Vaccum numbers

[BLACK Ttype]

If ported heads and intake take less boost to move the same volume of air, does this also apply to vaccum?

I installed ported heads/intake and speedpro 204-214 cam, vac is 13 in N, 10 to 11 in D.
Seems a little low to me.

Any ideas on this theory?

 

[cool 84]

In my experience and I'm sure some will disagree, but the cam is the only thing that lowers vacuum. Mine with ported heads, intake, and the same cam pulled a good 17" in gear. It could possibly be that I have a 9.5" convertor that's looser than stock, less load at idle. Even so, 10-11 is very low even with a stock convertor. Mine pulls more than that cruising down the freeway. Does the car run good? Every car is different, my dad's car with the same basic combo and cam pulls 3 less in of vacuum than mine. Vacuum leak? Cam installed off? Bad tune? What do your BLM # look like?

 

[6SENSE]

How does the car idle? Is it smooth or loping/kind of rythmic? Any issues with backfiring from the intake?

 

[BLACK Ttype]

cool 84
Car runs ok. I wouldn't call it good.

I don't hear any vac leaks. I have sprayed carb cleaner around and can't find any leaks either.

What do you mean cam installed off? If your talkin' about the timing gears and chain, they are right.

Haven't tuned the car much yet. Just put it together the other day.

From what I can tell the BLM's stay around 130. It's hard to say, the el'cheapo scanner I have raises the rpms whenever it reads the ecm.


6SENSE
Car idles rough, but I think the IAC and TPS need to be reset. I'm gonna go do that here in a few minutes. I'll let you guys know more about that in a few.

No issues with back firing through the intake.

I've had it up to 17 lbs with only 3* of KR so far so thats not bad(I'm still trying to tune that KR away), its just the vac and idle concern me.

 

[BLACK Ttype]

Adjusted IAC and TPS.
Still Idling crappy w/ bad vaccum.
I think the piston rings are shot.(Slight amount of blue smoke in exaust)
Is it possible to change the rings from the bottom without pulling the heads?(I know dumb question, just hoping.)

Also, after adjusting IAC and TPS idle came back down to 550 but vac also went down to 11" at idle and 9" in gear.

 

[6SENSE]

Before worrying about the rings (even though blue smoke dont sound good) do a compression test.
The reason I was asking about idle quality is that along with the low vaccum its a sign of a cam with a bad lobe(s)/wiped cam. When I had my wiped Poston 202/202 cam my vac at idle was 8-9 in. in D and 12 in P/N. This was with a well adjusted IAC and a chip that didnt force my rpms up. As you have already discovered, with the rpms slightly higher the vac will be slightly higher.
I was able to run crazy amounts of boost (as high as 25lbs) on pump gas with very little to no KR. Performance was suffering though as it didnt make a difference whether I was running high or low boost, I would run the same #s. With the valves not opening like they should, I dont think I was moving as much air as I should have been, thus KR wasnt as much an issue as it would have been. Running rich was more of an issue than lean.
How did you go about breaking-in the cam?

 

[BLACK Ttype]

Not very well I guess
There was a problem with the break-in
When I first started it, I took it up to 2000 RPMs for about 3 seconds untill I noticed that there was no oil pressure. I shut it down, primed the pump w/ petrolium jelly. Restarted, ran at about 2000-2200 RPMs for 20-25 minutes.

 

[BLACK Ttype]

Anyone got a good cam they wanna sell?