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SlowRider
12-12-09, 11:27 AM
Hello,

Can anyone suggest where I should install my new Holley Red Electric fuel pump (97 gallons per hour)? It's feeding a RV8 with an Edelbrock 750cfm carb.

When I got the car, the previous pump was on the LHS of the boot, very close to the fuel tank. However, my mechanic installed it inside the LHS wheel well to "aid in cooling". I'm not fully convinced that this is the best way to go though.

Lastly, if anyone can suggest the fuel line sizes, that would be really great!

I'm writing from the Philippines so there aren't that many RAM Cobras around.

Thanks!

Anton

slogger
12-12-09, 11:57 AM
Hello,

Can anyone suggest where I should install my new Holley Red Electric fuel pump (97 gallons per hour)? It's feeding a RV8 with an Edelbrock 750cfm carb.

When I got the car, the previous pump was on the LHS of the boot, very close to the fuel tank. However, my mechanic installed it inside the LHS wheel well to "aid in cooling". I'm not fully convinced that this is the best way to go though.

Lastly, if anyone can suggest the fuel line sizes, that would be really great!

I'm writing from the Philippines so there aren't that many RAM Cobras around.

Thanks!

Anton
In the wheel arch is fine I would say. I tend to prefer not to have pressurised fuel inside the boot area. Need to make sure that you will not suffer with the tyre or road debris contacting the pump or fuel line.

On another note, why on earth are you running a 750CFM on a Rover V8? I have one of them, be it a Holley, on a 454 Chevy Big Block at 460 inch. 7.5 ltr!!!

Sidecarbod
12-12-09, 01:06 PM
I agree, you never get a 750 carb to work well even with the biggest RV8 you could build. :(

As to the pump, there is a formula that works very well as long as you know the BHP figure for your engine. (You can take an educated guess)

BHP=(CC of fuel per minute) divided by 4.7

Or

CC of fuel per minute must equal BHP x 4.7

If your 97 gallons per hour is US gallons then one US gallon is 3.78 litres. That means that the pump will flow 6.1 litres per minute. (That seems like a hell of a lot and makes me think that my figures are wrong! Or that the pump will deliver that but not by the time it has pumped it along the fuel line to the engine bay. :( )

My Stage III 4.6 makes about 285 BHP and therefore needs 1340cc of fuel per minute. I've tested my pump at the point that the fuel enters the carb and it flows about 1800cc of fuel per minute. :p

SlowRider
12-12-09, 01:42 PM
Whoa! The 750 carb does sound like overkill :roll: Thanks for the eye opener!

If you don't mind though, what is the effect of having an oversized 750 carb on the RV8? I'm new at this and the carb was the only one readily available here in the Philippines.

Going back to my situation, I live on an island called Cebu and we don't have any long sweeping roads so ideally, I do more short 1st, 2nd and (if lucky or crazy) 3rd gear bursts. I can't do sustained high speed runs here. Having said that, I'd prefer to have the car set up for more low end tractable grunt rather than top end BHP. Help! :confused:

Sidecarbod
12-12-09, 02:06 PM
Whoa! The 750 carb does sound like overkill :roll:

If you don't mind, what is the effect of having an oversized 750 carb on the RV8? I'm new at this and the carb was the only one readily available here in the Philippines.

Going back to my situation, I live on an island called Cebu and we don't have any long sweeping roads so ideally, I do more short 1st, 2nd and (if lucky or crazy) 3rd gear bursts.

Having said that, I'd like the car set up for more low end tractable grunt rather than going for top end HP. Help! :confused:

Hi There,

The effect of running an over size carb is that the motor will bog down badly when you floor the throttle, this is due to the fact that the vacuum in the carb will drop to nothing because the engine is just not big enough. Without vacuum the carb will not deliver any fuel so you get a lean bog.

Other problems would be that you night not even be able to calibrate the carb correctly, in other words you can not get the air/fuel ratio correct for all (or any) running conditions. If the A/F ratio is too rich you will lose power, foul the plugs, wash the cylinder bores, and waste fuel.

Even if you do get the A/F ratio right the quality of the mixture will probably be poor, you will have big blobs of fuel in the air stream because the air speed to too low, this is not good for a quick burn. Calibrating (re-jetting) a carb that is too big for the engine that it is fitted to can be very difficult because the carb just won't respond properly to any changes that you make. You might not even be able to jet hold of the correct jets and metering rods as they are not even manufacturered.

There is some tolerance with regards to the size of the carb, within limits you can go slightly too large to gain some top end performance at the expense of low end grunt but there are limits to this. (Not to mention the restriction of the sizes of available carbs).

The driving conditions that you have described definitely won't suite even going slightly too large on the carb!

If I was you I'd sell the 750 carb and buy a 500 off the web, then it should not matter where you live.

The 500 carb will require a small amount of re-calibrating which I can help you with. This carb will work very well with a stock 3.5 RV8 or a 5.0 RV8. If you go down this route let me know so that I can suggest some rods and jets that you could buy at the same time.

Personally I prefer the Eddy carb to a Holley carb, but that just my humble opinion!

