3.6 Resonance Valve Non-Op

[Duc Hunter]

Since it seems there are very few folks on the 964 forum I am cross posting this here.


964 Forum Thread

I have been troubleshooting my RatRod's engine. I can either make it run well down low, and have it fall on its face up high, or have it run well up high and have it SUCK down low. After a new O2 sensor, and some other things the car i greatly improved. I rolled the car on a dyno just to see the AFR's, and see if that pointed me to anything else. Low and behold, it did.


The green run is "normal" and for the red run I held the resonance valve open by hand. We tried various vacuum sources and the valve never opens on its own.

This car, thanks to the 2 PO's who got the 3.6 swap about 80% complete before I bought the car (and got her running), did not put a vacuum reservoir in the car. I know it needs that to actuate the resonance valve (WOT throttle there is no vacuum from the manifold). Once that is in the car I will check my actuator valve with a hand vacuum pump to see if it moves.

How should the vacuum hoses be connected to the resonance valve actuator? I assume you would be;

• Vacuum source (manifold) to the resevoir
• Resevoir to the solenoid
• Solenoid to the actuator that moves the resonance valve

[smokintr6]

I'm learning about this right now for my 3.6 conversion. search pelican "964 vacuum" titles only. There are only a few threads. One of them shows the switch for the valve solenoid, and which hose goes down to the actuator. Not exactly sure how the vacuum reserve is hooked up... Your guess seems reasonable, but wouldn't you need a check valve to keep the tank from equalizing when the throttle is open?

Could you share some pictures of your intake and vacuum setup? I have seen mention of 3.6 swap cars getting rid of 100% of the vacuum things except the resonance flap. I would like to go the same way except keep the power brakes... assuming that its actually feasible.

[smokintr6]

I'm not quite in the car yet, so I have some time

[Duc Hunter]

Originally Posted by smokintr6

Your guess seems reasonable, but wouldn't you need a check valve to keep the tank from equalizing when the throttle is open?

Could you share some pictures of your intake and vacuum setup? I have seen mention of 3.6 swap cars getting rid of 100% of the vacuum things except the resonance flap. I would like to go the same way except keep the power brakes... assuming that its actually feasible.

I believe the check valve is in the tanks. There is what looks like a check valve between the manifold and the solenoid right now, but without a vacuum reservoir there would not be enough vacuum to actuate the resonance valve. My Indy may have a factory manual for a 864 that covered the vacuum system. He had the electrical so I can hope.

Mine is the the car, I will see if I can get a good shot once I figure int all out. Not sure there is a point to providing one now?

[smokintr6]

So, from what I deduced from the other posts, and what's still on my engine this is what I am 99.9% sure the correct configuration is. I made the image from my engine, where the previous owner removed the actuator for the flapper, so I don't have the complete picture.

[Duc Hunter]

smokintr6,

Does your car still run the vacuum reservoir? I would think it would be required as there is zero vacuum at WOT throttle and 5,000 RPM, which is when vacuum is needed to open the resonance valve? Otherwise your image looks great.

On second look, the light blue y......I believe the right hand line goes down to your vacuum reservoir. My guess is that the check valve allows that side to have vacuum when there is manifold vacuum. When you go WOT and eliminate manifold vacuum that check valve closes, and the reservoir supplies the vacuum to the systems through the light blue line, to the Y, through the solenoid. Sound right?

PS - TR6 is one of my favorite cars.

[Busta Rib]

I'm currently doing a 964 3.6 conversion in my car and your diagram matches what is on my engine. Scavenge a vacuum tank from a used intake assembly. I used the vacuum tank from the stock assembly from my engine. I installed a K&N cone filter.

Originally Posted by smokintr6

So, from what I deduced from the other posts, and what's still on my engine this is what I am 99.9% sure the correct configuration is. I made the image from my engine, where the previous owner removed the actuator for the flapper, so I don't have the complete picture.

[smokintr6]

I think the vacuum reservoir is one of the things the PO kept, but I haven't gone out to the barn to look at my airbox yet. You're right that I believe the blue tee goes to the tank, that hose in the photo is disconnected and draped over the manifold for the moment.

I grew up with British cars! The last car I did a ground up restoration on was a TR250 that I gave to my dad.

Originally Posted by Duc Hunter

smokintr6,

Does your car still run the vacuum reservoir? I would think it would be required as there is zero vacuum at WOT throttle and 5,000 RPM, which is when vacuum is needed to open the resonance valve? Otherwise your image looks great.

On second look, the light blue y......I believe the right hand line goes down to your vacuum reservoir. My guess is that the check valve allows that side to have vacuum when there is manifold vacuum. When you go WOT and eliminate manifold vacuum that check valve closes, and the reservoir supplies the vacuum to the systems through the light blue line, to the Y, through the solenoid. Sound right?

PS - TR6 is one of my favorite cars.

[smokintr6]

Thanks for the confirmation! After reading some posts I believe I'm going to delete every other vacuum connection except these parts for the flap. Was there anything else important that you kept?

Originally Posted by Busta Rib

I'm currently doing a 964 3.6 conversion in my car and your diagram matches what is on my engine. Scavenge a vacuum tank from a used intake assembly. I used the vacuum tank from the stock assembly from my engine. I installed

[Busta Rib]

I deleted/plugged the brake booster vacuum lines (2 in the diagram) as well. I'm keeping the gas tank ventilation hose. Keeping everything else stock for now. My primary focus is getting my engine started. I'll PM you. Would like to chat about your setup.

Originally Posted by smokintr6

Thanks for the confirmation! After reading some posts I believe I'm going to delete every other vacuum connection except these parts for the flap. Was there anything else important that you kept?

[Duc Hunter]

Just to close the loop on this. I installed a 2 port vacuum reservoir from Napa as a temporary measure (was $16). I ran the redline as is above. The light blue line runs from the check valve to one of the 2 ports on my reservoir. I ran the other line from my reservoir to the solenoid as the light blue line that comes out of the Y above does. I did not need a Y as I have a 2 port reservoir. The purple line on my car goes to the actuator. Wow did this wake up the engine above 5,000 RPM. Thank you for all of the help here! Amazing people!