Low Vacuum 302

Reply Subscribe

Thread Tools

Search this Thread

Feb 24, 2024 | 08:55 AM

Mjac167

Thread Starter

Mountain Pass

Joined: May 2018

Posts: 217

Likes: 12

Low Vacuum 302

I have a steady (no bouncing or swinging’ low vacuum reading of 10-12 inches on a 302. After checking very thoroughly for external leaks and finding none, I am trying to find out if I have an internal vacuum leak before I pull the manifold. I thought it might be a valve adjustment but was told almost all 302s have pedestal mounted rockers and are not adjustable, you just torque them down to specifications. Can those rockers be so out of torque right now that they are causing problems and any other ideas I can use to narrow down the steady low vacuum to an internal leak around the manifold seal.

Thanks
mjac

Feb 24, 2024 | 03:05 PM

wwhite

Logistics Pro

Joined: Aug 2014

Posts: 3,559

Likes: 852

What cam is in it?
do a compression test, post the results.

Feb 24, 2024 | 06:06 PM

Mjac167

Thread Starter

Mountain Pass

Joined: May 2018

Posts: 217

Likes: 12

It was called a Stage 1 Melling Cam, some people called it an RV Cam.

I was fixing to do a static compression test and even a running compression test but I did not know if it does have an internal vacuum leak from a bad manifold seal if those compression tests would be any good and from what I understand, the compression tests would diagnose a cracked ring, stuck valve or valve not seating or rounded cam lobes. But if I had any of those the vacuum gauge would be wildly bouncing or swinging and my vacuum readings are steady and 10-12 inches.

Thanks
mjac