BosMobile

Hey guys,i have a working well,but stock ,fuel system.I like to dragrace and wonder if my stock fuel system may be holding my car back.I installed a fuel gauge,it reads 7psi.The car leaves hard ,then seems to die after 60'.Someone suggested fuel pressure might be why.Everything is stock,except the 750DP holley.I'ts a moderatly built 461,400,.3.73 posi.72 cutlass.Adj. lower arms,10.5 slick,adj. shocks.I only have access to 1/8 mile track.Best time,1.62 60',8.11,at 83 mph.Any suggestions on what i may need to do to go faster ,or do i need to look eleswhere?Sorry,no 330' timer.Will provide more info if needed,thanks for any advice,suggestions,later,BO

Rickman48

I've used the Holley mechanical pump without starvation, but you might consider resetting your floats as high as possible, first.
There's also the 'high-flow' needle and seat, deflectors to prevent uncovering the jets during acceleration, and a 50 CC accelerator pump, if you've gone to larger squirters!
Might try shifting a little earlier on the 1-2 shift, too!

joe_padavano

You've got a fuel pressure gauge - what is it doing when the car noses over?

BosMobile

Thanks for replys,I'd rather stick with a mechanical pump,just to keep things simple,IE less to tear up.I dont mind buying a high flow or bigger volume pump{like the holley mech} My fuel gauge seems to remain steady close to 7psi.My carb is a holley 4010 ,750dp with mechanical secondaries.the gauge is a temporary set-up,just to see where the preassure was{must admit its kind of"micky mouse"}

TripDeuces

It may be too much fuel rather than to little. Is fuel coming out of the front bowl and puking into the primary side of the carb? On hard acceleration fuel sloshes to the back of the bowl and will climb right out the vent. Might think about getting vent tubes for that Holley.
Are you running an air cleaner assembly? Without air being forced directly into the carb throat I've seen fuel being sucked right out of the bowl due to air flow over the TOP of the carb. I doubt this happens in 60' but given enough air flow it will happen every time.
Pressure and volume are two very different things. You can have 7 pounds all day but if the volume of fuel drops it will do the same thing. What size fuel line is from the tank to the pump? I'd go with a minimum of 3/8. Is the sock in the tank plugged up or collapsed?
So many things to consider here. Basically a 12 second car in the 1/4 miles needs to fill a one gallon gas can in 35 seconds.

Here a good article from Barry Grant: http://www.barrygrant.com/bgfuel/default.aspx?page=81

joe_padavano

If the fuel pressure remains steady during the run, why do you think the pump is the problem?

BosMobile

Thanks for your help,I'm baseing my "investigation" on what my car runs in 60' .Guys with similar times are running in the 7's.Thats only 1/10th away from my goal with this combo.Then i want to fix the paint,interior,you know.the "pretty stuff".Chrome dont get you home,but its not hard to look at.Tripleduece,I have the floats set where fuel just runs out the plugs,I think the rear ones a little high,because if you really get on the brakes it will die.Cranks right back up,but ive been meaning to lower it slighty.The whole fuel system is stock,except for the mentioned carb.I love to tinker on this car,so its not broken,I just want a little more speed.7's are respectable time for a car that idle all day in AL heat.Thanks for trying to help me .Youve already given me some ideas to try,thanks again,later,BO

TripDeuces

It's been a long time but if I remember right I used to run a 1.64 and ran high 7s in the 1/8th. Btw, having the floats set correctly has nothing to do with pulling fuel from the bowl due to other problems. I've coated my windshield with fuel before when not running an air cleaner or at least something directing it into the carb throat. Air rushing over the inlet will act just like a siphon at speed. To this day I always use an air cleaner with a K&N filter and never had a problem.
On a side topic tomorrow I'm dropping my tank to seal and coat it inside. I have a bad miss and kind of a fluttering problem going on right now. I blew air through the line from front to back and the problem was solved but now it's back so I know either the sock is plugged or something else is. This is with 6.5# the whole way. As I said, pressure and volume are two separate issues. You have one solved now you need to look at volume. Good luck

442_Mustang

u can extend the carb vents with a couple short hunks of vacuum hose just to see if it helps.

