Author Topic: The pure stock quest for 11's continues  (Read 14766 times)

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Offline 428 CJ hardtops

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Re: The pure stock quest for 11's continues
« Reply #15 on: August 31, 2016, 10:27:05 pm »
   I know what you mean. I was just remembering what some of the F.A.S.T racers did . Like that 9 second '71CJ Mustang, impressive!
I saw Lane at the races last weekend. He bought that car in Reno and I hauled it to him .He may get it back out for next year to spank some hemi ass again.
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 161854

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Re: The pure stock quest for 11's continues
« Reply #16 on: September 01, 2016, 10:16:16 am »
     I have tremendous appreciation for "stealth technology". You'll be in the 11's with ease in cooler weather.
68 1/2 CJ FB San Jose white/blue "C" stripe Foulger Ford
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Offline crossboss

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Re: The pure stock quest for 11's continues
« Reply #17 on: September 01, 2016, 01:35:02 pm »
     I have tremendous appreciation for "stealth technology". You'll be in the 11's with ease in cooler weather.

+1. I also agree with Randy. 'Sleepers' are way cool.
<My old C.J. heap  aka  S-B Racing!
Current lifelong project: 1969 Mustang Fastback/FOX chassis, Powered by a modern Can-Am 494 (Boss 429), Kaase headed, Autolite 1425 cfm 'B' Inline carb, 6 speed, 4 wheel discs, ala Trans-Am style--Whew!

Offline 428 CJ hardtops

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Re: The pure stock quest for 11's continues
« Reply #18 on: September 07, 2016, 07:30:59 pm »
I have chassis dyno time booked for next Thursday , last time when I  brought the 69 CJ car there we got an improvement of 27 HP and 25 lbs of torque .I thought it was dialed in close then too. Don't expect that much gain this time but you never know .Half that would make me happy .Then on to the Pure Stock race .
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 Vcode

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Re: The pure stock quest for 11's continues
« Reply #19 on: September 12, 2016, 09:02:13 pm »
Steve,

Congratulations - I saw in the Oct. issue of Mustang Monthly's article on 10 Fastest Mustangs (1964-73) your listed as #1! ;)
It was good to see the top three spots were 428 cars and a total of four 428 in the 10 listed.

Dale.

'69 Mach 1 SCJ

Offline 428 CJ hardtops

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Re: The pure stock quest for 11's continues
« Reply #20 on: September 12, 2016, 09:08:56 pm »
I should be one and two by Friday morning ,weather permitting  . ;D
« Last Edit: September 12, 2016, 09:17:36 pm by 428 CJ hardtops »
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 Chris Teeling

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Re: The pure stock quest for 11's continues
« Reply #21 on: September 12, 2016, 09:28:50 pm »
Good luck!

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Offline 428 CJ hardtops

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Re: The pure stock quest for 11's continues
« Reply #22 on: September 15, 2016, 01:51:35 pm »
Picked up almost 11 hp and 20 lbs of torque on the chassis dyno this morning .Just playing with the timing .The jetting was on the mark with 64's and 72's .We will see how it runs tomorrow .
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 johnkn

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Re: The pure stock quest for 11's continues
« Reply #23 on: September 15, 2016, 09:43:43 pm »
Good deal.  Barry found my all iron motor did best at 37* on the dyno through the stock exhaust manifolds.  Take care..

Offline 69cobrajetrugae2

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Re: The pure stock quest for 11's continues
« Reply #24 on: September 16, 2016, 05:06:13 am »
I may or may not have accidently discovered a performance secret.

Some days my car seems to perform better than other days.  I've been puzzled about it for a while.

Is it a placebo effect?

Is a spark plug coming in and out?  FE's are known to develop an intermittent spark related misfire and go unnoticed.

I use metal tape to seal my fuel tank when not in use.  I fired her up one day to go for a quick spin, late morning mid seventies temperature, a nice sunny spring day.  When I shifted into second and tapped the throttle the tires broke loose.  There must have been a slick spot on the street, I thought.  A mile or so later it did it again. Then I gave it more throttle in second and it started going sideways. The next idea was that the clutches in my rear end just went south and only one tire was spinning. I checked it again and she was grabbing the pavement as usual.

As I was headed back to the house I pulled up next to a black rice rocket of some type at a stop light.  We we're at the limit line and traffic was very light. The light turned green and we accelerated through the intersection as one normally would.  As soon as I shifted into second HE decided to go for it and leaped ahead by 3 or 4.  My windows we're down and all I could hear was that annoying whine of the rice rocket pipes, so I nailed her real good.  I flew by him and he was a black spot in my rear view mirror.  I turned into my neighborhood and as he drove by his hand was in the air, thumbs up, nice sport he was.

When I arrived at the house it seems that the tape was still attached to the filler neck and was budging out.  I pulled the tape off and it shot fumes in my face under pressure.  I had about 3/4 tank of fuel.  At this point I started thinking, which is not always a good thing for me to do as some of you know.

