Fuel line questions

[ttraut@unlockit]

Okay, I'm starting to plan my spring projects. My next step (I think -- and will defer to your expert opinions) is to work on the fuel delivery system and I need your help.

I have a 69 RR with a 383 4-speed, headers, electronic ignition, MSD box and coil, performer intake. I bought a 750Mighty Demon (from you know who!), Fram HPG fuel filter, and Carter fuel pump. My thinking is that I'll allow all the fuel that the engine wants/needs. Later modifications this summer will be a new cam and lifters.

My goal is to get this car to 100mph in the quarter mile.

My questions deal with the fuel delivery system:

1) Is this approach (working on the fuel delivery system next) the right approach?

2) Are my existing fuel lines sufficient for my purposes? Do I need to go with larger lines? If so, do I need to use a different size line from my gas tank?

3) If you think I need to get new lines, what's the best approach (or who's the best company)?

4) Where should I connect my Fram HPG fuel filter? I was thinking of attaching it to the body above the axle. What's the best way to plumb this?

5) What questions SHOULD I have asked?

As you can see, I'm new to the fuel line business. I don' know how much is enough (or where to begin).

Any guidance would be appreciated.

Thanks,

Terry

[amxauto-x]

What is the compression ratio? What is the specs on the cam you plan on putting in? At a min would be a 3/8" fuel line. Max would be 1/2 ". What rpm's do you plan on running it at,, at the end of the quarter?

Some people put the filter on the inner fender, or firewall, some will put it back by the tank. Take your pick. Mine is on the inner fender and no problems with it. It is a cannister racing type.

[ehostler]

Talk to the man that you got the carb from...

You'll need to go 3/8 from the sending unit all of the way up. Depending on the HP level of the engine, you may need to upgrade that fuel filter as well.

[skankweirdall]

I'm sure cuda will help you out here, but until then I would recommend the following. If you are going to use a single pump (I'm assuming that is an electric pump) you should run a 1/2" line from tank to pump to filter and the two 3/8" lines to the carb. I would suggest however running two 3/8" lines and two pumps. You can combine them to a single 1/2" line to the filter if you want and then split it again to two 3/8" at the carb. Is that the big can filter? If so it should be under pressure to operate properly.

Yes you need to work on the fuel system, what you want is volume, and working here now will prepare your car for more performance improvements in the future.

Ideally you would want the pump(s) to be gravity fed (lower than the tank) and preferably positioned in such a way as to feed the pump(s) when the car launches. Remember electric pumps push awhole lot better than they suck. If this isn't possible try to mount them as close to the fuel tank and as low as possible. I've seen this work on hundreds of cars, some really fast ones too.

Alternatively one of the larger BG pumps could be used singularly.

[JoeGrapes]

You know what? If all you want to do is go 100mph in the quarter the stock fuel system is fine. I'm not telling you not upgrade the stock fuel system but if money is tight and you have to choose, go for something else you really want. With a slighty modified 440 running 5/16 fuel line and stock pump (was a 383 car) I'm hitting 105-106 in the quarter with no hint of a fuel problem. I also had a '70 383 RR that would hit 100 with only headers and a intake manifold.

[skankweirdall]

The problem there is just because it runs those numbers doesn't mean it doesn't have a problem. You really need a gauge to see what kinda pressure is left on the top end. Putting together a decent fuel system now prepares the car for future performance enhancements, and there will be future enhancements, don't kid yourself.

IMHO this is right up there with chassis improvements. Both of these things should be done before the engine mods start. Just my $.02 but you'll be better off in the long run to spend a little more now than redo everything later.

[JoeGrapes]

You are so right. I don't disagree with anything you say. My point was that since his fuel system is fine for his goal that he should spend the money on something that will give him performance he feel. A cam or gears would be a better next step I think.

[JoeGrapes]

Oh by the way, since I had the car apart this winter I did go with a 3/8 fuel line and a high performance pump. I made no other performance changes so this spring we'll see if I go faster

[skankweirdall]

I understand, it's just that nobody ever gave me that advice when I was building my cars. Nothing is more sobering than saving your hard earned money to by the new fangled whatduzit piece only to find out your car is slower now because it doesn't have enough traction or fuel volume to take advantage of the increased performance offered by your new fangled whatduzit. So now you have to redo something that you already spent your hard earned money on all over again.

[mtrv8n]

You want to hit 100 mph, you have to be geared for 100mph at 5200rpm in 4th gear. We would need to know your tire size and rear gear ratio to know what change needs to be made.

You have a heavy car, so you will need pretty steep gear assuming you are still getting the 335 HP advertised for the 383.
We may reccomend a tire change along with the gears, because with that weight 8 inch tires may not cut the mustard..

