Had a problem at the track this weekend. Only got 2 make 2 passes due to some sort of mechanical issue. First pass car nosed over at the 1-2 shift and lost almost all power the rest of the track. LM unit showed it was super lean, in the 17s. Only had a very short time to be back in the lanes for eliminations, so I went up 10 jet sizes in the rear. Car pulled very hard the first 500 feet or so. Picture shows I have daylight under the left front!! So that is good...In any case, around the 500 foot mark, car loses all power, let off after the 1/8 cuz no way I was going to catch my opponent. I thought I had hit record on the LM unit, but hadnt...

Did a flow test and it pumps a gallon in 30 seconds,(Mallory 140, w Mallory dead head reg) so that should be OK. Pulled a few valve springs and they are fine.

Im still leaning towards a fuel delivery issue?

2nd pass motor didnt pop and crack like it was lean, just nosed over.

I have a Crane HI-6 box and Crane coil. Is there a good way to test the box?

I'll put it back together tomorrow, take it out and see if it will nose over again. I'll make sure and watch the LM if it does.

In the meantime, any tips on where to look next?

Did the car take off when you backed off the throttle?

Check the float levels if its got a carburetor(s).

I learned that day that fuel pressure and fuel volume are two different things.

What size carb. and needles and seats? As already said, fuel pressure and fuel delivery are not the same

Have you raced the car before like it is currently set up, or was this the first outing with it?

I had similar symptoms few years back with my old car.
Thought it was vapor locking, thought carb, blah, blah, blah.
Ended up being the 6al box was bad. Finally replaced it with a digital 6 after chasing the problem most of a summer.
Mine would run fine in first gear, but all the way through second and third it would miss and sputter, slowed it from 10 flat to 10.50 or so staying in it.
Mine would run fine one pass. Then maybe two passes it would act up, then run fine again
Made it a stinker to bracket race with... Lol

whats the fuel pressure going down the track? sounds like not enough pressure, had a similar problem, at top end of track car would die, got a fuel gauge and mounted on cowl, hardly no pressure down the track...

1. did you check your flow rate before the regulator or after?
2. what fuel tank is in your car, and what was the fuel level when you were racing?
3. where is your fuel filter located if you have one? And what type is it?

I once had a shift light that was shorting and cause the box to mess up, and the car would nose over at the shift points ??? It took a loooooooooonnnnnnnnng time to fine that one, let me tell ya...

Von, be patient, keep it simple. Sometimes it's more a matter of eliminating what it isn't.

How big a fuel line?

How much rubber/braided fuel line do you have?
I've had them collapse

If it's free, have the battery checked under load. Go to a place that specializes in batterys, like an Interstate distributor, or else Auto Irishman Parts Zone et al will tell you need a new battery.

You have just a bung with no sump? Any pics? What filter specifically, and what element?

Seeing that nobody mentioned yet, I will. Check your tank vent. It could be too small or partially plugged. You could always add another vent off your filler neck if needed.
My dodge now uses a ½ inlet vent because off similar issues.

Well knowing that you have a bung with no sump I'd say fuel slosh is definitely a possibility. Sounds like filter is not your issue, however I ask because I once had a -8 earls filter between pump and regulator cause me problems.

It was a sintered bronze type element and it was mounted on the frame. After driving a while (noticeably at freeway speeds) I could see my fuel pressure drop to almost nothing (had in-car fuel gauge). Turns out the element was getting hot from the exhaust and actually closing up. When the car was cold it wasn't an issue. Replaced it with a screen element and no more problem.

Hope you find what the issue is, a fuel pressure gauge (even a makeshift setup) that is readable from the drivers seat is invaluable .

if you pre filter the pump, nothing smaller than 100 micron would be my suggestion.

If you have a 10-50 it may cause restriction.