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55 Tony
01-27-2018, 01:16 PM
The other day I was doing a 1/4 mile and at around 90mph it started loosing power. This was not at all like previous problems where when hot, it gets vapor in the system and it REALLY dies but responded to pumping the pedal, that came back again. This problem was more like it just stayed at 90 for a few seconds then picked up again. I don't know if I'm explaining that very well?

Anyway, today I revved the engine a little and watched the fuel pressure and it dropped every time I revved it. Actually it pulsed from close to zero up to near 5 when revving it. At idle it pulsed from about 5 to 6psi. When I clamped the return line it did the same, and it held pressure after stopping the engine. I had another holley fuel pump (used) and went to install it but I over tightened the one fitting and cracked the pump. Both are Holley 12-454-11 pumps. Question is ... do I really need a Free Flow Rate of 110 gph?

I did take them apart and try to make one good out of the two but the casting that cracked is the one with 3 check valves, and I'm not so sure of popping them out and swapping the casting, they are not made to be rebuilt.

So do I really need a 110gph free flow pump? HP estimates were around 450.

55 Tony
01-27-2018, 01:34 PM
I just read somewhere about an engine running out of fuel and a lightwhight push rod cured it. I'm shifting at 5500rpm, don't know if a hollow push rod is needed?

Rick_L
01-27-2018, 02:55 PM
A friend has that pump on a 502 that made 525 hp at the rear wheels (with a bad tuneup). Should work fine for you if everything is working right. You should not need a lightweight push rod.

FWIW he had some fuel pressure problems when he first put the 502 in it, replacing a 454. Turned out it was not the fuel pump. He had one of the "new" Holley carbs on it, piece of junk. Put his old 750 and old regulator back on, all was good.

55 Rescue Dog
01-27-2018, 04:04 PM
Starting witht the inlet, and fuel line would be a good thing to verify first. Hard to suck fuel through a restriction. Fuel pump rod is not the issue. The 427 I once had 45 years ago could fly at 7000 rpm with OE stuff. I had 2 different 427's machined at Speed-O-Motive in West Covina, California, with cams custom ground at Sig Erson in Long Beach, when I was in the NAVY 72-76, and they performed perfect. I loved it back in the day out there when there was speed shops everywhere, blocks away! Now it has been replaced by amazon...

chevynut
01-27-2018, 06:16 PM
110 GPH is way overkill for 450 HP. You only need around 38 GPH. Pull your tank pickup and make sure there's no junk on it or in your tank. If you only have a 5/16" pickup I'd recommend going to a 3/8" one and increasing your line size to 3/8" all the way to the pump.

"There’s a simple formula to calculate GPH or LPH (liters per hour), but there are some variables to this formula, depending on your application. Norm Koval, a team leader in the Summit Racing technical department, typically follows this formula as laid out by the air/fuel experts at Holley:


Optimal GPH = (Max. HP x BSFC) / 6
Optimal LPH = (Max. HP x BSFC) / 1.585
In order to make the proper calculation, you need to determine your variables for this equation, starting with your vehicle’s maximum horsepower (Max. HP).

The second variable in the equation is BSFC, or brake-specific fuel consumption. BSFC is a measurement of the amount of fuel consumed per unit of power produced. According to Holley (http://www.summitracing.com/search/brand/holley), an engine typically requires .5 pounds of fuel per horsepower every hour at wide open throttle. However, this number generally applies to naturally aspirated engines."

55 Tony
01-27-2018, 06:41 PM
I was looking at lightweight push rods and then it hit me about the special rod for the roller cam and forgot what I used so I took it out and yes it is a lightweight with a bronze I believe tip for the cam, whew! I did put the pump back together and well it's the same as it was so I don't know what is going on with it yet. I have a quadrajet on it right now but also have an old Holley 800 spreadbore with mechanical secondaries. Only problem with that was the way the bowls hang out the fricken gas we have here boils on warm winter days and the summer gas boils on hot summer days. The Q-jet keeps the fuel cooler the way the bowl is in the middle. And yes I have a 1" spacer and both crossovers in the manifold blocked 100%. I wish they made an air gap spreadbore manifold for a BBC.

