tgilligan

Hey Guys,

Need some help. I'm replacing my stock 350 Rocket intake manifold with an Edelbrock Performer #3711 for my 70' Cutlass Supreme. It's a hot air choke, non-EGR application and I'm questioning the transition of fittings and sensors from old to new.

The port locations from the old to new do not match with the exception of the thermal vacuum switch and the temperature sensor. I have several brass 90 degree fittings that I pulled off the stock manifold that have no matching place on the new. Also the thread sizes don't fit, the stock ones are too small. Did Edelbrock simplify things and I don't need as many vacuum lines as I did before?

Lastly, there is a 1/2" port I don't have anything for so do I just plug it with a pipe plug? Same with a couple of small miscellaneous items, can I pipe plug those too?

hookem horns

Threads should be the same so maybe the old fittings are damaged or corroded. Manifold vacuum can come from any port, just figure out what you need with the new set-up plus you can use tees on the vacuum hoses if needed. Pipe plugs work on unused ports. On the choke, consider a block off plate and convert the carb to electric choke. I'm assuming factory correctness not highly important since you are not using the stock manifold.

oldcutlass

You will need to adapt the ports that you need and plug the ones you don't. They are all pipe thread. I use brass or ss fittings with plumbers pipe dope.

joe_padavano

There's noting magic about the location of these fittings, so long as you pay attention to a couple of rules.

1) Any coolant sensor must be in flowing coolant. That means the bungs in the water crossover on either side of the t-stat housing. Don't put a coolant sensor (or TVS, or similar device) in the bungs at the rear of the intake.

2) Any manifold vacuum port can go into a bung on any intake runner.

3) Any unused ports can be plugged with pipe plugs

4) Use bushings where the holes in the manifolds are larger than the fittings. You can get bushings in the plumping dept of any hardware or home improvement store. You may find that it's much cleaner to simply buy new fittings at an auto parts store with the correct thread, however.

RetroRanger

check your hood clearance before closing it as well IIRC that manifold is 2"? taller than stock

Lars

he's got the sbo version not bbo, I shure it's stock hight

Brandon871861

So I'm having the exact same issue. Except the new parts that go on the front and rear passenger side. The 1/2 plugs. That one plugs into the wire harness that has 3 ports and the back one that has the one. I don't know what either of those are called. When you get this complete, will you send updated pics and tell me what those parts are called? That way I know what to do. It would be greatly appreciated. I'm no mechanic and I could use all the help I can get. Thanks

tgilligan

This is an old thread so not sure if the mods will relocate this but I’ll help how I can. The port in the front is for the thermo vacuum switch which has ported vacuum lines and connects between the TCS solenoid and the manifold. I deleted this along with the solenoid and run the corresponding trans vacuum line directly to manifold vacuum. If you’re wanting to keep stock look and functionality, you should be able to find one used somewhat easily. For mine, I plugged that port as it’s not needed. For the port in the rear, that’s for the heater control valve. There’s a heater hose connected to it on one side and a vacuum line on the other. These can also be found new or used. Pics attached for reference.

Brandon871861

yea it helps some. I can't seem to figure what the two 1/4 ports that seem to have some sort of vaccum 90° copper fittings. I don't know what they go to. What else needs to be plugged either. I'll send pics in a day or so for reference of what I have done. Thank you for the help so far!!

Fun71

This may help.