BosMobile

Thanks for the killer artical, it really helped me understand how the fuel system works.I'm prety sure now, that i have a volume problem.The gas can test will tell me for sure. I'f i put a 1/2" fuel line from the tank to the mecanical pump,will that increase the volume? Will i have to change the pick-up tube as well? If so,I'm getting close to the cost of a fuel cell.i'd like to set up a 5gal cell{for race gas} and keep my stock tank for street use{reg}.Surly someone has tiried this before.Seems a switch/valve would work for this .I don't run my air cleaner at the track,but the one i have is a K&N.I'll make a vent tube as well.I have a hard time of remebering all your questions.So i may need to post xtra replys to get it right.Thanks again ,later,BO

BosMobile

Hey TRIP,my car 60s in 1.62.Thats what i mean ,car should run 7s.

TripDeuces

I have to strongly suggest you run an air cleaner with your set up. Unless you have a forced air set up on it and are directing air directly into the air horn. Any air flowing perpendicular to the air horn will tend to pull on the bowl causing the vent to puke.

Anything you do to help fuel get to the carb will help, bigger line etc. You don't need a fuel cell but you can get 1/2 pick ups from RobbMc. Just keep in mind that mechanical fuel pumps are poor at pulling fuel but great at pushing it. Bigger lines mean more weight (in fuel) which puts a bigger strain on the mechanical pump sucking it forward. It's marginal as far as weight goes but it does exacerbate the problem. I'd think about a pusher electric pump if you're really serious. Even small cheap ones will help. I had a buddy with a 67 GTO and all he did was add one of those cheap Carter pumps with the 5/16 inlet and outlet (the horror) and it made a huge difference in performance. I'm talking a tenth of a second easy. As far as your vent tube you may have a vented cap already, it should state it on the cap. If not you'll definitely need a vent. I'm not a fan of vented caps because fuel will slosh to the back of the tank making a vented cap useless. Vents need to be up front on the tank like 66-67s are.

Funny thing about my 7 second run. The car was running strong that night too, who knows why. I was running a slower car and was catching him easy, too easy. I'm thinking to myself why doesn't this seem right. Then I saw his brake lights and I knew he was sand bagging me. So I jump on the brakes knowing I'm going to break out. I slide through the lights with four tires belching smoke and hanging on for dear life. I ran an 8.08 in full panic mode. We're looking at each other on the return road wondering who won because it was that close. Turns out we both broke out but he did by less and beat me by .003 of a second. Talk about being pissed off. Consistency is key, try to strive for it.

BosMobile

Thanks again,I'm convinced there is some performance to be gained here.I'll start running the air cleaner,and order a elec pump and 1/2" line.I can start there.I,ll hollar back when i get that done,we'll see.later,BO

TripDeuces

Took my tank down yesterday to seal it. Found the tank to be spotless but I went ahead with the sealing anyway and will finish it tomorrow. On a side note the Eastwood kit is excellent albeit time consuming. I did find the sock crushed and ripped open. I thought this might be a reason for the restriction I was having so I fixed that. Since I knew I had a clog of some kind I started working on the line from front to tank also. When I put the cleaner down the line nothing happened at first. Finally saw some bubbles forming so I knew action was in process and then it gave way and this goo came out of the line. Almost looked like tar. I have no idea what it is but it's clean now. Can't wait to get it all back together and see how it works now. Good Luck with your project.

