383 engine output

[Trusuavec]

Got a 383 stroker motor with a mild cam, 750 cfm holley . The engine idles great but doesn"t seem to get the car going with the torque that I think it should have. It smokes the tires almost in reverse, but will not even chirp with forward motion. The acceleration is not aggressive at all. It does not respond at all. to tuning the carb or timing changes. What do you guys think is up with this thing?

 

[turbonutter69]

How does it idle and rev?

 

[Trusuavec]

It revs and idles fine....does not perform under load(when accelerating......my wifes car would blow it away right now! (Trust me it just a family car) The 383 is just amazingly sluggish under hard acceleration. I forgot to say that I am suspecting the mechanical fuel pump. Its the original pump that fed the 1986 305 engine. I have no idea what its GPH or pressure rating is.

 

[indiaman]

First check your firing order, some leads may have been mixed up

 

[Trusuavec]

Firing order is all good 18436572. Believe me this thing lets you know when you have mixed leads up!

 

[indiaman]

You say the car is OK in reverse, If you have an Auto Transmission, it may not be starting in Low, is it a powerglide?

 

[Trusuavec]

I am fairly sure its starting in low gear...I can shift it manually and get the same result. Its the original THM-2004R transmission.

 

[indiaman]

OK, so your firing order is OK and your TH 200 starts in Low, Now look into the carbs with the engine off, open throttle and ensure that you can see two jets of gas spraying out. If this check too is OK Pull your plugs and check if they are sooty and black(running rich)

 

[Trusuavec]

Plugs are new...wires and distributor cap and rotor are new.

 

[indiaman]

OK,1) Now check if your exhaust manifold has leaks 2) Check Vacuum advance on the distributor
(maybe the connection is cracked or broken)
I assume that the 383 was rebuilt properly, now, if everything else checks out reasonably, I think that you may need a torque converter with a higher stall speed( More than 2800 RPM Stall speed.)

 

[indiaman]

Also, it may be that you need a smaller carburetter, try fitting a 650 CFM Holley

 

[Art Knigge]

I am running a 383 with good success. The 750 Holley should be appropriate. What differential gear do you have? What are your timingspecs? Compression?

 

[Trusuavec]

My compression tested out okay....150-160 psi on all cylinders. I have adjusted the timing from as much as I can go in either direction with the same results......trying to accelerate hard brings a popping sound and a serious bog down from the engine. I have changed the plugs, wires, ignition coil and adjusted the carb with no results.

 

[Art Knigge]

I guess I was not clear. I had similar problems. What is your compression ratio? What is your initial and full timing and at what RPM? How much vacuum advance do you have?

 

[ronniecalcutta]

Popping sound? there must be problem in the carb. Maybe a clog. Check your fuel filter. It can cause too due to improper adjustments of valve or misfires (i.e. timing).