Vacuum questions

[95gtdude]

I put a Vacuum gage on the beast today and it ran at 11 inches Hg. now from what I've been told that is way too low. I took the PCV out and pluged it up and unpluged to see if it would change the vacuum and it wasn't that much of a change. Does any body know where it is suppose to run exactly and how I can get it there?

 

[Bosko5.0]

Does any body know where it is suppose to run exactly and how I can get it there?

Where whats suppose to run???

Usually with a different cam you will get lower vaccum readings.

when you take the readings do it stay at a constant pressure or does it bounce around?

 

[95gtdude]

It bounces around a bit when first starting it but after warming up til stay right at 11in Hg with little flux

 

[Yellow302]

What I did since i tune my own is reduce the amount the IAC is alowed to open. They sell peices of metal that are called restricter plates.

at idle im up to about 12-14 from 8-10 vacum. Once im driving anything above 1k im at 18-22 vaccume.

You could also try to get some cheap gasket sheets and trace the one on there and make a smaller opening. cheapest way to go.

Make sure you run a cap on your oil fill neck if you pcv valve is connected to your intake. If not cap your pcv was acting as a leak when i had the breater and pvc connected.

 

[Stanger007]

Stock cammed engines run 18-22. You've got the stage 1 cam which has a bit of a lope but I would think that you would be much closer to 18-22 than 11.

Check for vacuum leaks - did you plug all the holes in the trickflow intake? Seems like there were a million of them I had to plug.

Wes

 

[final5-0]

Heck Fire

Now you got me wondering

I ain't had a v gauge on any of my combos
since I got back in this hobby in 97

Its still up in the attic somewhere

Wonder if it still works

Grady

 

[HISSIN50]

I agree - something is very wrong Tell us exactly how the readings vary (fluctuate), as you can make inferences from exactly what the gauge is doing.

You gotta love the vac gauge (they really are very useful).

 

[95gtdude]

Stock cammed engines run 18-22. You've got the stage 1 cam which has a bit of a lope but I would think that you would be much closer to 18-22 than 11.

Check for vacuum leaks - did you plug all the holes in the trickflow intake? Seems like there were a million of them I had to plug.

Wes

Yeah as far as I know I have no v-leaks anywhere on the manifold.

 

[95gtdude]

I agree - something is very wrong Tell us exactly how the readings vary (fluctuate), as you can make inferences from exactly what the gauge is doing.

You gotta love the vac gauge (they really are very useful).

well like I said it bounces between 11 and 13 inches Hg when starting cold and after warming up it'll stablize at 11 and move just a little (seems to move slightly with the cam lope)

 

[HISSIN50]

well like I said it bounces between 11 and 13 inches Hg when starting cold and after warming up it'll stablize at 11 and move just a little (seems to move slightly with the cam lope)

Speaking for the oscillation, this kinda sounds like you have a miss or an issue with a valve.

 

[95gtdude]

So what do I do to fix the problem?

 

[HISSIN50]

So what do I do to fix the problem?

Because vacuum diagnostics are tough to convey over a keyboard, I did some digging and think this link might help.
Otherwise, I'd be doing a leakdown test.

Good luck.

 

[95gtdude]

Because vacuum diagnostics are tough to convey over a keyboard, I did some digging and think this link might help.
Otherwise, I'd be doing a leakdown test.

Good luck.

Thanks Hissin!