Help! 350 problem

[porboy]

Hello All,
My brand new 350 crate motor from GM is giving me some problems. Occasionaly when I have been driving for awhile and the burb is warm the motor starts to cut out and and the burb lunges forward. This only occurrs when the car is hot and I am in third(actually second if you don't count low) gear(sm465) around 3000 to 3500 rpm. If I shift into 4 it goes away. The only thing I can think of is either vapor lock caused by the heat from uncoated headers or the distribitor cutting out. What do you guys think? Everything on the motor is new except the distibtor. /forums/images/graemlins/1zhelp.gif

 

[sdavid]

Does it always happen at that RPM? Could be a bad fuel pump. I had a 350V8 that would do that at higher rpms in second gear (TH350) and it would feel like it was lunging or nose diving. It was a bad fuel pump, but it only did it at that RPM. I guess it was in the early stages of going out.

 

[porboy]

Yeah, it seems to only do it at that rpm range. The weird thing is is that it only does it after hard driving or when the motor is hot(above 190). The fuel pump probably only has about 10,000 miles on it.

 

[sdavid]

I guess the only way to really tell is to do a pressure test on it. Furds have had problems with vapor lock that I have been around, but not GMs. Could it be sucking air into the fuel lines any where?

 

[Rasberry]

What year Burb is it? I know someone with the same problem in his 89' and he had some dirty injectors. Cleaned them out and its fine now.

 

[porboy]

My burb is a 75. No injectors for me. I am going to do a little investigating when I get home. Maybe wrap the fuel line in some heat shield. Is there any way to test for an intermitant distributor?