George

BosMobile

Sounds like you'll be picking up some performance as well.I went to robbmc ,1/2" fuel pick up is 150 bucks ,i thought it would be much higher.I have a few directions i can go,so i'm wieghing it out.later,BO

BosMobile

Hey Tripleduece,I've been thinking it over,about my fuel system.I'd like to run a duel system.Anyone ever combined a stock fuel system with an elec. pump.I've been searcing a little on the subject,havent come up with anything i'd consider reliable yet.My idea{its not a new one i know}is to combine a 5gal. fuelcell with my factory tank.The cell would hold race fuel ,while the factory tank would run regular gas.The part i'm trying to figure out is how to combine the two lines.I'm thinking a "y block" so i can use the 1/2" alum line from the tanks to the first filter ,then on to the elec. pump.I'll plumb the system to the frt. from there{with 1/2" stuff to reg. and carb} Any suggestions on how i could combine the two fuel lines without causing any restrictions?Also a way to switch between the two tanks,I know i could simply use two shut-off valves,but it would be better if i could find an elec.type switch,like the older GM trucks with dual tanks. What do you think?I't would be cool to me.My car will burn reg.I've got those world reknown"10.5 compresion 2323 forged pistons".Which means simply its more like 9/1 compresion.But i would at the very least run 93 octane in the 5gal cell.I've got another 455 with nearly all the parts to buidl a "big boy",So this set up will come in handy later,when i'll need race gas.Any thoughts or advise would be much appciated,later,BO

TripDeuces

Since you run at a sanctioned track (NHRA?) I'm not sure what the rule book says about what you're proposing. I'd check that out first. I do like your idea. I'm not aware of any electric solenoids for switching fuel but I'm sure someone does. I'd shy away from the GM truck one only because I think it will be too small a diameter for your needs.

BosMobile

Hey trip2,thanks for helping so much.Thats what this site is all about.I havent had a computer for a while ,i apoloize.There 's always someone that will help you.So thanks everyone.My trade is auto painting,so i like to answer those qustions,just suggestions really. I bite the bullet today,I called summit and ordered 1/2" fuel system,from tank to regulator,now i've got to order a fuel cell,and a set-up for the dual feed carb .I't s all 1/2 "so, i shound'nt ever have to worry about my fuel volume or pressure again."Knock on wood" as we say here in the south.I don't know how to start a new paragraph,maybe you can help me with that too.Anyhow ,santioned track,hardly.They don't even have a 330' timer.RULESon't **** off the regulars,or the track guys.Thats meant to be funny ,but its close to the truth.Theres other tracks around{no 1/4 miles},but nothing close,I can run on fridays for free untill i get the car consistent.Thanks again,for all your advise,glad to have someone to bounce my ideas off of.Anyhow,hows your gas tank coming,i've sealed a motor cycle tank before.was'nt to bad.Well lets all rejoice!Hot rods are great,beer is good,and people are crazy,later,BO

TripDeuces

Gas tank is in. Just waiting for it to dry which should be Wednesday. I'll fire it up and see how it worked.

BosMobile

Yeah,that's cool.You'll probaly be shocked by how much power your car makes now that you cleaned those fuel lines.By the way, what kind of car do you have?Mines a 72'cutlass S,factory big block.Owned mine for about 20 years. First real car i had.{i was'nt kidding about the paragraph thing}I couldve had a similar situation,but i don't want to know now!Parts on the way ,so might as well install & see.Still haven't ruled out "dual fuel tanks".Waiting on my parts,later,BO

TripDeuces

This is my 66 Cutlass. Just a 330 SBO for now but the L69 BBO will go in soon I hope. My drag car was a 70 Cutlass S. Initially it was my daily driver but I went all drag and eventually sold it to two people. One wanted the frame and the other took everything else. Although I like drag racing I doubt I'll ever have another purpose built drag car. I like the street scene too much along with the car shows.