As John schooled me in a previous thread, if the fuel aerates as it enters the bowl or if the fuel is low the main jets will not deliver as promised,  the result of which may not be noticeable.  Recently I ran a 4100 with the lid off and noticed the turbulence that the incoming fuel created in the bowl, notwithstanding the added turbulence of road and engine vibration.  It is clear to me that under WOT, if the fuel is entering the bowl as a frothy swill, the expected result will be a variable inconsistency in the fuel air delivery to the engine.

Our Holley's we're designed in 1967 or 1968 to run on straight run gasoline, and pass emission standards, and be serviceable for all temperatures and all altitudes.  There is, in my opinion, opportunities for horsepower and performance gains relating to fuel delivery modifications.  However, as John also pointed out, it's already been engineered for performance and safety and there are risks associated with modifying fuel systems.

The goal would be to have the float bowls full of non aerated fuel at all times.  The approx. 14 IWC of pressure in my tank that day might have allowed the pump to move a solid line of fuel to the bowls, the pressure and flow of which was a fit for the piping. The fuel pressure might have went up or down, perhaps by a 1/2 PSIG either way, which might have made a huge difference in float bowl fuel delivery and  aeration.

My first step to proving this theory is to have the fuel system checked and the results logged.  Next I would use a hand pump and gauges or manometer and introduce small amounts of pressure to the tank.  Next I would do 60 to 100 MPH romps on the same stretch of track, same day, with the speedometer under video recording. The first run is the car untouched. Add the fuel that was burned. Add 7 IWC and run again, and add the fuel that was burned. Repeat until the fuel pressure at the carburetor gets close to 6 PSIG.  View the video with a stop watch and record the 60 to 100 times and look for a run with the best time.

I did a performance verification in this manner.  What's weird is that all the runs will look identical from a time standpoint from viewing the videos.  But when I used a stopwatch there was .9 second difference on one of the runs!  I played the fastest and the slowest side by side and I did not notice that much of a time difference.

I hope this might help in the quest for the magical 11's.

Additional thoughts:

 If a long sweep 3/8 rubber hose is used from the fuel tank to the pump and from the pump to the carburetor inlet, then the volume will increase but it is unclear to me at this time what effect this modification will have on pressure.  If the volume increases then the pressure might drop unless the pump spring can compensate.  In addition, what effect will the increased volume have on the needle and seat as it closes off the fuel supply when the car is shut down after a run.  Simple tests after the modification will provide the answers. A 735 Carburetor must be bench tested near the existing carburetor as the engine is revved up to observe the float bowl operation under max fuel delivery both with the needle and seat open and then shut.

Author unknown.
Carburetors love fuel volume, but hate pressure. Pressure creates inconsistent aeration of the fuel in the float bowl, which causes inconsistent metering. Picture in your mind a water nozzle spraying into a bucket; the more pressure used, the more froth and air bubbles are created. If you have proper volume, the optimal fuel pressure is 4PSI for modern 2 and 4 BBL carbs. High horsepower drag cars may not be able to run this low because G force works against fuel attempting to travel from the fuel cell in rear to carburetors up front.
So now we have established that volume is critical. Let's examine factors that effect low volume, and there are many.

1st the obvious:
 Fuel Pump capacity
 Fuel Line size
 Fuel Pump style
 Fuel Pump placement

Capacity: Bigger is better. But… rating methods vary; some are rated with no output pressure or restriction. Others are measured at specified output pressure (A.K.A. 110GPH at 7PSI) (These ratings DO NOT specify the size, length, etc. of inlet of outlet size used.)

Line Size: Because manufacturer ratings fail to specify inlet or outlet size, we must assume the maximum size possible was used. Therefore, any reduction in size, no matter where it occurs, will reduce volume.

Beyond size, angles in fuel lines cause restrictions that reduce volume. Every 90° bend in the system reduces volume by 12%.

Example: Initial = 100GPH
 1st 90° = 88GPH
 Initial = 88GPH
 2nd 90° = 77.44 GPH

Look at the fuel systems on most all vehicles, race, street, off road, etc. Almost without fail you will find at least 1 90° bend, plus 45°, 30° etc. More common you will find 180°, 135°, 90°, 45°, one after the other.

So your 100GPH, by the time it gets to the carburetor, could be as low as 20-30 GPH. This is why fuel pump manufacturers rate GPH vs HP at what seems a completely excessive ratio. They realize that they must consider a worst case scenario: to safeguard against the most unacceptable installation.

 


Here is a great read.  http://www.musclecardiy.com/performance/holley-carburetor-fuel-and-fuel-supply-systems-guide/
« Last Edit: September 17, 2016, 05:08:10 am by 69cobrajetrugae2 »

Offline Aussiebloke

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Re: The pure stock quest for 11's continues
« Reply #25 on: September 17, 2016, 08:11:28 am »
Interesting. A mate has a mini tractor for tractor pulling. He destroyed 2 expensive engines before he found that the fuel line, about 1/2" was collapsing under FWO and starving the engine. Wonder if the rubber fuel hose could shrink? under hard fuel pump loads, and starve for fuel. Would only have to be a small amount. Dunno, just throwing it out there
1969 Candy apple Red R code

Offline 69cobrajetrugae2

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Re: The pure stock quest for 11's continues
« Reply #26 on: September 17, 2016, 01:36:36 pm »
I certainly missed the boat on this one, as your friend did Aussiebloke.

