Will my Carter 6903 120 gph mechanical fuel pump be sufficient for my 650 hp 528 hemi? I have driven it some on the street so far so good.(just got it done in the fall) I've done a couple blasts threw the gears no stumbles,but I have not run a full quarter mile shot yet. The car is a street car with 3/8 fuel line no return line and factory dual 4bbl 5/16 lines at the carbs. anyone else running similar power with a mechanical pump?

I've about the same set up, the motor was dynode with the mech pump and didn't stumble. Give it a shot and let us know.

I'd see what the psi is at the carb inlets at the end of the quarter (want several psi). Wouldn't want to leave it that way but for 1 quick test you could T at the carb inlet(s) & run a line in to a gauge in the dash & see what you have. Wouldn't pass tech but could do it on a deserted street . & if delivery is adequate & if still lean you might be able to tap the other side of the AFB air horn to make a dual feed inlet

i am running (i think) the same pump, but haven't tried it yet. i have a 3/8" setup to go to the 5/16" tee, and then 5/16"lines to the carbs.

but then i saw a picture of a 572 fresh off of the dyno at tim bannings shop, and it had 5/16" from the pump up. tim had also told me earlier the 5/16" will handle it just fine. i'm assuming the pump is no issue here, although he uses the edelbrock with a regulator tied to the pump.

i'm going to start out with the 5/16" and see from there...

Sounds good. I hope I can leave this setup in place. I'm just cautious about ever leaning this thing out. Barton's used their electric pump on my dyno pulls. The engine is scary fast so far. It hasn't missed a beat with the mechanical pump. but I haven't run it out the back door yet.

there is a lot of talk about at least 3/8" line, electric pumps and all kinds of stuff, but my 472 with 5/16" line and the wimpy carter pump never had an issue.

tim's 572's dyno at 750hp with 5/16" lines, so something is working right there!

Your engine burns, at the most, 40 gph. I think the pump will work fine.