Drag race fuel system

[dragrcr50]

not to butt in but i went to the track tonight with the nova for the first time and all week i have been fighting my car at wide open trhrottle.  I too have a holley blue with regulator at mtr and each line feeds a 660 center squirter carb.  at wot it just lays down waaaaah, ease up just a tad and it runs. it will not run at wot in the shop or the track no change.  i too have msd distr and coil and 6 al with all the right stuff. it is a 377 alum head 14.8 compr lunati roller 276/284 at 50 645/650 on a 102 cl.  mad 688 hp on a dyno with a single intake and a 850 carb @6200 rpm. this will shift a 7600 .  however it will not run at wot.  timing at 39 degrees and the pump will pump 1 gallon in 12 seconds ... any ideas.  I feel your pain crosley, should have kept the willys haha..........

[chimp koose]

Dragrcr50 .When you say that the motor picks back up when you back off the throttle it brings one thing to mind. Your float bowls are running low. When you back off at high rpm ,the throttles shutting partially will increase the vacuum signal at the boosters enabling a higher draw from the booster venturis,allowing it to draw fuel from lower down in the float bowl thus giving it the fuel it needs momentarily.A holley blue pump puts out 110 gal/hr at free flow,I dont think that is enough pump for your combo.Please do not be offended but I Also think you are running too much spark lead.A 377 uses a 4.125" based bore which is more detonation prone than the same CR in a 4.000 based bore engine.At 14.8:1 in a 2400-2600LB  car ,39degrees sounds a bit high.A racer friend of mine years ago was telling us how his 327 liked big jets . He was jetting a single 780holley up into the 90's and picking up more et. Then he told us how much spark lead he was running and the jetting made sense. He had WAY too much advance in the timing and was curing a detonation problem with a very rich,slow to burn fuel mixture,causing an increase in performance.I know it is far easier to play armchair quarterback with a tuneup than to tough it out at the track ,please do not be offended by my suggestions.Let us know what you find.

[C9]

Crosley; is your pal your pal running one of these tanks?


(Not shown is the sheet aluminum firewall between seat and trunk.)

Summit lists them as a fuel cell in their catalog, but they're not.
They are an un-baffled gas tank.

Even so, the pickup's pretty close to the bottom and is a non-flex steel (?) line.
I could see it not picking up due to accelleration forces rolling one gallon or so up the back wall, but if it has 3-4 gallons in it there should be no problem.

If this tank is in use there's a good chance there's weeping around the filler/tank juncture due to the way the bolt ring is built.

I wrote a detailed article on this and I'll try to post it here in a bit.

One other thing the article covers is the need for bracing the top.
The four mounting feet will flex back and forth and rip the tank material proper.

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Chimp - good points on the timing.

Fwiw, my 462"Buick 9.0/1 CR runs 32* all-in.

I note as well some of the fast Buick runners run as low as 28* all-in with their 9-10 second Camaro size and larger cars.

Probably one reason I'm getting away with being two stages lean - as per the Edelbrock manual - with the 750 cfm in the roadster.
Only other mod was swapping metering rod springs to match engine vacuum.

Leaned out for the 3300' altitude I now live at, but the car runs great as high as 6500' and down at the river where it's 500'.

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One further thought for Crosley.

If you gutted one of the nice looking aluminum A/C dryers and TIG'd it or used JB Weld to get it back together you'd have a nice little reservoir.

Plumb it into the fuel system so it can gravity flow to the carbs.

Would be interesting to see if the additional fuel would carry you over the length of the track or at least a little farther.

That would definitely indicate low fuel pressure.

Did I mention a fuel pressure gauge?

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A small fwiw and off tangent a bit.

Perhaps some question my use of a #6 vent line with #8 feed.
It works well for me and probably would for most moderate HP cars.

On my TT-500 500cc four stroke dirt bike, if you fell over - and if you don't fall once in a while you're not going fast enough - and the bike had the tires a little higher than the tank, it would siphon fuel out of the about 1/4" vent line.
Said vent line going from cap to the front down tube.

If you didn't get up right away a lot of fuel could be lost.

The problem resolved for the most part by sticking a main jet in the vent line that was a little bigger then the carb's main jet.

Never had a fuel starvation problem with this setup and that includes some long 80-90 mph runs up a long and sandy riverbed near Jawbone Canyon.
Scared hell out of folks on the highway who were running 65-75 mph when we'd come out from under the bridge across the river and pulled away from them.

Plug checks showed the engine was not runnng lean during these long runs.
As well as on longer runs down the many miles of smooth aqueduct dirt roads.

If you didn't have a good top end, the gang would run away from you and you'd be half blind and eating dust....