Have a read of this:-

How To Build a Pilgrim Sumo: Fueling System (http://how-to-build-a-pilgrim-sumo.wikidot.com/fueling-system)

Other mods to the 3.5 RV8 that are worth doing are to do with the ignition system (the ignition timing). There is a huge amount of low end grunt that is lost when you set the ignition up the way that Rover tell you to set it up!


I'm assuming that you have a 3.5!...some info on your engine would be useful!

blip
12-12-09, 06:55 PM
Hi Anton,

I'm guessing you're the guy I was chatting with on You Tube?

If so, did you get the info I sent?

Phil.

SlowRider
13-12-09, 09:08 AM
Hi Phil,

It's a small world, you were chatting with my brother, Ezra. He forwarded me your info, thanks a bunch for that and it's great to see you here! This cobra is a "family" car we all share with my dad and two brothers given that it's the only running cobra in town. For the forum though, I use "I" instead of the royal "we" :D.

We're still guessing it's a turnkey early 90s RAM (with a 5 digit VIN), 3.5 RV8, 5 speed unknown tranny, smiths gauges and quad shock IRS potentially from a jag donor. I'm confirming it now with Realm Engineering, hopefully they'll still have some info on this unit.

Shortly after we got the cobra running, we know for a fact that there are now at least five other guys assembling their own kits as we speak. Not bad for a small island of 3.5M inhabitants, will keep you posted on the potential Cebu Cobra Club brewing.

I look forward to more exchanges in the future. Cheers!

Anton

SlowRider
13-12-09, 11:05 AM
...If I was you I'd sell the 750 carb and buy a 500 off the web, then it should not matter where you live.

The 500 carb will require a small amount of re-calibrating which I can help you with. This carb will work very well with a stock 3.5 RV8 or a 5.0 RV8. If you go down this route let me know so that I can suggest some rods and jets that you could buy at the same time.

Personally I prefer the Eddy carb to a Holley carb, but that just my humble opinion!

Have a read of this:-

How To Build a Pilgrim Sumo: Fueling System (http://how-to-build-a-pilgrim-sumo.wikidot.com/fueling-system)

Other mods to the 3.5 RV8 that are worth doing are to do with the ignition system (the ignition timing). There is a huge amount of low end grunt that is lost when you set the ignition up the way that Rover tell you to set it up!


I'm assuming that you have a 3.5!...some info on your engine would be useful!

Hi Sidecarbod,

Thanks for the help, your info on the carb theory for our 3.5 RV8 is really helping us narrow down the cause of our (willful) woes :D

I've had problems with plugs fouling up and the engine running sweetly with a great off idle pull up to mid throttle for only just a few days then either experience severe hesitation or get stranded by the roadside (again).

My dad and I have been focusing on just getting fuel to the engine because we've "burned" through 3 tiny japanese fuel pumps before finally deciding on the red holley elec pump (that's why the thread started with fuel pump location). When we bought the car, it also had really small japanese pump located in the Front LHS of the engine bay! Needless to say, it didn't run well for very long.

I'll update you as to when we'll change the carb to a 500 Eddy. It does look like the over carb scenario will be keeping us in the garage more than out there on the road.

All we've been experiencing lately is sweet running for a few hours then hesitation city after that!

sharonk868
06-01-10, 10:30 AM
Hello,

Can anyone suggest where I should install my new Holley Red Electric fuel pump (97 gallons per hour)? It's feeding a RV8 with an Edelbrock 750cfm carb.

When I got the car, the previous pump was on the LHS of the boot, very close to the fuel tank. However, my mechanic installed it inside the LHS wheel well to "aid in cooling". I'm not fully convinced that this is the best way to go though.

Lastly, if anyone can suggest the fuel line sizes, that would be really great!

I'm writing from the Philippines so there aren't that many RAM Cobras around.

Thanks!

Anton
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Sidecarbod
06-01-10, 11:57 AM
Hi Sidecarbod,

Thanks for the help, your info on the carb theory for our 3.5 RV8 is really helping us narrow down the cause of our (willful) woes :D

I've had problems with plugs fouling up and the engine running sweetly with a great off idle pull up to mid throttle for only just a few days then either experience severe hesitation or get stranded by the roadside (again).

My dad and I have been focusing on just getting fuel to the engine because we've "burned" through 3 tiny japanese fuel pumps before finally deciding on the red holley elec pump (that's why the thread started with fuel pump location). When we bought the car, it also had really small japanese pump located in the Front LHS of the engine bay! Needless to say, it didn't run well for very long.

I'll update you as to when we'll change the carb to a 500 Eddy. It does look like the over carb scenario will be keeping us in the garage more than out there on the road.

All we've been experiencing lately is sweet running for a few hours then hesitation city after that!


I'm sure that you will end up getting it sorted.

If you fit a low pressure pump near the fuel tank, an Eddy 500 and if possible an insulation spacer between the carb and the manifold then your problems (at least carb related ones) will be solved.

Whilst on the hunt for a 500 carb try to get a set of 67-55 rods, they will work well as long as the rest of the 500 carb is setup with standard jets.

HTH,

Pete

mylesdw
06-01-10, 07:47 PM
I moved the pump out of the boot and put it behind a lid directly aft of the diff. There is plenty of room there and the pump is both ventilated and well protected. An added bonus is that it is now much easier to fill the diff oil too!