[Navy Horn 16]

Originally Posted by ta man

The fuel system may be costing you power at the track. I had the same fuel system years ago stock lines Holley Blue..I picked up almost 4mph in total going to a half inch pickup, Mallory 140 and all 8an lines.

Were you running out of gas? I had that issue when I had the engine driven pump. It would fall on it's face right at the 1-2 shift because the Q-Jet would essentially be dry. I haven't had any of those issues since upgrading to the blue.

[ta man]

Originally Posted by Navy Horn 16

Were you running out of gas? I had that issue when I had the engine driven pump. It would fall on it's face right at the 1-2 shift because the Q-Jet would essentially be dry. I haven't had any of those issues since upgrading to the blue.

Mine only fell on its face bad at the end when the blue pump was shot. I did a lot of passes that year with the blue pump and before it failed it felt ok at the track. I was still tuning the new head/cam combo and was 8 tenths and 8 mph quicker and without a in car fuel pressure gauge I didn't know I had fuel delivery issues since the car seemed fast. I'd have to look at my timeslips but from memory the Mallory 140 picked up 2 or 3mph over the previous best mph immediately and a little more after the bigger lines were installed.

[Navy Horn 16]

That's interesting. I'll keep an eye on it for sure. I'm running out of upgrades to do, so a little plumbing would be easy.

[Cliff R]

When I did the last upgrade to the fuel system in my car it had been running in the 12.40-12.60 range around 108-109mph.

The very next outing it went 12.0's at 112mph with no other changes.

Before the fuel system improvements the carb never ran completely out of fuel nor did the car "nose over", but it sure didn't pull like I though it should past about 5200rpm's or so.

On the very first pass with the new fuel system the engine spun past 5500rpm's so fast I didn't get the shifter moved quick enough and over-revved it!

I'd add here that before the fuel system upgrades I tried a Holley 850 DP carb with bigger fuel bowls and it didn't run any quicker than the Q-jet. After the changes it ran about the same as the Q-jet everyplace. Moral of that story is no matter what type of carb you are using, take steps to keep it FULL on hard runs if you want to see full potential from it.....FWIW.....Cliff

[Navy Horn 16]

Cliff,

What pressure do you run on your race set-up Q-Jets.

[taalltheway]

I don´t want to spoil the party but your 400 hp to the wheels sounds a bit low to me considering your big cam and 320 cfm-heads. Why am i saying this? My 74 SD455 was dynoed with the original low compression heads and small 224/230 rollercam with 382 hp at the rear wheels. OK, i have a manual Tremec transmission that costs less power than an automatic but still i would guess that there is a lot more in your combo. I would agree with everyone here that setting the timing and the carb on a dyno could work wonders. In my case we picked up 60 hp! I mean it ran well but the engine builder had set everything very conservatively.....of course he wants his engine to last long after warranty and as long as the customer does not complain why not play it safe?....it is crazy what a difference especially the timing makes...