When thats all done, you may not like what it feels like on the highway, buzzing along at 3000rpm....

No matter what other mods you make, 100mph at HP peak is what you need to look at. Take her out on the road, 4th gear, and note your rpm at 50mph(assuming your spedo is accurate, maybe have a buddy in a new car pace you. ) if it's less than 2600, you're gonna have to change you gears or tires, or both.

If its higher, then we'll look at why you're not gettin up there..

[skankweirdall]

You can certainly get there without gears, but the ET will suffer. What mtrv8n is saying though is correct if you want to maximise your combo for 100 MPH in the quarter. I don't see the point in doing that to street car though. You can still get there with more streetable gears.

[mtrv8n]

It's gotta be the cheapest way to get there, though..

[skankweirdall]

Probably so, as long as the engine is up to snuff. The trade off in street manners though would be pretty severe in my opinion. If it's only a race car, great. Yes it should be done that way.

[JoeGrapes]

You got that right skank, I wish I had a nickel for every dime I spent on my car and was ethier not happy or wish I had done it that way in the first place. We've all been there I guess

[cuda66273]

Hey Terry

Lot's of good tips here...I think I know your car pretty good and if I remember right you already have a 3/8ths fuel line, Carter mechanical 120 GPH pump and a HPG 1 fuel filter, if this is all correct then I think you'll have enough fuel to get you to 100 MPH.

But your right on that fine edge of fuel starvation at the launch, the big N/Seat and large float bowls of your Demon will help allot, keep an eye on your plugs for detonation and piston material transfer....did we do your distributor? I can't remember it was awhile back now...

Make a pass and see where your at, record your RPM at the stripe and reposrt back to HQ's, we'll give you another 100 opinions on how to make it sneak through the 100 MPH barrier.

Wix makes a replacement filter for your HPG 1, I tested one the other day...

Fram filter: 39 seconds to fill a 1 gallon container

Wix Filter: 32 seconds....about 20% better flow

Why do I spend $10.00 and 2 hours to figure this stuff out??...It may be a question on Final Jeopardy one day and I want to know the answer....LOL

[ttraut@unlockit]

Thanks guys. Let me respond and you can tell me more:

First, this car is primarily street, secondarily highway, and third strip. I'm planning on buying 3.91 gears this summer (currently it's a 3.23 one-legger). I have 26" tires and know that this car will not be a highway cruiser with the 3.91 gears; that's fine given my purpose.

Second, so far I have nothing to fear about traction. I can barely light up even the one wheel from a standing start. Part of it is that the tires are pretty wide (255/60TR15), and some of it may be drivetrain/gears (see question #3 below), but most of it I'm guessing is engine performance.

Third, what you're seeing is me in the beginning stages of my engine build-up. I'm bolting on things rather than rebuilding the engine. Bolt-ons so far have been performer manifold, electronic ignition (recurved distributor by Mr. Gould), MSD ECU and coil, new wires. It had headers so I figured the next step would be to replace the carb; Don suggested the Mighty Demon 750 (if, for nothing else, to give the rest of the engine something to strive for), Carter pump, and Fram HPG filter.

My questions about the fuel line came about as the result of 1) a loonnnggg winter, and 2) thinking about all these fuel delivery system enhancements bolted onto a stock piping system.

1) I don't know what stock size tubing is but it sure looks like a 5/16" connector in the rear. What is stock on a 69RR 383? And is it enough to feed a 750 Mighty Demon? If not, I'd rather replace the whole thing at once and avoid JoeGrape's issue of not building it right the first time. Since a) I'm not too mechanically inclined (but working on it ), and b) pretty slow, I want to get all the stuff I need and spend an afternoon putting it all together.

2) I don't know the cam that I'm looking to put in it. I'm leaning towards a custom grind from Don since he does know my car. I figure that the cam selection (and whatever else comes with it) will come after the 3.91 gears.

3) I have a question about my clutch which may be affecting my launch. When I pop the clutch with RPMs at about 4000, I think I should feel some immediate grab or tire burn. I don't. It feels more like an automatic -- drivetrain trying to catch up with the engine revs. Might I need to make adjustments to the clutch? Any tips for doing that?

For those of you who would like to see what I started with and what I've got, check out http://users.adelphia.net/~trtraut/index.html. I think you'll like the picture of me getting my *SS waxed by a Plymouth Voyager !!!

Terry

[cuda66273]

Excellent story!

But...what the hell are you doing up so early? I have an excuse...I'm old and don't sleep much anymore....few hours here and there...

By the way if you guy's call and Mrs. Cuda she says I'm sleeping...better let the bear sleep.....I don't do it often but when I do it's best not to wake me up....LOL