55 Tony
01-27-2018, 06:49 PM
I have 3/8 line from the pickup to the carb. When I pulled the return line off it kept spewing fuel so I put the air hose to it lightly and while I heard the hissing of air from the fuel cap, it also suddenly shot gas out the pickup line so I think that is clear. The tank is only about 5 years old and has been drained a couple times so I don't worry too much about dirt in there.

Rick_L
01-27-2018, 06:49 PM
If you have a "boiling" problem it is at rest, most critical when the engine is first shut off. If really bad, it might affect idle and cruise. But it won't affect WOT operation. Fuel doesn't have a chance to heat up at WOT. Not only that, with a carb there is self cooling at WOT.

Are you monitoring fuel pressure real time? Or only at idle with a temporary gauge?

chevynut
01-27-2018, 07:12 PM
Is this a new problem, and did the car run fine at 90+ MPH before?

What "return line" are you referring to? Are you running a regulator? Holley says you don't need a regulator with that pump. Also, you said you have a 3/8" line "from the pickup"....is the pickup itself a 3/8" one inside the tank?

I had a 55 Chevy with a '67 Corvette 390 HP 427 in it and it would starve for fuel at high RPM....similar to what you're describing. I used the stock mechanical fuel pump with the stock 5/16" line and I'm pretty sure the line was the problem. It needs to be clear all the way to the pump with no restrictions. Make sure you don't have any restrictive fittings in the lines.

55 Tony
01-28-2018, 03:50 AM
If you have a "boiling" problem it is at rest, most critical when the engine is first shut off. If really bad, it might affect idle and cruise. But it won't affect WOT operation. Fuel doesn't have a chance to heat up at WOT. Not only that, with a carb there is self cooling at WOT.

Are you monitoring fuel pressure real time? Or only at idle with a temporary gauge?

The old "running out of gas" problem has always, always, always happened when the temperature was high. It became *practically* non existent when I installed a filter with a bypass as close to the carb as possible.
The boiling over at first happened while driving when the ambient temp was very high, then after adding the spacer and blocking the crossovers it stopped with the quadrajet but still did it at times with the holley after it was turned off, I believe only from the secondary bowl.

There is a permanent gauge on the regulator, so no I can not monitor it while driving. Do people run them inside like a oil pressure gauge?

55 Tony
01-28-2018, 03:59 AM
Is this a new problem, and did the car run fine at 90+ MPH before?

What "return line" are you referring to? Are you running a regulator? Holley says you don't need a regulator with that pump. Also, you said you have a 3/8" line "from the pickup"....is the pickup itself a 3/8" one inside the tank?

I had a 55 Chevy with a '67 Corvette 390 HP 427 in it and it would starve for fuel at high RPM....similar to what you're describing. I used the stock mechanical fuel pump with the stock 5/16" line and I'm pretty sure the line was the problem. It needs to be clear all the way to the pump with no restrictions. Make sure you don't have any restrictive fittings in the lines.

I believe it is a new problem. But it did happen on a warm day with winter gas, just not as bad as before. The pickup is 3/8. I don't know what it is here, no one else in other area's has fuel that boils so easy.

55 Rescue Dog
01-28-2018, 04:39 AM
The old "running out of gas" problem has always, always, always happened when the temperature was high. It became *practically* non existent when I installed a filter with a bypass as close to the carb as possible.
The boiling over at first happened while driving when the ambient temp was very high, then after adding the spacer and blocking the crossovers it stopped with the quadrajet but still did it at times with the holley after it was turned off, I believe only from the secondary bowl.

There is a permanent gauge on the regulator, so no I can not monitor it while driving. Do people run them inside like a oil pressure gauge?
Running a fuel pressure gauge would be a good idea, but not inside the car unless you have an pressure isolator, or an electric sender.

55 Tony
01-28-2018, 05:36 AM
Running a fuel pressure gauge would be a good idea, but not inside the car unless you have an pressure isolator, or an electric sender.

