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[alpalwal]

First - some pictures

http://img695.imageshack.us/img695/6404/picture002op.jpg
http://img696.imageshack.us/img696/7346/picture001gd.jpg
http://img510.imageshack.us/img510/8409/picture003z.jpg
http://img510.imageshack.us/img510/5548/picture004ry.jpg

We're almost done turboing my brother's 1967 Mustang. Stock block and carb with a conservative 5lbs of boost on a Holset HX35 turbo.

All the piping is done and basically everything is good to go except the fuel system. I was helping a lot with the turbo part but I'm pretty dumb when it comes to carbs and fuel management.

We have set up an electric fuel pump and a fuel pressure regulator. We will be switching the FPR out for a boost referenced one when we get a chance. Right now the FPR is turned down to ~6 lbs or so.

My question is about carb tuning. On the left side of the carb (3rd picture) there are two adjustment screws (one brass at the bottom, and one silver on the right) I think the brass one is the mixture and the right one is the accelerator pump. Is that right? Also, where should these be set on a stock car and what does turning them each way do?

The 4th picture is the right side of the carb and I just wanted to include it just in case there is another adjustment screw I'm missing.

The car runs ok right now but when we get to about 50mph and we give it any gas the engine falls on it's face like it's running out of fuel. I'm not sure of that's something we can tune out with the adjustment knobs or if we need to switch out the FPR for a boost referenced one.

Just to try it out we upped the fuel pressure to about 8lbs and the car worked better at freeway speeds but it was running way rich at idle and it died a couple of times.



Sorry for the long post. If there is anything else I left out let me know and I'll do my best to describe it better.

[92CXyD]

all but the third picture fail.

[alpalwal]

all but the third picture fail.

woops. Links fixed

[92CXyD]

all but the third picture fail.

woops. Links fixed

There ya go.

Nice, any more picts. maybe more info on set-up?

[shogun]

you maybe shouldnt get so high in base pressure, at most 4.5 psi, does it have a working powervalve? you should check that on my datsun that made my car awful in low rpms but sweet on boost, but then again i had a boost referenced mechanical pump

[trevor72]

looks like an autolite 1v carb there...? 

the green breather is full of aids, its so ugly for one, and likely leaks like a dumb slut.

I'd say do more reading on the turbo forums (http://www.turbomustangs.com/) and read about boost referenced power valves. 

Is the carb completely stock? Does it fall on its face if you flick the throttle/stand on it at 50mph or does it do it when you roll into it at the same mph (load)? Does it clean up after tip in? go up a few jet sizes if it that lean at WOT!!

It could be that the pump shot is too small for all the quick spooling air that is rushing in on tip in at 50mph.  a 50cc pump shot might help or moving the cam for said pump shot to possition#2, if it has any adjustment (not sure-it looks similar to a holley kinda which is my reference).

a holley 2v 500cfm carb would do wonders for you. as would an elbow with a better positive seal (cheap and attainable for the holley).

[ryan1]

any updates on this, i might do a low buck, small turbo set on my carbed fairmont.

[Cadracer]

first you cant adjust anything for more fuel to handle your boost level  by outside of the carb. You need to go in a drill out the power valve orfice to flow more fuel.

[Ntrain2k]

first you cant adjust anything for more fuel to handle your boost level  by outside of the carb. You need to go in a drill out the power valve orfice to flow more fuel.

Boost referencing the FPR will add fuel under boost. Done on a ton of the JYT setups.

[trevor72]

first you cant adjust anything for more fuel to handle your boost level  by outside of the carb. You need to go in a drill out the power valve orfice to flow more fuel.

Boost referencing the FPR will add fuel under boost. Done on a ton of the JYT setups.

Will add more fuel pressure and push fuel out the bowl gaskets.  Nice try you tool.

generally speaking carbs have three circuits, idle, transition and WOT.  adjust the main jet accordingly. 

[dvst8r]

first you cant adjust anything for more fuel to handle your boost level  by outside of the carb. You need to go in a drill out the power valve orfice to flow more fuel.

Boost referencing the FPR will add fuel under boost. Done on a ton of the JYT setups.

Will add more fuel pressure and push fuel out the bowl gaskets.  Nice try you tool.

generally speaking carbs have three circuits, idle, transition and WOT.  adjust the main jet accordingly. 

Retard read what was written.

Boost referencing the FPR so with every 1psi of air pressure, you add 1psi of fuel pressure. Keeping things in equilibrium.

[trevor72]

Nigger please, read what i wrote.

You of all ppl should know no matter how hard you push if the hole is too small, the hole is too small. 

Use the Carb (jetting) to determine the fuel being delivered, and use the FPR for matching the demand for fuel at the bowl.

In any case the OP's issue was in transition/tip in iirc, and so the power valve/pump shot are what should be looked at.

[Ntrain2k]

Will add more fuel pressure and push fuel out the bowl gaskets.  Nice try you tool.

generally speaking carbs have three circuits, idle, transition and WOT.  adjust the main jet accordingly. 

Damn, don't tell that to the hundreds of guys doing it already and have been for years.

Tool, that's original.

 

[ryan1]

any updates on this?