I have a 383 in my 87 d-100 short box.I have replaced the following Dist, coil ignition module complete tune up etc.About the truck. Brought it from storage [sitting ]for 2 years. Carb was a mess ,cleaned the carb and put a carb kit in.My problem is that this truck should snap you neck right off the line but it just boggs first.It has a 727 tranny with shift kit and a very low speed rear end.It has a 600cfm carb a cam and punched out 0.60 over.Would a bigger carb do the trick maybe a 750 cfm????

 

Nope. How do you know the carb is not still dirty? That is, something, some passage plugged?

How about ignition advance? Have you checked what the mechanical advance is doing?

Describe the "bog" further: Is this just off idle, OK at medium speed, high speed? A general lack of power throughout the RPM range?

Have you checked is the accelerator pump working?

What about the general shape, overall of the engine?

Is it possible the timing chain/ sprockets are worn/ have slipped time?

Compression? Mileage on the engine?

 

Thanks for all the tips I will check everything you suggest ,maybe the carb is still dirty.I guess i should take it somewhere to have it cleaned and set up

 

what type of carb do you have ? a better carb may very well help 750 on a 383 is about the right size I would use a Proform or Holley type carb . The ign could be a problem as well as suggested .

 

If it has sat for awhile a vacum gauge will give you good info before tearing things apart and changing parts. A compression test is easy too. Both are inexpensive diagnostic tools. Check your timing (no vacum) at idle and say 3000rpm, record all the basic info and you'll probably get your answer, or report back and we'll help out.

 

Yea check the compression first. A good motor will produce 110 lbs and up at sea level. Also make sure there are no large variations between cylinders. If compression is low, it wont run no matter what you do to it.