440-3 Vacuum Pressure

[DaveVA78Chieftain]

Oh! I can answer that one!!  That is the vacuum line for the factory vacuum gauge.

Hmm, I do not think so or at least hope not.  That would be a ported vacuum line which does not indicate vacuum at idle.  If your stock gauge was a "Fuel Mileage" style gauge, not a regular vacuum gauge, then ported vacuum is OK to use.

[LJ-TJ]

Geeeeeezzzzzzzz Ok then which or what hose do I tap into. D:oH! D:oH! i??

[DaveVA78Chieftain]

Just get yourself a plastic t-fitting from the auto supply house and tap into the same place for both gauges.  This pak of fittings runs about $6 for 65 of them 

[Rickf1985]

I hate to be a wise a??    but, the simplest thing to do, is look at the vacuum hose routing diagrams in the emissions section of the Dodge MH Service manual.  Hint, Section 25.

Also, from 73 on, Dodge used ported vacuum advance.  One of those emissions thingy's.

I do not see an EGR valve (started in 75) in your pictures so these drawings should apply to you.  With EGR is a different set up that is contained in the 74-75 supplement.

I was hoping your "Wise azz" would be along to bail me out on this one. I fully admit I am not a Dodge man. When they came in the shop I just opened the manual and followed the specs. I did not do enough of them to memorize all that stuff. It is ironic because I did have a couple of police cars that were brought to me as "special projects" that the police department was working on. Special projects my aZZ! They had me build 426 hemis for these Monaco's that they had. I KNEW what they were for and warned all my buddies to watch out for them because they were scary fast. They ended up crashing both of them in just over a years time, almost killing one officer. End of project. Insurance company took the cars. I always wondered who ended up with the motors.

[LJ-TJ]

 :)rotflmao :)rotflmao A Hemis now there's an Idea. D:oH!

[Rickf1985]

It's "Hemi" TJ. Singular. I built two of them hence "hemis". You would only need one unless you really wanted to get exotic. W%

[Elandan2]

On my 440, the distributor gets full vacuum and the ported vacuum hose is connected to the canister.  That is why the vacuum gauge is teed into the distributor advance hose. I have read many articles about whether it should be "manifold" or "ported" and the end result always seems the same. After you're off idle, either port gives you full vacuum. The manufacturers switched to ported vacuum for the distributor to improve emissions at idle. The vapour canister has to have ported vacuum so that it doesn't begin to purge into the carb until the engine is off idle.  Rick

[Rickf1985]

Ported vacuum changes with the amount of throttle so you will almost never see full manifold vacuum at a ported fitting.

[Elandan2]

I Know that we have been around and around on this topic, but here is an interesting article explaining the difference between using ported and manifold vacuum for the distributor, and the effects at different throttle positions.


http://chevellestuff.net/tech/articles/vacuum/port_or_manifold.htm


Rick

[Rickf1985]

But you are comparing Chevy specs on a Dodge engine. Similar but different. Getting pretty far off the original subject now.

[Elandan2]

Yes, GM specs may be different than Mopar, but the principle doesn't change. I posted that particular article because it explains it in a simple way.

[Sasquatch]

Sorry to continue the off topic part, but I converted my 440 to manifold vacuum to the dist. years ago and will never go back.  Runs much better.