Made 4 passes today at t&t. Changes since last time include an air bag in right-rear (8lbs).
Run-1
1.473
4.324
6.735
102.29mph
8.835
10.624
125.02MPH

Run-2 (No changes)
1.469
4.323
6.738
102.07mph
8.841
10.632
124.87mph

Run-3 Changes-Jet up 2 sizes fr & rr, ran in left lane and did'nt line up in the groove very good.

1.519
4.37
6.786
101.9mph
8.889
10.682
125.02mph

Tried to switch carbs before the last run. I wan't to try an hp950 I have but ran into problems and had to put old carb back on.

Run-4 (Same as run-3, back in rt lane)

1.463
4.297
6.701
102.52
8.796
10.581
125.25mph

I'm real pleased with how the car is hooking-up and et'ing but the mph has me wondering if I don't have a fuel delivery problem. Here is a sample of a previous run.

1.503
4.373
6.806
101.16
8.916
10.708
125.56

Now I'm +1.36mph at the 1/8 but -.3mph at the 1/4. Seems like I would be closer to high 126 or so. Any thoughts?

Also, for those that followed my last track results thread, there was no head wind today and the car ran super straight, no drifting.

Thanks for looking.

Sweet Man !!

Congratulations,,,what year Chevelle? how much does she weigh? What were your previous bests? I know I must have read the thread,just got a memory like my :eek:

John,

Congrats on the new best! graemlins/beers.gif

I'm sure a little track time and a new best helps ease the frustration of your other "issue".

Glad to hear the car was going straight this time. It's amazing what a little wind can do to our big 'ole honkin cars. Imagine what it must be like in some of the 10.5 Outlaw cars and such.

Something is definitely up with the MPH on the back half of the track. Your passes today should have been in the 126.5 - 126.9 MPH range or so.

Did you notice anything funny up top? Do you have a fuel pressure gauge? What does your fuel system consist of?

great runs. looks like it was responding to the "MORE" changes. Did you drive it to the track?
graemlins/waving.gif

Those are great runs John graemlins/thumbsup.gif I went out to Sealy for a drag race fix and found the gates locked. We had a brief drizzle and it shut the track for the weekend graemlins/sad.gif .... I assume you ran in Baytown ?

What size fuel line do you have from front to back and what fuel pump are you using ?

Thanks fella's!

Robert- just a freckle over 3500 with a full tank and me. Previous best was the above 10.70. Actually I've got two 10.70 passes before today.

Paul- I only run 110 oct. I'm 85 miles from the track so I tow it. I've got a lot of respect for folks that can drive there 10sec n/a small block cars to the track. I've just had too many "issues" come up while at the track to be paying that $200 tow bill home. Plus that $5/gal gas gets expensive.

Jason & John- the fuel system consist of a -8 line from the cell to a "pre-filter" to a Comp140 then -8 to a Comp140 filter, -8 to Mallory reg, -6 to each fuel bowl, -8 return line. I don't have a gauge visible during run yet, just one mounted off the regulator. I ran at Baytown. There's also a new 1/8mi track opened up in N/E Houston that I'll be trying soon. It'll be a lot closer.

John, looks like the mph gain in the back half on your previous best was 24.4mph. The back half gain on your new best is 22.73mph.It's possible that it's struggling a little in the middle.
The e.t. reduction probably came from a combination of better traction and no wind. It's possible that now that it's hooked up the motor is seeing more fuel demand.
Try raising the floats a few flats and see if that helps. If it does, the motor wants more fuel supply and you may have to work on the carb's fuel curve and fuel supply volume. JMHO!

Real nice passes by the way!

Randy

Great #s.......One of my friends are trying to do just that and we will see come spring....Congrats...... graemlins/thumbsup.gif

John,

Forgot to mention. Good to see the 60 footers coming around to where they should be. How is the car leaving now? On the passes that it spins what does it do?

Just as a datapoint my old 383 SBC combo picked up right at 22.5 MPH on the back half of the track compared to your 22.73, 22.8, 23.1, and 22.73. The kicker is that I was running 10+ MPH slower in the 1/4.

What type of "prefilter" are you running? What size are the inlets of the Comp140 filter? What kind of fuel volume does the system free-flow?

Where were your shift points this last outing compared to previous runs?

Any brakes dragging? Timing settings possibly moved? Did valve lash open up some? Did you get to check any plugs after a pass?

At first glance, it looks like it liked more jet. I would try making 2 clean passes like it sits and then move up 2 more jets front and rear. Then make at least 2 more clean passes and compare.

What was the DA for this outing vs. the last?

Jason, on a spinning 60' it feel like just that, spin. It spins right from the get-go and the front does not rise as much. If I had been lined up in the groove I'm sure the 60' would have been much better on that pass.

The pre filter is one of these Summit jobs. It has the removeable metal mesh screen. It's not restrictive at all as far as particle size goes but maybe I need a set-up with a larger suction line? The comp filter has dual inlets and outlets but I only use 1 per side. It uses the 3/8npt to -8an fittings.

Haven't done any free flow testing. Shift points today where 6400 1-2 and 6600 2-3.

Front brakes are the Wildwood disc's which do have a little drag. Back breaks I haven't checked.

I just went through the lash before my last trip 2 weeks ago. Timing still at 35. No spark plug readings.

DA from 10.70 pass was 1700. Yesterday -200.

I just remembered that I also hollowed out my T-stat to allow lower staging temps (thanks Garret, ;) ) and also the headers have been coated since the 10.70 pass. Maybe thats helping with lower under-hood temps at the starting line and by the time I'm past the 1/8 the under-hood temps are the same as previously due to air evacuation.

Great runs! I hope my 60's come around to something like that next time I go out!


JIM

Good numbers John, really good numbers. Makes me wish I was still in the Houston area to watch guys like you and Wayne run your cars. graemlins/thumbsup.gif

John, you may want to go with a Carter 172 fuel pump..... :rolleyes:

Hey guy's it's been a while. If any of you guy's ever need a 1/8th mile track for some testing and tuning, let me know. We just opened a new facility near Angleton and sometimes we go out there for a little testing during the week. It's a little dusty at times but hopefull the pits will be paved soon.