PB 68 Charger

[cdr]

Well new slip on the right, I ran 11.11, picked up 2mph in the 1/8 & lost 2mph in the 1/4, when I hit high gear it just laid down, fuel problem ? trans ? will figure it out. Race weight 4050lbs drove 130 miles round trip. I am so mad at myself, I did not look at my AFR gauge when it happened. 4 hours one run

 

[cdr]

 

[HEMI-ITIS]

Sure sound like a fuel problem be it jet or pump.Was tat the 1st pass of the day? Did anything else change before that pass???

 

[cdr]

1st & only pass, the 1st slip is from a year ago. when I shifted it was pulling & the laid down like going lean

 

[BSB67]

Well new slip on the right, I ran 11.11, picked up 2mph in the 1/8 & lost 2mph in the 1/4, when I hit high gear it just laid down, fuel problem ? trans ? will figure it out. Race weight 4050lbs drove 130 miles round trip. I am so mad at myself, I did not look at my AFR gauge when it happened. 4 hours one runView attachment 753349

Love those DAs. My limited observation suggests the 1/8 mph + 23 is usually close. Your time slips are 25 and 21.

Fuel pressure/delivery would probably my first look.

Glad you got out.

 

[HEMI-ITIS]

I know the feeling well.Do you data log or read plugs?
Month ago I went for a test hit in the street.It was 55* that day,but by the time I got down to my rental garage and took the car out in was in the high 40's with crisp air! When I drove to my "spot" and rolled into the throttle,soon as I went WOT it went lean and fell on it's face.
Do you have any idea what the DA was like on your last pass then this one??

 

[cdr]

Yes it is written on the slip, last year 1750, lastnight 254, I have data log but I have to use my laptop, and it was at the house & by the time I got home 65 miles later the info I needed was gone

 

[HEMI-ITIS]

Well that sounds like at least 3 jets larger to me! Need to tune for the weather that can change from morning to afternoon! It leaned out and fell off.........

 

[PRHeads]

The 7.07 in the 1/8 works out to a 11.09....... so depending where you were on the track when it layed down....... you might have gotten most of it.

No problems encountered until high gear is usually a sign of a fuel delivery issue, not so much jetting of the tune up.
The fuel pump isn’t keeping up with demand, and the floats gradually drop until the float level is below the Jets, or at least low enough to keep it from properly metering fuel.

What does your fuel system consist of?

I can tell you this, when I had my car running 10’s, had to run with at least 2/3’s of a tank of gas, or it would uncover the pick up.

I figure you’re trying to not scare yourself, and are sneaking up on the 10’s.

I’d try and look at the schedule for the track you go to, and go on a test and tune day.
It’s pretty hard to sort through issues when you’re only getting 1 or 2 hits at the track.

 

[cdr]

The 7.07 in the 1/8 works out to a 11.09....... so depending where you were on the track when it layed down....... you might have gotten most of it.

No problems encountered until high gear is usually a sign of a fuel delivery issue, not so much jetting of the tune up.
The fuel pump isn’t keeping up with demand, and the floats gradually drop until the float level is below the Jets, or at least low enough to keep it from properly metering fuel.

What does your fuel system consist of?

I can tell you this, when I had my car running 10’s, had to run with at least 2/3’s of a tank of gas, or it would uncover the pick up.

I figure you’re trying to not scare yourself, and are sneaking up on the 10’s.

I’d try and look at the schedule for the track you go to, and go on a test and tube day.

Been trying to go test & tune for 4 months, since January, rain rain rain , about 2 months ago rented HRP [Baytown} drove 130 miles on drag radials in the rain to get called off . I have a 255lph EFI Walbro intank pump, return system set @ 6psi said to be good for approx 800 hp.
I was thinking my tank vent might not be large enough, it is about 1/8 inch vent hole.

 

[cdr]

I could feel it quit pulling, struggled to pull over 5k

 

[dvw]

How about headwind? Running into a 10-15 mph headwind, mine picked up a solid 2 mph in the 1/8 last time out. But the 1/4 was down 4 mph. This was consistent with others at the track the same day. Also D/A at 250ft it may have been lean. Not to say it couldn't be a delivery issue. But what changed from the last time out in the fuel system?
Doug

 

[PRHeads]

Have you flowed the system at 6psi?

I put a ball valve in the end of the hose, and adjust it so it maintains 6psi....... the time how long it takes to fill a one gallon can........ and see if that number works out for your fuel demand.

The only flow rating that matters is how much the system will pump while maintaining the system pressure you’re running.

I watched the run....... I’m not used to seeing cars run with street gears.
You’re way down there by the time you hit high gear.

Did you not attempt any more runs, and that’s why you only got one pass?

 

[cdr]

DVW, the wind had died down to about 4 mph.
Dwayne, there where a lot of cars there, sat in the staging lanes for hours, made a pass,went to my pit & was going to pull a spark plug & then I heard them say staging lanes are closed, I was not happy, it was a long drive for one run, I have not flowed the system yet but I will, also I rechecked the vent hole size & it is .140 diam, will do some checking.

 

[PRHeads]

I doubt it’s the vent....... but I’d still address it.

When my heap was running 10’s, it still had the factory 5/16” fuel line and pick up, a carter race mechanical pump, and $4 Wix in line filter between the pump and carb.
In good air it would go 126+.
No fresh air, crank driven water pump, battery up front, etc.

When I put the 383 in the car I used all the same stuff, since I figured the 383 made 75-80 less hp, it should be more than enough.
Best speed with the 383 with that set up was 119.
I ended up pulling out the stock tank and line, installed a cell in the trunk, Mallory 140 pump, 1/2 line to a BG 2 port regulator, #6 lines to the carb.
At the same time I also installed a 6bbl hood, and removed the rear seat, heater, and wipers.
First pass out with that set up went 123mph(4mph better) and the car def pulled much harder in high gear.
How much of that was the fuel system, how much the other stuff...... I have no idea....... but my gut feeling is a large part of it was the fuel system.
And, the previous 119 was done in much better air.
After the first pass the speed was in the 121.5-122.5 range, which I thought was odd since the first pass was almost never the best one of the day.
After getting the car back to the shop I discovered the right front wheel cylinder had seized in the “on” position and that wheel was very hard to turn.
Apparently it stuck when I jammed on the brakes that first run.

The first thing I thought of after that first pass was that I wished I’d had that stuff done to the car when it had the 448 in it(of course that likely would have just resulted in pulling an ly rod apart).

I almost forgot the reason for this post.......
When I was running the stock fuel system, it also had the stock vent.
Although at that performance level...... I wouldn’t try and run the stock system anymore........ or the stock vent.

 

[cdr]

I will do some checking & let Y'all know, the hard part is I dont want to go testing on the streets @ over 120 mph, the Police will say you were racing & take your car from you, my local track shut down for repairs, Lone star motorsports park, but I think they are full of SH_T.

 

[bobtile]

If jetting was the same from a 1750da to a 250da, I'll bet you were lean.

 

[bobtile]

You should check your fuel pressure regulator. Sometimes the loosen up.

 

[cdr]

You should check your fuel pressure regulator. Sometimes the loosen up.

Thank you Bobby

 

[cdr]

Thanks to Member PRHeads for steering me in the right direction, the lock nut on the regulator came loose & some other things added up to no fuel volume, pressure was 6 psi but no volume.