Vacuum with 13* retard

[series8217]

Anyone else notice a significant decrease in idle/off throttle vacuum with the 13* exhaust cam retard? My brakes have been terrible while not engine braking ever since I put in my rebuilt motor with the 13* retard..

[SappySE107]

I raise my idle to 850 with the 13 degree retard. That might help as i know the stock idle is a bit low for it.

[series8217]

Well, the motor hovers at like 1100 or 1200 until I come to a stop anyway.. so I think something else is going on. I guess I ought to start looking for vacuum leaks then.

[Husky]

Does it drop down to normal Idle as soon as you come to a stop?

[HayesPerformance]

Hey series8217,

May I ask, what did you notice in the way of engine performance, etc with the Degree change? Give me a list of what differences you saw. Oh and did you put 96+ heads on a 95 older motor? I have a set of 96 heads that I want to install and then at the same time make the 13 degree change to BUT I'M DIEING TO KNOW WHAT TO EXPECT BEFORE I GO AHEAD WITH IT! THANKS!

Dave

[series8217]

Hey series8217,

May I ask, what did you notice in the way of engine performance, etc with the Degree change? Give me a list of what differences you saw. Oh and did you put 96+ heads on a 95 older motor? I have a set of 96 heads that I want to install and then at the same time make the 13 degree change to BUT I'M DIEING TO KNOW WHAT TO EXPECT BEFORE I GO AHEAD WITH IT! THANKS!

Dave

I wish I could comment on the changes in performance but I rebuilt the motor, decked the heads, balanced and blueprinted it, etc all at the same time.
What I can say: The idle is choppier due to the extra overlap. The powerband seems to have shifted up, it doesnt pull as hard until 3750 or 4000 now, and pulls to about 6500 or 6750.
I promise a dyno chart when I finish tuning the engine. It DOES need 10% or more extra fuel up there so I am sure some flow increased!

-Steven

Does it drop down to normal Idle as soon as you come to a stop?

Yes, at about 2 or 3 mph or stopped it will go back to idle.

[RednBlack]

Did you retard 13*, or go -6+6?

[HayesPerformance]

that was my thought

Yes, That I want to be sure of. So you did the usaual 7 advance on intake and 6 Degree retard on exhaust.

I have a automatic, So what is best for my car? I heard that for a auto go with +6 , -6.

Is that true?????????????????

Dave

[RednBlack]

Yep.

[series8217]

Re: that was my thought

Did you retard 13*, or go -6+6?

13 degree exhaust retard, buddy.

Yes, That I want to be sure of. So you did the usaual 7 advance on intake and 6 Degree retard on exhaust.

I have a automatic, So what is best for my car? I heard that for a auto go with +6 , -6.

Is that true?????????????????

Dave

I did the 13 degree exhaust retard.

AS for an automatic, I would go for the +6 intake -6 exhaust for an automatic, or just leave it stock.

[HayesPerformance]

oh ok

Oh ok,

That makes sense. Thanks.