stalling under heavy breaking

[martinlaw]

What is the mod. that can be made to a 750 double pumper to prevent the car stalling under heavy breaking?

Cheers,
Martin.

[TuxMan]

E.F.I sorry Martin !!! check float levels , is the carb level if not fit a 5degree wedge plate ,on scuffs i found resetting all the idle jets then tweaking to get the best tickover helps ,you can get some sponge infills for the float chambers as well which should help the fuel slosh !!

[GTRCLIVE]

LSX..... or left foot brake like the rest of us had to....

[gtr-gaz]

GTRCLIVE said:

... or left foot brake like the rest of us had to....

I tried that once. Never again, it nearly ended in disaster!

[bluesatin]

use the hp carb!

[Paul.B]

gtr-gaz said:

GTRCLIVE said:

... or left foot brake like the rest of us had to....

I tried that once. Never again, it nearly ended in disaster!

Find yourself hanging off the 4-points? There is a certain technique and you need a lot of practice.


I found heel & toe changes helped but never totaly eliminated the problem.


Paul.B

[gtr-gaz]

Paul.B said:

gtr-gaz said:

GTRCLIVE said:

... or left foot brake like the rest of us had to....

I tried that once. Never again, it nearly ended in disaster!

Find yourself hanging off the 4-points?

You guessed it!

[LuckyP]

Frustrating isn't it.

Ask the factory what they'd suggest. Id say that is a saftey issue, I've stalled on roundabouts more than once - and that ain't good. A manufacturer wouldn't be able to sell a car that did this!!!

Richard?

Lucky

[kylemrushall]

LuckyP said:

Frustrating isn't it.

Ask the factory what they'd suggest. Id say that is a saftey issue, I've stalled on roundabouts more than once - and that ain't good. A manufacturer wouldn't be able to sell a car that did this!!!

Richard?

Lucky

it wont be efi!!

i didnt have a problem with this Martin

[Boosted LS1]

If it's stalling then it's clearly not set up properly. Could be fuel slosh in which case main jet extensions may help or as Simon says a base plate to level the carb may be the solution. Maybe set the fuel level higher for the primary's. Adjusting the idle circuits may work as might ensuring the throttle blades are closed enough to see the transition slots. I'm not sure if the stalling is a sudden loss of fuel or air but my guess is that you have the blades open so the fault would be loss of fuel.

[fastco]

martinlaw said:

What is the mod. that can be made to a 750 double pumper to prevent the car stalling under heavy breaking?

Cheers,
Martin.

Hello Martin... install float bowl extensions...and Holley slosh control kit & (secondary jet extensions with notched Nitro float as Boosted recommended)...set fuel pressure @ 7 psi...
1 more thing take rubber hose 5/16 ID fit over primary & secondary bowl vent tubes... arc to clear air horn cut to length.. now with razor cut middle of rubber tube in 1/2 for along prox 2 inches..load rubber hose to vent tubes face slit up towards air cleaner lid.
This will vent bowls and stop fuel from slosh'n out'a tubes during hard excelloration or hard braking. / Old school trick!


On secondary extensions increase jet size by 2 #'s

Cheers! Dr,Dee
PS: Fee this lesson 1 pie 1 large chips 1 pint local brew ..after Stoneleigh show 08..... ha

[eliot]

fastco said:

1 more thing take rubber hose 5/16 ID fit over primary & secondary bowl vent tubes... arc to clear air horn cut to length.. now with razor cut middle of rubber tube in 1/2 for along prox 2 inches..load rubber hose to vent tubes face slit up towards air cleaner lid.
This will vent bowls and stop fuel from slosh'n out'a tubes during hard excelloration or hard braking. / Old school trick!

That sounds a good idea.

[Crazy of Cookham]

As Blue said HP Carb. Couple of weeks fettling with carb floats and now will not stall. Also does not choke out going around corners.

[martinlaw]

Thanks everyone for all the advise.

I will look into the suggestions and find someone who knows what they are doing with carb as I have not got a clue.

Cheers,
Martin.

[ultimaCZ]

Boosted LS1 said:

If it's stalling then it's clearly not set up properly. Could be fuel slosh in which case main jet extensions may help or as Simon says a base plate to level the carb may be the solution. Maybe set the fuel level higher for the primary's. Adjusting the idle circuits may work as might ensuring the throttle blades are closed enough to see the transition slots. I'm not sure if the stalling is a sudden loss of fuel or air but my guess is that you have the blades open so the fault would be loss of fuel.

The carb gets flooded, that is sure. The HP carb and other adjustments help to some extent, but still the idle will drop under heavy breaking, sometimes it will also stall. Especially if A/C is switched on, which is a further problem for the idle speed. And even if it does not stall, then you get a lot of unburnt fuel into the engine, which is not good either. Had it all, tried it all. Only way to go is EFI, or you just live with it. But dont believe anybody who tells you that a carb set-up will sort it completely

[kylemrushall]

martin ....

put the carb on the sport, put your efi from the sport on the GTR??

I love it when a plan comes together.

[Boosted LS1]

ultimaCZ said:

Boosted LS1 said:

If it's stalling then it's clearly not set up properly. Could be fuel slosh in which case main jet extensions may help or as Simon says a base plate to level the carb may be the solution. Maybe set the fuel level higher for the primary's. Adjusting the idle circuits may work as might ensuring the throttle blades are closed enough to see the transition slots. I'm not sure if the stalling is a sudden loss of fuel or air but my guess is that you have the blades open so the fault would be loss of fuel.

The carb gets flooded, that is sure. The HP carb and other adjustments help to some extent, but still the idle will drop under heavy breaking, sometimes it will also stall. Especially if A/C is switched on, which is a further problem for the idle speed. And even if it does not stall, then you get a lot of unburnt fuel into the engine, which is not good either. Had it all, tried it all. Only way to go is EFI, or you just live with it. But dont believe anybody who tells you that a carb set-up will sort it completely

Not having your car I can't say what's going on but it will be in the settings. You should be able to get close with a properly set up holley. It needs air and fuel progressivly so even if you snap the blades closed the circuits should work in reverse ie the opposite to accellerating. It's hard to compensate for the air-con as you would need to have a higher base idle setting (basically a pain with the aircon off), blades open a tad more but not past the transition slots. If you needed more air you would drill the blades just to keep the transition slots active. Otherwise you would have a big flow problem between the idle and main circuits. I enjoyed the simplicity of my holleys but can see the drawbacks. The opposite scenario is efi thet's just to complicated for ordinary engines/use.

Boosted.