i have a 1985 Iroc that had a 305 but i just switched it out for a 350 wit a medium cam. it came out of a truck that was used for racin and was just rebuilt. my problem is that the engine surges wit the rpms. it will idle low then idle high then stay stedy and when u think its fine u put it in reverse or drive and it dies. could this be a vacum problem. i have checked everything its like its not creating enough vacume. cause the breaks are sluggish or not like they used to be. i kno the cam will not create enough vacume but wat else could be the problem and is there a way to get more vacume

and wat connects to the flying saucer lookin thing under the plemum. i have my air stuff removed

i also have an overheatin problem the system has been flushed cause i just put the new engine in. the gauge goes to 260 in about 10 mins of runnin. i wired the fan to come on when i start the car but that didnt help. i have also added water wetter stuff by redline and that didnt help. the theromstat has been changed also. its a 185 i think should i go wit a 170 or something lower.

sry for the long post but i need some help have been tryin to figure it out for about a week now and about to give up and sell it as parts lol well maybe not sell it. thanks in advance

 

You can increase vacuum by shortening the duration of the valve openings, or altering the valve timing. That's usually easiest accomplished by changing hte cam to something more appropriate for a street engine, especially with a TPI.