[dragrcr50]

Dragrcr50 .When you say that the motor picks back up when you back off the throttle it brings one thing to mind. Your float bowls are running low. When you back off at high rpm ,the throttles shutting partially will increase the vacuum signal at the boosters enabling a higher draw from the booster venturis,allowing it to draw fuel from lower down in the float bowl thus giving it the fuel it needs momentarily.A holley blue pump puts out 110 gal/hr at free flow,I dont think that is enough pump for your combo.Please do not be offended but I Also think you are running too much spark lead.A 377 uses a 4.125" based bore which is more detonation prone than the same CR in a 4.000 based bore engine.At 14.8:1 in a 2400-2600LB  car ,39degrees sounds a bit high.A racer friend of mine years ago was telling us how his 327 liked big jets . He was jetting a single 780holley up into the 90's and picking up more et. Then he told us how much spark lead he was running and the jetting made sense. He had WAY too much advance in the timing and was curing a detonation problem with a very rich,slow to burn fuel mixture,causing an increase in performance.I know it is far easier to play armchair quarterback with a tuneup than to tough it out at the track ,please do not be offended by my suggestions.Let us know what you find.

I appreciate your thoughts,  let me say this condition is the same in the shop hot or cold or on the track if i raise the floats any at all it will overflow the vents and ive had from 6 to 9 lbs pressure. no change.  i really havent tried a little less timing, once i backed it up a tad and it blew back through the carbs.  when i whacked it. i ran the same cam in a 383 that had the same compression and heads etc and always did 39 degrees in it so i assumed it was a good place to start.  also the pump will fill one callon in 12 seconds?  and i can kill the eng with one hit at wod in the shop free rev.   I dont want to for the simple reason it is a nostalgia car but i may have to put a single 850 carb on it, i feel i should be able to make it work.  ...thoughts now...

[dragrcr50]

crosley,  i had a buddy that does super stock mtrs look at my carb situation and he found two needle and seats in these carbs that were .060 long which were keeping the bowls very low  or out of gas,   if you set the tops at the max up where the lock would still work on it the seat was mostly closed.  so we jetted it bgack up to the holley spec 76 jets  which is .084 .  it should run for sure now....  thanks for all the input guys   sam

[chimp koose]

Good to hear you found the problem.

[Crosley.In.AZ]

crosley,  i had a buddy that does super stock mtrs look at my carb situation and he found two needle and seats in these carbs that were .060 long which were keeping the bowls very low  or out of gas,   if you set the tops at the max up where the lock would still work on it the seat was mostly closed.  so we jetted it bgack up to the holley spec 76 jets  which is .084 .  it should run for sure now....  thanks for all the input guys   sam

Sam,

there have been 2 sets of carbs on the engine with the same mis fire.

Tuesday my buddy finished the fuel system re-plumb....  so naturally he tested everything again.  This  time there was only 8 psi  dead head test on the Holley pump... previous test show'd  14 psi in a dead head test.

So , he is replacing the pump  today

[dragrcr50]

crosley, guys,  I got mine running tonight and with everything the same just bolted the carbs back on it has a very slight hesitation at wot off idle.  but rpms great not dead dont die looking good. Also i went back and added  timing to 41 degrees and it has no hesitation at all. not rich no smoke and no black soot etc. the mtr likes it i cant wait now to run it , however we are forcast 6 inches of snow fri so races sat might be preempted...............  love them race cars.   hope the J gets straightend out so he can run my old willys some out there ...........sam

[Crosley.In.AZ]

crosley, guys,  I got mine running tonight and with everything the same just bolted the carbs back on it has a very slight hesitation at wot off idle.  but rpms great not dead dont die looking good. Also i went back and added  timing to 41 degrees and it has no hesitation at all. not rich no smoke and no black soot etc. the mtr likes it i cant wait now to run it , however we are forcast 6 inches of snow fri so races sat might be preempted...............  love them race cars.   hope the J gets straightend out so he can run my old willys some out there ...........sam

Sam,

The  big block that was in the Aero Willys is now in the White Henry J that Chuck owns.  The Aero Willys has a 572 motor in it ,  if you did not know that.

Bert may test n tune his orange Henry J  on friday evening to see if the fuel system changes helps his car.

[dragrcr50]

well tell chuck that if he would put a smaller camshaft with a 110 centerline that car will pick up about a half second it has a real big blower camshaft in it.

[Anonymous]

500" DRCE engine with Olds billet heads, aluminum block, 6800 rpm chip at launch, 9000 rpm chip on the top end, Lenco trans.

8.13 @ 166 mph.

Rocket Racing has symmetrical port intake and heads like those... they're great!

[Glen]

Tony, here is a pic of your buddies car.  I found it on Craig Pike's website "my ride is me"

http://www.myrideisme.com/FullEventImage/d2c485ad07bc969d6d94549cab0feae6/

[Crosley.In.AZ]

Hi Glen,

yes , I've seen the photos.  Craig is nice fellow.

The Henry J photographs well and is on the Drag strip  flier for the next Nostalgia event in April.  Too bad it will not make a full power pass yet.