A wide band A/F sensor won't report on one or two lean, or rich cylinders, unless each exhaust port had it's own sensor.

I now believe that steady fuel delivery under G forces using a stock setup is a tough nut to crack.  There's no clear evidence that there is a problem and the car will seem to run good.  The dyno is a useless tool to identify or solve this issue, as outlined in the article.

In my view, the inlet to the carburetor and associated piping to and from the fuel pump needs to be upsized or at the minimum smoothed and massaged to provide the volume necessary for a smooth flow of fuel.  In addition, a cap or lid or fine mesh baffle inside the float bowl might help to keep the fuel from walling up and sloshing about which creates fuel aeration.

Addition.  Aussiebloke. With regard to your question of fuel line shrinkage and the associated effect on fuel delivery to the pump.  My car has metal lines with 3 short sections of rubber hose. One at the tank and one under the drivers seat area and another in the engine compartment.

If the hose shrunk then fuel delivery may stay the same, or increase or decrease. If the hose shrunk as we believe it would, then under vacuum, the flow of fuel may speed up through the restriction then decrease after the restriction which could create velocity. Kinks and dents in the metal line may actually improve flow.  Or the shrinking collapsing hose may hinder fuel delivery which would be our first guess.  I believe that fluid under vacuum behaves differently than fluid under pressure since it's pulled rather than pushed.
 
Vacuum theory and fluid dynamics and design require years of specialized training and test experience to get it right.

Your friend that lost the engines may be correct that the fuel line collapsing under vacuum caused the engines to fail.  However, if the rubber line was full of fuel and the vacuum side of the pump collapsed it then might have been a restriction somewhere in the line or the pump was oversized for the application.

There are formulas to estimate fuel flow to power output.  Check the pump output not from a open hose but through the needle and seats of an identical carburetor. With real world restrictions the pressure rises and the flow drops.  Because the pipes are a fixed orifice the only way to get more flow is more pressure which is more fuel turbulence and aeration.

 My guess is that our cars are always on the brink of fuel starvation but we never knew it.
« Last Edit: September 17, 2016, 06:11:51 pm by 69cobrajetrugae2 »

Offline Aussiebloke

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Re: The pure stock quest for 11's continues
« Reply #27 on: September 18, 2016, 06:21:37 am »
I know as far as an air hose, as an intake track on a modern engine, goes, if it get soft from heat, and does not have a spring in it to stop it from collapsing, it will most certainly affect flow!! Had a 4wd that as soon as you got up to a certain speed would just die!110kph. as soon as speed decreased to around 40kph it would start running again. Took 4 days to track that down!! I'm thinking fuel would be no different. Dunno. That was purely a heat related issue as to it collapsing, but it was the amount of air being sucked that caused it to collapse due to vacume it was creating
1969 Candy apple Red R code

Offline Brian Conway

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Re: The pure stock quest for 11's continues
« Reply #28 on: September 18, 2016, 11:40:38 am »
author=428 CJ hardtops
Picked up almost 11 hp and 20 lbs of torque on the chassis dyno this morning .Just playing with the timing .The jetting was on the mark with 64's and 72's .We will see how it runs tomorrow .

So... Race results ?  The good the bad ?  Brian
65 5R09A 4 spd  GT  Built 5/29/65 
69 9T02R 4 spd  SCJ Built 9/19/68
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Offline 428 CJ hardtops

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Re: The pure stock quest for 11's continues
« Reply #29 on: September 18, 2016, 07:16:08 pm »
author=428 CJ hardtops
Picked up almost 11 hp and 20 lbs of torque on the chassis dyno this morning .Just playing with the timing .The jetting was on the mark with 64's and 72's .We will see how it runs tomorrow .

So... Race results ?  The good the bad ?  Brian

I found out that chassis dyno numbers don't really mean as much as I thought they would. He checked the timing when I got there at it was 42 by his timing light it was 40 by ours .The carb was spot on from the get go AF numbers were on the money and steady .
He took 2 degrees out and it made more power ,then another and another till it maxed out in gains .  Got to the track and first pass was 12.77 then a 13.14 and a 13.34 the mph was off also but the track was a bit slick as usual and the air wasn't ideal
.Decided to put 39 degrees timing back in it and went a 12.31 at 112.72 ,it ended up being the best pass of the weekend with the 60 ft times off a bunch and the air factoring at over 3000 ft .I was disappointed some in the performance of the car but Tom Shaw shot the car for a future magazine article and I had a lot of fun with my friends . Met some forum members there and had fun talking cars with them and many others .
I know on a better track with better air it has the 11 in it even if the driver doesn't . :D
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.