I'll have to look at Summit. Never saw either one of those, that's why the gauge is under the hood!

chevynut
01-28-2018, 05:57 AM
I agree with Rick, your fuel isn't going to boil at WOT and that's not your problem. I would at least temporarily plumb a fuel pressure gauge into the car so you can watch it and see if the pressure drops off when the engine loses power. Personally I wouldn't worry about plumbing a temporary fuel line into the car using the appropriate fittings and a rubber fuel line for troubleshooting. You're not running high pressure so the safety risk is low. For a permanent installation I'd use an electric fuel pressure sender and gauge. If the pressure drops off when the engine starts to die at high RPM, I'll bet you either have a bad pump or a restriction in the line between the pump and tank. If it was me I'd be using an electric pump at the rear of the car and ditch the mechanical one. It's better to push fuel than to suck it.

55 Tony
01-28-2018, 08:03 AM
I believe the only time pushing fuel is easier than pulling it, is when the line has air in it. Once primed the mechanical pumps work just fine.
I might hook up a temporary gauge like you say, if I can find the right fittings. I think I may tape it to the outside of the windshield. Then wait a day or two till the rain stops.

chevynut
01-28-2018, 08:51 AM
I still don't understand what "return line" you're referring to and what the "filter with a bypass" that you mentioned is.

With a mechanical pump you will ALWAYS have suction in the supply line between the pump and the tank. If you pull enough of a suction on the fuel line, due to a high volume pump and a restrictive line between the pump and the tank, you can cause vapor lock in the fuel line under the right conditions. For example, if the pump is trying to supply the carb at the 38 GPH you're burning it (at 450 HP) but it's pumping at full capacity and the regulator is bypassing the remainder of the 110 GPH of fuel pumping capacity back to the tank, the supply line may not be able to supply enough fuel and the pump is pulling a vacuum on the line. If it pulls enough of a vacuum, it can cause vapor lock or at least a drop in fuel pressure.

"Vapor lock was far more common in older gasoline fuel systems incorporating a low-pressure mechanical fuel pump (https://en.wikipedia.org/wiki/Fuel_pump) driven by the engine, located in the engine compartment and feeding a carburetor. Such pumps were typically located higher than the fuel tank, were directly heated by the engine and fed fuel directly to the float bowl inside the carburetor. Fuel was drawn under negative pressure (gauge pressure (https://en.wikipedia.org/wiki/Gauge_pressure)) from the feed line, increasing the risk of a vapor lock developing between the tank and pump. A vapor lock being drawn into the fuel pump could disrupt the fuel pressure long enough for the float chamber in the carburetor to partially or completely drain, causing fuel starvation in the engine. Even temporary disruption of fuel supply into the float chamber is not ideal; most carburetors are designed to run at a fixed level of fuel in the float bowl and reducing the level will reduce the fuel to air mixture delivered to the engine."

Here's some info on fuel line sizing. http://fuelab.com/fuel-line-size-vs-pressure-drop/

You mentioned a return line before so I believe you must have a regulator plumbed in. Since the Holley pump doesn't need a regulator (according to Holley) I would remove it so it doesn't bypass fuel back to the tank. That just makes the pump work harder, pulling more fuel through the fuel supply line.

http://documents.holley.com/fuel_pump_tech_info.pdf

"110 GPH pumps are designed for street/strip applications where substantially higher than stock fuel delivery requirements are necessary. 3/8" inlet and outlet ports are utilized and, with fuel shut-off pressure in the area of 6-1/2 - 8 PSI, a regulator is not required."

So if your regulator is set at 5 psi you're always bypassing fuel to the tank making the pump draw more fuel through the supply line.

55 Tony
01-28-2018, 09:48 AM
https://www.autozone.com/filters-and-pcv/fuel-filter/duralast-fuel-filter/830813_0_0
When I installed the above filter and ran a return line back to the tank, the "running out of gas" symptoms that were common in summer temps above 80F disappeared but did return not as bad in temps above 90F. The filter is made so if there is any vapor, it floats up to the return part of the filter. The outlet to the carb is down lower so it gets liquid. This filter has to be installed in at least partially upright position with the bypass at the top to function properly.

Now I will say again, after running the return line, the vapor problem got much, much better, not worse. The filter above is plumbed in about 1.5" before the carb to minimize the area for more vapor to form before getting to the carb.

chevynut
01-28-2018, 11:52 AM
https://www.autozone.com/filters-and-pcv/fuel-filter/duralast-fuel-filter/830813_0_0
When I installed the above filter and ran a return line back to the tank, the "running out of gas" symptoms that were common in summer temps above 80F disappeared but did return not as bad in temps above 90F. The filter is made so if there is any vapor, it floats up to the return part of the filter. The outlet to the carb is down lower so it gets liquid. This filter has to be installed in at least partially upright position with the bypass at the top to function properly.

