In depth procedure for removing AIR pumps and related vacuum tubing

[hemi354az]

Perhaps some of the contributors on this thread should explain the difference between absolute gage pressure and common gage pressure.
0 ain't always 0.

[TripleJ]

In before the Bin!!

[Rickf1985]

Perhaps some of the contributors on this thread should explain the difference between absolute gage pressure and common gage pressure.
0 ain't always 0.

We are talking carbureted engines so Manifold Absolute Pressures really don't fall into this category. And Dave, I see the confusing part gotcha! Go back and you will see that I said manifold pressure of 18 at idle but I said 14.5 at WOT for ported. I use 14.5 because you will never achieve 100% efficiency on the intake plus it is only 14.7 at sea level.

I don't think we have strayed since this is all related to the removal of vacuum devices and related performance hits on the engine.

[JerryP]

So are all the hotrod/custom car/car builder guys wrong about plugging the distributor vacuum into the ported vacuum???

[legomybago]

So are all the hotrod/custom car/car builder guys wrong about plugging the distributor vacuum into the ported vacuum???

No...Your stock carbureted motorhome 454 runs off of ported vacuum.

[Rickf1985]

I think I am going to give up on this one. Everything originally runs through the TVS on the thermostat housing and it can get pretty complicated to try to explain every detail of what vacuum is doing what at any given point in time on a stock motor.

[JerryP]

I think I am going to give up on this one. Everything originally runs through the TVS on the thermostat housing and it can get pretty complicated to try to explain every detail of what vacuum is doing what at any given point in time on a stock motor.

Please do not, I see your point, about the advance set up to work with a bunch of other equipment.
Just not sure how that impacts when all that equipment is gone.

[M & J]

LOL Rick....

[Rickf1985]

I have explained that several times. I suggest you just try what you were going to do and see how it works. Maybe the Hot Rod guys are right and I am wrong. All of the monster motors I have built that used ported vacuum were in street racers. The other big blocks I have built were mileage motors and used manifold vacuum and custom curved distributors.

[Rickf1985]

See that, you are relearning already. This is NOT a hot rod, it is a truck.

Now, We are starting to talk about mileage and performance so I think the conversation is starting to stray off coarse a bit now. I am going to sign off with this statement and suggest you start a different thread on the performance aspect. It takes more power to get better mileage, that is contrary to what you may think but it is a fact. It is all in HOW the power is used.

[cncsparky]

No...Your stock carbureted motorhome 454 runs off of ported vacuum.

Correct, unless you have modified the distributor curve as I have, best to leave it stock. But, there are huge benefits to getting the timing corrected if you don't have to worry about emissions tests.

http://www.classicwinnebagos.com/forum/index.php/topic,9139.msg50770.html#msg50770

[Brob]

Hello everyone.  I realize I'm dredging up a 5 year old thread, but I am at a point on my 1987 P30 (7.4l) where I am reassembling the top end after a fuel leak caused a fire on the intake.  All of the spaghetti vacuum lines on the intake were burned up and have prompted me to undertake the removal of the AIR system entirely.  I am replacing the stock intake with an Edelbrock Performer 2-0 and a freshly rebuilt 800 cfm Quadrajet carburetor. 

My plan is to use manifold vacuum for the advance and to recurve the distributor.  I'm assuming I should hook the charcoal canister up to the carburetor vacuum.  I also am assuming that I should hook the transmission module (TH400) up to the manifold vacuum. 

Any guidance would be greatly appreciated.

[Rickf1985]

The transmission vacuum line has to be hooked up to manifold vacuum, a large enough one for roper signal. The charcoal canisters will be hooked up to ported vacuum and also to the air cleaner. There is a vacuum diagram on the side of the stock air cleaner showing all of the emissions lines. You will need to reinstall the TVS valve in the coolant line in the manifold since a lot of stuff works off of that. If you plan to run the advance on manifold vacuum there is a lot more to it than just hooking a line to the manifold. You will need to reset initial timing, reconfigure the distributor to limit total timing o the advance and also need to reconfigure the centrifugal advance. I strongly advise people to just go to DUI and buy a distributor from them and they will set the curve specifically for your vehicle.


https://performancedistributors.com/product/chevrolet-streetstrip-dui/