BosMobile

That's cool,I want mine to stay "streetable"I havent driven it much in the last few years.I just gave my 83, olds {no paint work ever}driver to my 16 yr. son.He's a prety responsible kid so maybe he won,t wad it up.I'ts funny really,to want your kids to be safe drivers ,knowing i drove like a bat outta hell.Anyhow I just put a posi w/3.42's in there for him ,and said, your buying the tires.Fair enough.I'm kind of doing my"bucket list"I became disabled about 5yrs ago,sadly it afects my throtle foot.So at sometime i might have hand controls.Does'nt matter I,ll always love cars.I,m not much for "showing"don't have good paint.{im a painter ,what a shock!}But ill love driving to shows,the kids big enough to push me around now,HA.Later on,BO

TripDeuces

Just had it out for a cruise and it's working great. Definitely a difference in the midrange and top end. She's no screamer but it does go decent for a SBO. I'm sure the 4.10s have something to do with that. They will have to come out at some point I think for something a little tamer. Take care

BosMobile

Yeah, A succesful project always is rewarding.Only a car guy can understand that .Glad you got her back on the road.You would'nt happen to know anything abuot these --AN fittings would you?I got my 1/2" fuel lines now,just looking for some suggestions on exactually what i need to do.I'm already aware of the 37* degree flares,which I'm not threa'ld about.I'ts ok i need it,but any suggestions would be appriciated.Talk to you later,BO

TripDeuces

I know some about them. Is there a particular question? I'm assuming you got the RobbMc sender with AN fittings installed? If that's the case you have an AN8 fitting on it which would be half inch in size (inside diameter). Each number is equal to a 1/16 inch. So 8 x 1/16 = 1/2 inch. Yes it is 37* so if you're going to hard line it you'll need a 37* flare tool I'm in the middle of plumbing my Tri-Carb setup with hard line and AN fittings. I'm no expert but I'm learning a lot. I consider that part of the fun.
My only question is what does ethanol do to aluminum or copper fuel line? If anyone knows I'd be interested to hear.

507OLDS

If you are going to upgrade your fuel lines to 1/2",then all of them need to follow.If you do the main lines,and the sending unit,then you need a pump that will coincide,and the Holley is not one of them.The RobbMc pump is the only mechanical pump available to the public right now,that suits the need.The pump I am working with as not been tested enough to turn it loose.
On another note,Mark Prince runs the RobbMc pump,with stock lines & stock sending unit,and has ran his 72 W30 into the 11's.very impressive car.
Another thing to consider is the fuel level in the tank.When you leave the line,all the fuel moves to the rear of the tank,away from the sending unit,and can starve the system,if there is not enough fuel in the tank.

BlackGold

In the interest of keeping things as stock as possible, but still delivering enough fuel, does anyone here know of a suitable in-tank pump that we could use to feed the mechanical pump up front? Obviously it would have to be a low-pressure pump, not one intended for fuel injection.

I seem to recall someone posting (on another board) several years ago about how they had rigged such a system by adapting a send unit/pump from another application. But I can't find anything on it now.

BosMobile

Hey guys,thanks for helping.My computer crashed,{cant seem to keep one up}Anyhow,don't ever think i would disrespect you by not answering back,or at the very least,thanking you. I bought -8 AN fittings and alum.1/2" line from filter to regulater.I'm a "greenhorn"on this AN stuff.I was under the impresion that tube sleeves would seal these lines.I ordered this stuff to upgrade my fuel system,which was not up to par.I want to do this once,as well as right.I havent got the lines to the carb,or the tank.Anyhow i'll keep it short for now,but i really need some direction on what to do with these fittings and such.I've searched it but did'nt find any good articles.Just a good research site would be great!Thanks,as always .On a side note i'm thrilled 507OLDS that you responded to one of my posts!My car is almost idenical to yours{I don't have a 507}I'd like to build this fuel system so that it would support such an engine .Trick Family,your car is my screen saver!Thanks again,later,BO

TripDeuces

Today I hooked up the switch (momentary line lock switch) for the S/P TH400 and fixed the choke. My buddy came over and of course we had to go for a ride. Even with the extra 400+ pounds in the car (his fat behind and a full tank of gas) she was impressive. Using the S/P she came out of the hole sideways and was just plain screaming through the gears. I have to admit the 4.10s are a bit much for the street but I've never had this 330ci move like this before. It brought back memories. It's more impressive when I you realize it's a heavier convertible doing it. A lot of 'Ricers' are going to get schooled before I'm done, lol.