Now I will say again, after running the return line, the vapor problem got much, much better, not worse. The filter above is plumbed in about 1.5" before the carb to minimize the area for more vapor to form before getting to the carb.

Are you talking about two different problems? You've mentioned a "running out of gas" problem and a "vapor" problem. Sounds like one is at high speed/RPM and the other is at idle.

So you don't have a pressure regulator, and the "return" you're talking about is only the filter vent line and the filter has a constant flow of fuel returning to the tank?

Vapor lock is more likely to show up BEFORE the pump unless the line past the pump gets hot. After the pump the gas is under pressure and at the same temperature, the gas on the suction side of the pump will vaporize before the gas on the pressure side. The faster the engine is turning the more suction you get on the fuel line. The more suction, the more chance of vapor lock. The constant flow of gas back to the tank forces the pump to pump harder, creating more suction. If the fuel line is close to the exhaust, it will get hot and make the problem worse.

I don't see how the return line helps at high RPM at 90 MPH. I'd plug the return line and take it out again at high speed to see if it changes the problem. If not, I still say you have a restriction somewhere in the fuel line, if the pump is working properly. Or the fuel line ahead of the pump is getting hot.

http://www.camaros.net/forums/33-camaro-tech/199001-vapor-lock.html

55 Tony
01-28-2018, 02:03 PM
No both were at high rpm. Only problem I ever had at idle was fuel boiling over in the carb and stalling and flooding the engine. Basically I believe the constant flow of fuel normally keeps it from getting hot and vapor locking. From everything I've been through I believe that to be true. Maybe a pump back at the tank will help? I'm curious if anyone installed a vacuum gauge in the fuel line back at the tank to see how much vacuum there actually is. I did have the 3/8 line before the bypass and adding the bypass made the problem pretty much go away until now, and a few times when it was very hot. I'll go out and install the new pressure gauge I got and put it on the windshield and with any luck I'll be able to test it tomorrow with and without the bypass. Have to wait for dry roads.

Oops, got that wrong. If someone was to install a vacuum gauge on the fuel line, it would go directly before the pump, not back at the tank.

55 Rescue Dog
01-28-2018, 02:37 PM
No both were at high rpm. Only problem I ever had at idle was fuel boiling over in the carb and stalling and flooding the engine. Basically I believe the constant flow of fuel normally keeps it from getting hot and vapor locking. From everything I've been through I believe that to be true. Maybe a pump back at the tank will help? I'm curious if anyone installed a vacuum gauge in the fuel line back at the tank to see how much vacuum there actually is. I did have the 3/8 line before the bypass and adding the bypass made the problem pretty much go away until now, and a few times when it was very hot. I'll go out and install the new pressure gauge I got and put it on the windshield and with any luck I'll be able to test it tomorrow with and without the bypass. Have to wait for dry roads.
Try to attach your gauge near the fuel inlet to the carb, or after the filter.

Rick_L
01-28-2018, 03:10 PM
Autometer has isolators for their fuel pressure gauges. https://www.autometer.com/media/2650-1124.pdf

The tee for the gauge should be as close to the carb inlet as possible.

I have to wonder if your return line installation is leaking from pressure to return.

55 Rescue Dog
01-28-2018, 04:57 PM
Don't forget the brass fuel filter too, used behind the fuel inlet fitting on most carbs.

Custer55
01-28-2018, 05:15 PM
Do you have any rubber fuel lines before the fuel pump that could be collapsing from the suction from the pump? Don't know if that's possible or not but I was reading something the other day that vacuum hose and fuel hose are different in that fuel hose resists pressure from inside the hose outward but not from vacuum collapsing it. Vacuum line works the opposite way.

