engine dumping out at higher rpms? - Third Generation F-Body Message Boards

tjohnson320 · 09-14-2009, 04:32 PM

I have an 84 camaro that was originally a berlinetta. I put a brand new carburated 350 in it last year with a holley 650 double pumper on it. the engine starts, runs, and cruises all day long with no problems but as soon as i drop a gear and hammer on it, it will run up to about 4000 rpms and fall on its face. If i let out of the throttle and shift up again its fine but sometimes i have to feather it back to life. I have a mallory electric fuel pump back by the tank that feeds an edelbrock high flow, high performance mechanical fuel pump that feeds the carb. the reason for this was because i thought it was running out of fuel and still do, i just have no idea where. I hooked up to the original fuel lines out of the tank to feed the new fuel pumps. the return line is plugged and the black canister up front is still hooked up. any ideas would be greatly appreciated.

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five7kid · 09-14-2009, 05:50 PM

Welcome aboard thirdgen.org.

Tell us more about the engine itself, and what you put on it like exhaust and distributor.

tjohnson320 · 09-15-2009, 09:08 AM

The engine i had put in the car is a mid 90s block 350. It has vortec heads and intake and i have an first generation hei accel distributor for my ignition system. the engine puts out about 330 horse and about 330 foot pounds of torque. the exhaust system could be better but with the subframe connectors i went with, they totally blocked off where the exhaust should run. right now the exhaust consists of shorty headers that go into one pipe that runs back to the muffler which splits it into duals again that exit the car out the back. any advice about good exhaust systems for these 3rd gen camaros would be appreciated on my behalf also. ive read some other threads about guys switching from tpi to carbs and it sound like they have to do some work with the existing fuel pump in the car. does this sound like something i will probably have to do? if so then what?

five7kid · 09-15-2009, 03:06 PM

Can you run it up beyond 4000 RPMs at less than full throttle?

330 HP sounds like more than stock Vortec truck cam. What cam? Any work to the heads, like aftermarket valve springs?

For exhaust, look for the '86-'90 TPI single cat application stuff. Headers & y-pipe (Hooker 2055HKR fits the bill nicely, or search for member Dyno Don, who custom makes very nice headers & y-pipe for our cars), cat (like Catco 9118), and 3" cat-back.

tjohnson320 · 09-17-2009, 09:02 AM

the engine doesnt have a stock truck cam in it, its a little more aggresive but still idles fairly smooth. the car has hydraulic lifters and as for valve spring work i dont know. forgive me for the lack of engine info but i had the engine built for me and dont have the spec sheet in front of me. i can run the engine up to 4000 rpms with being full throttle. i also noticed over the weekend that the car mostly acts up after it has been running for a while and everything is up to running temp. does this sound like vapor lock? i also have no regulator in the fuel line and no return fuel line. could this also be causing my problems?

tjohnson320 · 09-17-2009, 09:05 AM

i meant that i can run the engine up to 4000 rpms without being at full throttle

Ozz1967 · 09-17-2009, 02:48 PM

I had this problem when I went with a 350 and used my stock carb. When I would hammer it the car would fall flat on it's face at 3800 RPM or so. For my Qjet, I had to put larger secondary metering rods in to allow more fuel to the motor.

So, Check your fuel pressure level. When you are getting on it, basically you are draining the fuel bowls faster than they can fill up. The 350 is a lot hungrier than the 305 ever was, especially running 330hp. I would check your fuel pressure going to the carb (coming from your fuel pump, do you use a regulator?), it should be set to a min of 6lbs, 6.5 or 7 is better but DO NOT GO OVER 7 or you'll flood the carb. Hope this helps!