Vacuum leak?

[STSFCTN67]

I have a friend that is having trouble with the vacuum in his 68 Cougar with a 302. It was rebuilt with late model goodies 3years ago and still the vacuum is at 14.5 at idle. It is basically a late model 90's 302 with an x303 cam and a Performer intake and Holly 600 carb.

I have put my hands over the carb and I do not hear leaks and it dies quickly. I have sprayed starter fluid around the intake and there has been no change in RPM. Is there any other shade tree methods to check for a vacuum leak that I am missing?

 

[kilgorq]

I have a friend that is having trouble with the vacuum in his 68 Cougar with a 302. It was rebuilt with late model goodies 3years ago and still the vacuum is at 14.5 at idle. It is basically a late model 90's 302 with an x303 cam and a Performer intake and Holly 600 carb.

I have put my hands over the carb and I do not hear leaks and it dies quickly. I have sprayed starter fluid around the intake and there has been no change in RPM. Is there any other shade tree methods to check for a vacuum leak that I am missing?

14 to 15 is probably fairly normal for that cam at your elevation. (This is an acceptable vacuum at an idle of about 900 rpm.)
Verify your timing. If your timing is off (retarded too far) it will cause a low vacuum at idle.
But on a stock 302 the vacuum at idle is 16-17 so having the X303 cam in it will reduce that slightly.