55 Rescue Dog
01-29-2018, 06:16 AM
Pictures of your car/engine would help too. There are lot of variables not even knowing what you air cleaner set-up looks like, ignition, etc. How does the car handle/drive at 90mph, and where do you drive it?

markm
01-29-2018, 06:38 AM
I run an old Eldebrock Mech on my 396 with 1/2 inch inlet and outlet and 1/2 line all the way to tank which is the original 1955 tank with a rear facing sump. A Holley regulator splits the line to each Holley 600 on top of tunnel ram. No fuel starvation issues.

bigblock
01-29-2018, 07:20 AM
I would check the brass filter, did you check the float level and the needle and seats?

bigblock
01-29-2018, 07:26 AM
I would check the brass filter, did you check the float level and the needle and seats? I would make sure the rubber hose if any on the suction side is new, and I feel it is better to push fuel then suck it, it is easier to control the pressure.

Troy
01-29-2018, 07:29 AM
Hello Tony,

I've always had and heard that Quadrajet have problems with WOT and starving for fuel at extended WOT operation. My '55 has a quadrajet and while at school we had 1/4 mile drags and mine starved between the 1/8 mile mark and the 1/4 mile mark.

55 Tony
01-29-2018, 11:53 AM
I had a used pump, same as the current one, on the shelf. But while installing the fittings broke the housing. I took both apart and even though it's not made to be serviced, I had the valves out, got them mixed up, and put them in again. My pressure gauge now shows way less fluctuation at idle then it used to. It used to go from 3 to 5psi at idle, now it only goes from about 5.25 to 5.75, and up to 6psi as soon as it gets to 800 rpm.
Tried it today and it ran fine, in fact on my phone I ran a 1/4 mile app and my best run when I didn't spin the tires too much I did a 12.457. Other runs when I did poorly and spun the tires a lot were almost a second longer. Can't wait to try slicks! Actually I'm not sure of the accuracy of that 12.457. Could have been a glitch on that run.
The road I was on is a lightly traveled 4 lane divided highway and most of the time there were no other cars in sight.

Inside the q-jet is a fine screen filter in place of the paper one, it isn't dirty.

The current q-jet I'm running has a slightly larger bowl than my older one. I'd post a pic of the different bowls but I'm having pic problems. Also I use an oversize needle and seat to help keep the bowl full.

55 Rescue Dog
01-29-2018, 03:11 PM
Well, trying to run 12 sec quarters on lightly traveled roads is a good way to end up on the 6 o'clock news, and just plain irresponsible. Zero-60 runs in an isolated area is barely acceptable, and will tell you just as much as you need to know.

55 Tony
01-29-2018, 03:18 PM
I run an old Eldebrock Mech on my 396 with 1/2 inch inlet and outlet and 1/2 line all the way to tank which is the original 1955 tank with a rear facing sump. A Holley regulator splits the line to each Holley 600 on top of tunnel ram. No fuel starvation issues.

Are you serious ... 1/2"? At first I was running the original 5/16 and when I put in new 3/8 line and pickup I didn't notice any improvement with the fuel starvation problem. I've never seen a 1/2" pickup for our cars, just 5/16 and 3/8. I don't think I ever had any fuel starvation problems when running a Holley either with their large bowls. Q-jet is a different story.

55 Tony
01-29-2018, 03:32 PM
Well, trying to run 12 sec quarters on lightly traveled roads is a good way to end up on the 6 o'clock news, and just plain irresponsible. Zero-60 runs in an isolated area is barely acceptable, and will tell you just as much as you need to know.

Zero to 60 is barely acceptable? Even when the speed limit is 70 and I don't get anywhere near any other vehicle. Actually if you pass a state trooper doing 80 they don't bother with you. Yes another 35mph is a lot but I really don't see who it could hurt besides myself and how is it more safe at a track?

chevynut
01-29-2018, 03:36 PM
Zero to 60 is barely acceptable?

:D :D :D

55 Rescue Dog
01-29-2018, 03:37 PM
Zero to 60 is barely acceptable? Even when the speed limit is 70 and I don't get anywhere near any other vehicle. Actually if you pass a state trooper doing 80 they don't bother with you. Yes another 35mph is a lot but I really don't see who it could hurt besides myself and how is it more safe at a track?
Never mind, I give up, that all makes perfect sense with a 63 year old car. And at the track, they have emergency personal on site.

markm
01-29-2018, 04:44 PM
Are you serious ... 1/2"? At first I was running the original 5/16 and when I put in new 3/8 line and pickup I didn't notice any improvement with the fuel starvation problem. I've never seen a 1/2" pickup for our cars, just 5/16 and 3/8. I don't think I ever had any fuel starvation problems when running a Holley either with their large bowls. Q-jet is a different story.

