same combination.
« Last Edit: September 22, 2016, 10:49:57 am by 161854 »
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Offline 69cobrajetrugae2

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Re: The pure stock quest for 11's continues
« Reply #43 on: September 22, 2016, 11:46:51 am »
The first thing that crossed my mind when I saw the ET progression in the stock class is that this guy has forgotten more tricks than most of us know, but there is always the simplest trick that sneaks under the radar and goes unnoticed or not shared with others.

These tests are done on the car on the track with G forces and real pavement.

The oscilloscope connected to the ignition system with either laptop or videotaped data logging the firing line.

Using the smog ports and tiny curved OS sensors will provide A/F information.

Vacuum and venturi velocity flow data from ports drilled in the intake manifold.

Cheap horsepower opportunities would be the expected result from running these tests.  Experience is great but few of us have forty years left to get it, and the guys that have it ain't sharing it anytime soon.

Offline geraldt52

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Re: The pure stock quest for 11's continues
« Reply #44 on: September 22, 2016, 12:13:19 pm »
Back in the day the first car I ever saw go 12s in Pure Stock trim was a '69 440-6 Super Bee with the lift-off hood...and everyone was in awe.  Very low 13s was already considered remarkable.  Of course the Super Bee had the benefit of F60-15s as standard equipment.  It is very difficult launching with any consistency on F70-14s...which is why the automatics are king.  Bear in mind that back in the day things like 2-1/2" engineered x-pipe exhaust systems weren't legal, nobody was using a balanced and blueprinted engine in Pure Stock, and track starting lines were little more than poorly maintained, repurposed asphalt landing strips.  What 428 CJ Hardtops is doing with a CJ Mustang is still pretty incredible.

I do have to say that I never imagined trying to concoct a scheme to intentionally limit power, I guess figuring the best way to limit and control power, especially with an automatic, was with your right foot...although it's hard to be consistent.  It'll be interesting to see how it is accomplished and how it works out.

I'm skeptical that the advance "curve" is the answer, as you blow through that rpm range in low gear pretty quickly with 4.11s and F70-14s, and never see that range in the upper gears.  I do think that finding the sweet spot of "total" and "initial" will help.  The fact that the dyno showed gains when total advance was reduced indicates that the engine was flirting with detonation at 42*, which makes sense...so limiting total while maintaining initial seems like the way to go.  I'm not sure if a vacuum advance is being used, but I'd probably lose the vacuum advance because it just complicates things in a race situation...vacuum advance is for street cars.

It all sounds like a lot of fun...and I'm jealous!