When I step On it it Chokes

Xterminator03 · Sep 23, 2004

I have an 89 Gt with a carb, BIG cam, heads, and pulleys.
Every time I step on the Gas Hard the car chokes. It feels like it stop accelerationg for a second than it picks up. on couple of occations when just reving engine the carb flooded. With this Problem I can't get no instant power form my Pony. What could the Prblem be. One frined suggested it was the mettring jets. but I don't know I also cleaned the Carb but still same issue. Please Help. undefined

bmorrisj · Sep 23, 2004

accelerator pump ?

Xterminator03 · Sep 24, 2004

I dont think is no accelerator pump. When I say it chokes it feels like to much fuel compared to air is going in. Like i said if i just pump the gas and don't hold it the carb floods.

PhLoBuS · Sep 24, 2004

automatic or a standard?

Xterminator03 · Sep 24, 2004

It's a 5-Spd

11sec87 · Sep 24, 2004

how big is the carb?
what size power valve are you running?
how much vaccuum are you pulling?
whats your definition a "big cam"?
give us some specs and maybe we can help out.

later

Xterminator03 · Sep 25, 2004

Carb Holley 750
Camzilla Z303, Advertised Duration 290/290, Lift .552/.552,
Plus 1.7 Roller Rockers

how much vaccuum are you Pulling?" - -Dont Know
Eldelbrock Air Gap RPM
5 Spd King Cobra Clutch
I Forgot to Add World Roush 200 Heads They're Polished

Bill88Stang · Sep 25, 2004

thats too much cam especially with 1.7's if ther rest of the motor is stock and it has no head work.

SmockDoiley · Sep 26, 2004

First off, you combo is too large for your engine. 200 cc runners with a 302 is too much, and so is that cam. Lastly, your intake is too small to match with those heads. What the cc size for those chambers. As for it flooding, it could be the float adjustment or your needle and seats need to be changed. You should just get the car dynoed and it will fix your problems. You have what is called an off -idle bog which can be caused by being too lean or too rich, but it sounds like too much gas caused from the float adjustment. What do you mean its flooding. Like the car wont start, or you just see gas dumping into the intake from the bowl vents? We need more info. Adjust your floats correctly, and step down a few jets and let us know.

Xterminator03 · Sep 26, 2004

I Forgot to Add World Roush 200 Heads They're Polished, UnderDrive Pulleys, No Tensioner, No Smog, No A/C,
160 Degrees Thermostat,

SmockDoiley · Sep 26, 2004

That really doesnt help us in this situation. I asked for the c.c. size

_jb_ · Sep 26, 2004

My friend has an 82 Camaro, 357 carbed and the fuel pump has been changed to stop the hestitation it has when it floors it. Turns out the carb is too big.

battyice · Sep 26, 2004

Is this a problem that occured after your combo was together and running well? Or did you bolt everything together and these are the problems you're having now? If you just put it together than I would guess you're carb is simply out of tune rather than having a mechanical problem. 750cfm is on the large side for your combo IMO. As others have mentioned, make sure your float levels are adjusted correctly. Also, make sure the rest of your engine is in tune, the timing and advance curve need to be set properly before you try and trouble shoot the carb.

If you haven't already, I recommend you buy a Holley carb book. It will give you specific instructions on how to change the float levels and adjust the accelerator pump.

A few more questions: Did you buy the carb new? What size jets are you running? What power valve are you using? How large is the accelerator pump? -I think some 750 Holley's could be ordered with a 50cc accelerator pump, which would be way too large for a mildly built 302.

Finally, one of other posters asked an excellent question: How much vaccum is your engine pulling? If your cam is that big, and you're not pulling very much vaccum...and your carb has a power valve set for a "stock engine" your main jets will open far too early, causing a bog.

Edit: How much fuel pressure are you running?

sorry for all the random questions, but this problem should be easily solved with a bit more information.

Chetly · Sep 26, 2004

i say accelerator pump

Xterminator03 · Sep 26, 2004

The Heads Have a 64 cc in the Chambers, The Carb does have a 50cc Acelerator pump,
When first installed the set up was working fine but after about 2 weeks and 2 races it started happening. (This same exact setup was in my friends car; same parts with addition of MSD and exhaust and was running perfectly fine)
When I say it floods i mean it will not start. ( and the only way it does start after this is if I open the hood floor it and turn the key) This letting me understanf that I need more air.

SmockDoiley · Sep 26, 2004

Its definetely running too rich if your always flooding it. I still think your parts are too much for a stock 302. That cam and those heads are designed for high rpms which must be killing your bottom end, and your lowend power and torque. Also, a 64cc chamber is going to give you even less compression than stock which is already too low for a cam that size. You cant have any intake runner air velocity with sub 9 to 1 compression ratio and 200 cc intake runners. Screw the idle mixture screws in all the way, then back them out 2 turns, and step down a few jets. Check your throttle response. You want it to be crisp, and your idle shouldnt hang after the throttle has returned. Your exhaust shouldnt smell like a lawnmower either. Keep tuning till your rid of the off-idle bog, the idle returns directly after let off, it starts easily, and the exhaust smells decent. Also, what is your timing at?

SmockDoiley · Sep 26, 2004

Oh yeah, do you know how to adjust the floats?

Xterminator03 · Sep 26, 2004

SmockDoiley said:
Oh yeah, do you know how to adjust the floats?

No I don't Oh and thanks for all your help so far.

SmockDoiley · Sep 27, 2004

On top of each bowl there is a large screw head and lock nut. And on the side of the bowl there is a screw. Remove the side one so you can see into the bowl. By using the top screws, adjust them until the fuel level in the bowl is just touching the bottom of the hole you made by removing the screw on the side. You'll make this adjustment as the car is running and warmed up. Basically by screwing up or down that top screw, you are adjusting the height at which the bowl float shuts off the needle and seat to stop gas from entering the bowl. Too low, and you run out of gas as you are racing. Too high and you can run too rich, or gas can slosh out of the vent and flood the carb.

Xterminator03 · Sep 30, 2004

Thaks smockydoiley I will do this on friday. I hope it fixes the bog.

When I step On it it Chokes

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