I have a sender unit with the gas line blocked off, read my post again tank my tank has a custom rear facing sump with two 1/2 npt rear facing outlets. when I launch gas is forced toward tank outlet. As far as float bowls I have 4 of them to feed.

Rick_L
01-29-2018, 04:51 PM
The only reason a Holley would do better than an Edelbrock or Qjet is the float bowls hold a little more fuel. But not much more. You'll still run out of fuel in less than 1/4 mile if you have pump or restriction problems.

55 Tony
01-29-2018, 05:32 PM
I have a sender unit with the gas line blocked off, read my post again tank my tank has a custom rear facing sump with two 1/2 npt rear facing outlets. when I launch gas is forced toward tank outlet. As far as float bowls I have 4 of them to feed.

Yes, that info about the tank didn't sink in. And the split to two, I was thinking bowls, not carbs. I'm guessing you're only doing 1/8's, or awfully high speed 1/4's. What kind of times?

chevynut
01-29-2018, 05:54 PM
Never mind, I give up.

Good. Nobody asked for your safety lecture in the first place. :D

BamaNomad
01-30-2018, 06:41 AM
http://www.trifivechevys.com/images/misc/quote_icon.png Originally Posted by 55 Rescue Dog http://www.trifivechevys.com/images/buttons/viewpost-right.png (http://www.trifivechevys.com/showthread.php?p=43070#post43070)
Never mind, I give up.

Good. Nobody asked for your safety lecture in the first place. :D

You fellas MUST be brothers! Can't you just HUG and make up and pretend to be grown up??
All fighting brothers do it sooner or later...

markm
01-30-2018, 06:57 AM
VIDEO]https://www.youtube.com/watch?v=2mZLTTtDJZg[/VIDEO][/QUOTE]

I have only made passes at flag drags see link, the one time I showed up at a 1/4 mile track I lost the front yoke and u-joint on starting line. I have two purpose built Camaros that run 10s and 11s with minimal effort and just routine maintaince. My BBC Camaro has #10 or 5/8 fuel line from cell to regulator.

markm
01-30-2018, 07:05 AM
http://www.trifivechevys.com/images/misc/quote_icon.png Originally Posted by 55 Rescue Dog http://www.trifivechevys.com/images/buttons/viewpost-right.png (http://www.trifivechevys.com/showthread.php?p=43070#post43070)
Never mind, I give up.


You fellas MUST be brothers! Can't you just HUG and make up and pretend to be grown up??
All fighting brothers do it sooner or later...

Over the years I have known many who pick at everyone who is out cruising or racing talking how bad their project is going to be when it comes out. In fact I ran into one of them the other day and he offered to sell me his pride and joy 69 Camaro 10 inch tire full cage ultimate street strip machine. Its out of date and unfinished.

55 Rescue Dog
01-30-2018, 01:25 PM
Zero to 60 is barely acceptable? Even when the speed limit is 70 and I don't get anywhere near any other vehicle. Actually if you pass a state trooper doing 80 they don't bother with you. Yes another 35mph is a lot but I really don't see who it could hurt besides myself and how is it more safe at a track?
Sorry I was kind of thinking of an accident a week ago when 3 local kids were testing their tuner car going 85 in a 45, lost control, sideways into to a SUV, and they were turned into shrapnel, along with 90/% of their car scattered all over the road for many people to witness, and clean up in bitter temperatures. Something just as simple as tires under the conditions are always suspect too.

55 Tony
02-02-2018, 06:16 AM
Sorry I was kind of thinking of an accident a week ago when 3 local kids were testing their tuner car going 85 in a 45, lost control, sideways into to a SUV, and they were turned into shrapnel, along with 90/% of their car scattered all over the road for many people to witness, and clean up in bitter temperatures. Something just as simple as tires under the conditions are always suspect too.

Been busy working for a change ... anyway no big deal. If you saw the highway yourself you would probably *almost* let it slide.