BosMobile

Hey dude,Whats up,I can relate on the 4.10 gear,thats the biggest difference you can "feel" in a car.I'm no expert.I've only changed the gear in a couple cars ,most recently a swap from a 2.14,to a 3.42 posi. in the car i just gave my son in March{16 yr old}.I drove that car 4 years,sounded awesome,but wouldnt spin a tire.NOW?... We'll ,he needs to get a job at a tire store.I'm a kind of confused by what you desribed in your last post .I'm not real "savy" on some terms folks use ,here on the net. So,I'd hope you don't mind explaining what you meant in your last post. S/P ?? Just a gearhead,later,BO

TripDeuces

Switch Pitch TH400 transmission. Has two stall settings. Mine is 1600 and 3200 rpm (depending on the engine). I doubt the 330 sees 3200 rpm. Traditionally it's operated by the throttle mechanism but I bypassed it by using a momentary switch to activate it. Come out of the hole at high stall for higher torque and quicker acceleration (assuming your tires can handle it) and then switch back to low stall to complete the run. The best of both worlds.

BosMobile

Thanks,I've heard that term before .I feel kind -of dumb asking,although ,thats how i learn.Seems to me that ,this S/P would be desireable,for a racer anyhow.Whats the catch?I's this TH/400 any different in size ,or bolt pattern?An mostly ,does it work good?I,m thinking they made these TH400's in the mid 60's.So clue me in if you'ld like to.Sounds good in theory,especialy in a street/strip car.Sorry so long reply ,powers been off all morning here,later,BO

TripDeuces

It's no different at all in outward appearance. Same size, shape, bolts, etc. Torque converter, front pump and input shaft are different and there is an extra solenoid that activates it on the valve body. Looks just like the kick down solenoid. Also a two prong plug on the side of the case vs one prong.
They were desirable for racing at one time but the changing of the pitch from high to low stall can vary in the time it takes to happen. You're only talking fractions of a second but in drag racing where every tenth is important they just weren't consistent enough. Also the first generation throttle activators kept the trans in high stall as long as the pedal was to the floor which greatly increased the slip. When I raced it back in the 80's I would typically lose a tenth of a second in the 1/8th if I left it on the whole run. For the street it's a blast as it multiplies the torque output greatly. It can also be used to stop creep at stop lights if you have a big cam.

BosMobile

OK,I got it .Thanks for clarifing that for me.So how much a change did you feel with the fuel system change?Just kidding a little,{hoping your friend is'nt on this site too]but ,400 lbs is worth a couple tenths.I'm sorry that was wrong ...some times a little sence of humor ,can go a long way.I'm enjoying talk'in with you,let's keep it going ,later on,BO

TripDeuces

Nice article in the new Popular Hot Rodding Sept '11 about the Switch Pitch. Looks like Phoenix Transmission makes them now.

BosMobile

Hey,Trip2,sorry i hav'nt responded.I've been spending every waking moment trying to get this fuel system figured out.WOW!It took a me a minute.{spelling}Finally have a realistic plan,still working out some of the smaller details.Theres alot more that comes into play than i would've thought.More money too!As with any hot rod project, a well planed system that i won't have to do again ,is money well spent.You know,ounce of prevention,worth a pound of cure .Anyhow ,how'es your hotrod running since the gas tank project?Good ,i hope .I've been learning a ton about fuel systems,it's very interesting.My car could,ve used this a long time ago!If it doesnt get alot faster i'll be surprised.Man ,theres so much information it boggles the mind.{or what i,ve got left}I,f you see mine ,could you please return it?Don,t remember the address.Later,BO I'll check out that mag,on the S/P,interested.