[72projectbird]

Update:


Fuel pressure at the carb was hovering around 12psi. No good. So I start pulling off the rubber lines from the pump in anticipation of replacing the pump, and something caught my eye.

Turns out halfway up the rubber return hose was a chrome interior screw. After removing the hose, sure enough I couldn't blow through it at all. Totally blocked off.

When I got the car I blew all the steel lines out to make sure they were clear, but never checked the little rubber lines at the pump. The car arrived with a dead fuel pump, which I'm now suspecting had its life cut short by this clogged return.

After running a new rubber return, I pulled all the plugs and spun the motor over to clear out the flooding that took place. It now runs like a swiss watch.


So in short, dont be an idiot like me and assume the new looking rubber lines at the fuel pump are actually good.



Btw the pump I'm using is a Carter M6122 deep can with the return line.

[Shiny]

Sounds like a happy ending. Glad you got it resolved!

I'll note your success with that Carter pump if I decide to replace mine.

[78w72]

another option for a higher flow mech pump is the edlebrock, its probably the same design as the carter or holley high flow pumps & is rated at 6psi. i used one on my 467 stroker engine, it ran fine on the street & supported just under 520hp on the dyno when the engine was brand new, only did a few pulls for break in & to verify no leaks so there was no tuning, the dyno guy/engine builder did note it was starting to go lean so pulls stopped around 5600-5800 rpm.

https://www.summitracing.com/parts/edl-1713

[Formulajones]

Engine Masters did an episode quite a while back on cheap fuel pumps of various types that was pretty interesting. Season 4 episode 50.

Here's a short clip that's pretty funny

https://youtu.be/N8G2NA5JCx4

The whole episode has some pretty interesting thoughts once they finally get into fuel pumps that start keeping up with even this mild 500hp sbc.

[dhcarguy]

Is there a fuel pump that has just 4-5 psi needed for tripower cars?

[77 TRASHCAN]

Originally Posted by dhcarguy

Is there a fuel pump that has just 4-5 psi needed for tripower cars?

ANY stock replacement pump SHOULD meet that spec.

72Pb,
Now that it's running, we need pictures!!!

[Formulajones]

Yep, if you run a gauge you'll find that these stock replacement pumps will only hold 4-5 lbs at best. Especially once everything warms up.

They tend to hold a pound or so more when cold but will drop off once you build some heat.

The one example I posted above only had 3-4 psi cold and once it warmed up it dropped to ZERO

That's why I've said for a long time, even in very mild performance applications it's just better to "over fuel pump" the car and regulate it down. Way more consistent fuel pressure across the board hot or cold.

[jhein]

Now this has me wondering if my pump contributed to my less-than-expected Dyno results?? And if so, how bad is the lean condition for my motor?

[Formulajones]

What type of dyno?

Engine dyno will always have more than enough fuel supply, usually equipped with a pretty big electric pump and regulator to run most any engine.

Chassis dyno is a different story. It's what ever fuel system you've equipped the car with. Fuel line size also plays a roll.

[jhein]

Originally Posted by Formulajones

What type of dyno?

Engine dyno will always have more than enough fuel supply, usually equipped with a pretty big electric pump and regulator to run most any engine.

Chassis dyno is a different story. It's what ever fuel system you've equipped the car with. Fuel line size also plays a roll.

Engine. But I'm virtually certain he was running my mechanical pump. Now, that may have been fed by another electric I suppose.

[Formulajones]

It would be rare to run an engine dyno with the mechanical pump on the engine supplying the fuel, unless it was requested or something. Not unusual to have the mechanical pump in place however, just not hooked to anything.

Dyno cells have their own fuel supply so that potential fuel delivery problem is removed from the equation.

Did you video it? Possibly go back and look? Or call the dyno facility and hope they remember?

Are you trying to run a stock pump on a bigger HP application??

[jhein]

Originally Posted by Formulajones

It would be rare to run an engine dyno with the mechanical pump on the engine supplying the fuel, unless it was requested or something. Not unusual to have the mechanical pump in place however, just not hooked to anything.

Dyno cells have their own fuel supply so that potential fuel delivery problem is removed from the equation.

Did you video it? Possibly go back and look? Or call the dyno facility and hope they remember?

Are you trying to run a stock pump on a bigger HP application??

Here's a pic from the dyno session. It's definitely going through the mechanical pump. Based on my combo I was expecting to be around 500 hp.

[72projectbird]

Originally Posted by 77 TRASHCAN

ANY stock replacement pump SHOULD meet that spec.

72Pb,
Now that it's running, we need pictures!!!

It's the primer one in the middle of the pic. A fellow member (81 Black Bird) actually posted it in here for sale for his friend. It came from GA, and was a huge help in coordinating the sale.

I'm absolutely in love with it. Zero rust. Those southern guys are soooooo spoiled with their solid cars!

I've started detailing the engine bay. Still have lots to do, but it's coming along.

[Formulajones]

Originally Posted by jhein

Here's a pic from the dyno session. It's definitely going through the mechanical pump. Based on my combo I was expecting to be around 500 hp.

Well you at least have what looks like the Holley or Edelbrock type of mechanical pump. Those are typically rated around 110 gph.
A fuel pressure gauge mounted where you can read it while driving at WOT will quickly tell you if things are sufficient or not. If not equipped I usually tap into the line and run a temporary rubber hose through the cowl and tape the gauge to the windshield for a quick test around the block.

Honestly though, when I look at that pic, I see an aftermarket block, aluminum heads, and I'm guessing probably a decent size roller cam. Don't know the size of the engine but even a 455 is capable of an easy 500hp with those parts even breathing through stock RA manifolds. If you're running 500+ cubes I cringe at that mechanical pump, lol. If it's still pulling through stock size lines and a stock pickup in the tank the pump is somewhat handicapped anyway.
I can tell you from my own experience trying to make these cars fast with stock parts, that the stock mechanical fuel pumps with stock lines will only get you to about the 400-450hp level before they start showing fuel delivery problems. At that point I've had to upgrade something in the fuel system.
Since you have what looks like an aftermarket (bigger better) mechanical pump you're probably doing a little better than that but to be honest, at your power level I typically bypass mechanical pumps all together and put a big electric pump in a baffled tank and run 1/2" lines to and from. Then you never have to worry about it.
On cars like yours I typically hide the regulator where the mechanical pump normally rides, and then run stock steel line from there to the carb to keep a factory appearance.

[72projectbird]

Here's the current bird situation. They've taken over garage #1.

From left to right:
78 Y82 W72
77 W72
77 Y82 W72 4 speed

The poor Grand National has to sit on the lift for a little while.

[78w72]

Originally Posted by jhein

Here's a pic from the dyno session. It's definitely going through the mechanical pump. Based on my combo I was expecting to be around 500 hp.

my 467 was engine dyno'd with the mech pump too, most motors this builder does on his dyno he uses the customers mech pumps/carb/headers etc to get accurate numbers of what their engine will do as opposed to using an in house pump or carb that isnt what the car will use... unless they dont have a carb or other parts at the moment & want to use the dynos pump or carb etc.

i followed some of your posts, what hp/tq numbers did it do on the dyno? based on the parts i would have guessed above 500hp too. keep in mind, dynos can be all over the place, not as bad as wheel dynos but still variations in numbers. also an engine being brand new & not fully broken in makes a difference too.

my 467 with O-port E-heads, OF cam & SD ported factory intake with a cliff q-jet did a few hp under 520hp & right at 580tq when new using the edelbrock pump. the car ran 12.2 first time out on a few shake down runs but had pretty bad starvation issues, i changed to a robbmc pump & it does low 11's all day long, but still has random starvation issues on some good launch runs. those times & MPH of 121-123+ indicate the engine has more than 520 based on some calculators ive used. the car has bad traction/launch issues being its more set up for road racing than drag strip use.

point being im sure your engine is capable of more than 500hp or on a different dyno would have shown higher numbers.

[Formulajones]

The dyno sheet would give clues as to how the fuel supply was during the run. Your dyno operator should have been monitoring that. BSFC, lbs per hour of fuel, an AFR gauge, shucks he should have had at a minimum a fuel pressure gauge on there to see what it was doing.

I could see it working better on a dyno cell setup than in the car too, so the results for comparison aren't something I'd consider. He probably just has a short 3/8 hose running to a tank of fuel in the cell. Once in the car it has to pull through the pickup with a sock, and then 20 feet of 3/8 steel line with a couple dozen bends in it and what ever else you might have in the line.

[78w72]

for mine it was just put on the dyno for a quick break in & to verify no leaks, it wasnt a paid for dyno day that would have had all the sensors hooked up & some tuning done, it was literally just some run time to warm it up & 2-3 quick pulls to see what it did. this dyno is know to be pretty stingy.

the real world proof was at the track which i was very happy with the times considering the car isnt dialed in at all.

[Formulajones]

Ooops sorry, that post was meant for Jhein.

Honestly, his situation would need some testing with a gauge because I'm not 100% confident that Holley or Edelbrock 110 gph pump will do the job sucking through stock lines. A RobbMC might work a little better with it's larger body, especially the bigger version dialed back with a regulator, but honestly on a build like that with all the effort and it's HP potential I'd have 1/2" lines on it and a good electric pump in a baffled tank and call it done.

[jhein]

Originally Posted by Formulajones

The dyno sheet would give clues as to how the fuel supply was during the run. Your dyno operator should have been monitoring that. BSFC, lbs per hour of fuel, an AFR gauge, shucks he should have had at a minimum a fuel pressure gauge on there to see what it was doing.

I could see it working better on a dyno cell setup than in the car too, so the results for comparison aren't something I'd consider. He probably just has a short 3/8 hose running to a tank of fuel in the cell. Once in the car it has to pull through the pickup with a sock, and then 20 feet of 3/8 steel line with a couple dozen bends in it and what ever else you might have in the line.

Sorry to 72PB for the hijack, BTW...

Tell me what you can see from the Dyno sheet. It does have BSFC and fuel pressure. When I was picking al my parts, lots of people here said I'd probably have to upgrade my fuel delivery system, so I'm not really surprised. On Dyno day I did ask my builder if he thought the pump was a problem and he said no. But as you say, it wasn't in the car with 20 feet of 3/8 line to pull through. I also talked to Wayne at BOP and he verified that is his pump. It's not a holley or Ebrock, it's some other brand, but it's supposed to be 120 gph and 6.5 psi.