What's the difference?

[DusterDaddy]

I am planning a project and asking a ton of questions in a lot of places.

Can anyone tell me how a 1974 4v stock mopar intake and a 1984 4v stock intake are different?

I know the 84 intake is a "smog" intake but what makes it different?

 

[67Dart273]

I'm not sure when EGR came into effect for all the US, but the first couple of years Mopar implemented EGR, there WAS NO actual control valve. You can only "tell" an early EGR equipped manifold by looking down to the floor of the intake through the carb mount. Ma simply "drilled some holes" in the bottom of the intake, allowing exhaust from the crossover to leak into the intake area.

Later ones, of course, had the obvious EGR valve on the rear corner.

http://www.forabodiesonly.com/mopar/showthread.php?t=162760

This drawing is out of the 72 shop manual

 

[RustyRatRod]

I'm not sure when EGR came into effect for all the US, but the first couple of years Mopar implemented EGR, there WAS NO actual control valve.

EGR came out in 1974. The EGR ports would have had to be the 1973 model year only. The 72 only had "bumps" cast in and the 71 had nothing but a flat surface. It's funny you bring this up because I had a 73 intake. It had the "EGR jets" in the bottom. I remover them both to inspect them and they were not jets at all, but pipe plugs. There was no hole in either one. I even scraped them clean to be sure. They looked like jets, because they were hollow in the inside, but with no holes in their floors. I believe they were factory pieces too, because they would have been standard pipe plugs if someone had replaced them. I always thought that was kinda strange.

 

[oldkimmer]

..........the thermostat housing is on an angle on 79 up and the thermostat is smaller.....no real gain either way..kim........

 

[DusterDaddy]

So if I wanted to run the 84 stock 360 motor I have with the stock intake, and I drilled tapped and plugged the egr ports on the heads, what would i need to do to the intake to be able to use a non egr 600 cfm holley carb?

 

[DusterDaddy]

I'm not sure when EGR came into effect for all the US, but the first couple of years Mopar implemented EGR, there WAS NO actual control valve. You can only "tell" an early EGR equipped manifold by looking down to the floor of the intake through the carb mount. Ma simply "drilled some holes" in the bottom of the intake, allowing exhaust from the crossover to leak into the intake area.

Later ones, of course, had the obvious EGR valve on the rear corner.

http://www.forabodiesonly.com/mopar/showthread.php?t=162760

This drawing is out of the 72 shop manual

After seeing 67Darts image, I'm thinking I'll need an iron intake off a 340 if I want to run my motor with a factory intake that is Non EGR.
Does anyone make an aftermarket intake that when painted will look similar to a factory intake?

 

[67Dart273]

EGR came out in 1974. The EGR ports would have had to be the 1973 model year only..

You seem to be contradicting yourself. If EGR came out in 74, then "EGR ports" in 73 would STILL have been "EGR," and furthermore, the diagram I posted was 72

It might well be that Cal eee foooornia had EGR before the U.S.

 

[alan627b]

Put an adapter on it to go from the square Holley pattern to the spreadbore pattern the manifold has. If you arent worried about exhaust heat in the manifold you can weld the egr passage shut or most gasket kits have a metal insert to plug them off... the removable plate on the topside of later mamifolds like yours can be blanked off with a fabbed plate or you might find the block off on a junkyard manifold. Found on both 2V and 4V intakes.
It might have the offset water neck which is handy (and nesessary) to use the later smaller AC compressor... I think only the Performer (not RPM or Air Gap) is the only aluminum 4V manifold to have this. FYI.

Trivia... the best flowing spreadbore stock manifold is the 1971 manifold.. this has the casting number 3512100. Stocker class drag guys supposedly used to pay extra for these. The 71 340 was the highest NHRA rated 340 short of the TA/6 Pak.. it had high compression and this manifold with the T-Quad..used to be NHRA factored at 310 or 315 HP opposed to the 68-70 340's factored to 300.
if you want to go aluminum, the non air gap Performer, the Wieand Stealth, or any dual plane manifold can be "sleeperized" with a good coat of paint.. if you are really dedicated, mill or grind off the brand name!

Paint the whole thing black, lie like a rug and tell everybody you yanked the engine out of a 1984 pickup.. they were black by that time..and hide the carb under a big stock air cleaner with a bunch of air holes drilled where they don't show...

That would make a good thread all it's own...

 

[RustyRatRod]

You seem to be contradicting yourself. If EGR came out in 74, then "EGR ports" in 73 would STILL have been "EGR," and furthermore, the diagram I posted was 72

It might well be that Cal eee foooornia had EGR before the U.S.

No, not at all. The EGR VALVE came out in 74. In 73 there were the EGR jets like you describe.

 

[RustyRatRod]

So if I wanted to run the 84 stock 360 motor I have with the stock intake, and I drilled tapped and plugged the egr ports on the heads, what would i need to do to the intake to be able to use a non egr 600 cfm holley carb?

What EGR ports on the heads?

 

[alan627b]

Correct me if I'm wrong but... the EGR ports in the heads... might also be considered the passage that flows exhaust gas under the carb pad to heat the intake. You could weld this shut in the heads.. or the intake..probably a bad idea in a cold climate. My 340 had them carboned shut and even after being cleaned out I never noticed a difference. If the intake has the EGR valve or the block off plate bolted to it and the gasket goes bad.. man will you hear it! Then it vents exhaust gas under your hood! Don't ask me how I know... LOL!

Now if he means in the intake....... and I think he does... he's talking about the "floor jets" in the floor of the manifold itself. Easy enough to pipe plug these, put a little Devcon or similar permanent type epoxy in them, and smooth them off once it's hardened.
Some intakes have the pad for these jets cast into them but not drilled .

Attached pic has the exhaust crossover circled... most of the aftermarket performance oriented heads don't even have one.

 

[alan627b]

http://omaha.craigslist.org/pts/2726991972.html

You can't see the floor but this manifold is the one I was talking about.. I have one in my garage too. Doesn't even have the EGR jet pad cast into it.. not really a big deal either way.. can't make that much difference.

Getting back to Dreamers original question... your 84 manifold might or might not have the EGR valve on it.. it might have a couple of extra passages drilled and tapped for extra vacuum taps.. the later things got, the more stuff ran off vacuum. Especially in luxury yachts and trucks. As far as the performance potential... probably close enough to even not to notice.
If you don't have a ton of accessories... use the simpler intake which is probably the 74. You could make a little difference by grinding off any lumps and bumps in the ports (don't go nuts) and/or gasket matching.. blocking off the EGR jets might make the intake charge a little cooler, blocking the crossover passage should cool it down a lot it just depends on what you have in mind to do with it..

FYI, the 4V manifolds require their own throttle cable/kickdown bracket as they are a little taller to clear the larger runners in the 4V manifold.. or you can do a little cutting and welding if you are handy that way.. or buy one aftermarket.
Sorry for the long posts.. hope this helps.

Anybody remember the days when you could hardly find a stock 4V manifold in the junkyards to hop up your poor old 318? I do!
But you'd trip over ones for an SBC in every junk yard you came across...

Alan

 

[DusterDaddy]

I am talking about the smog ports just under the exhaust ports on the heads that the smog tubes get their exhaust from.

 

[cudamark]

Those are for the smog pump.....have nothing to do with EGR. The '74 360 4bbl intake will have slightly bigger intake ports than the '84 and as mentioned, the thermostat components are different. EGR came out in '72 in Ca. in the form off floor jets that metered exhaust gasses into the intake through a small oriface in a metal fitting threaded inside the manifold. '73 started an actual valve operated by vacuum. It was stock on all Ca. vehicles except the 340. Many 49 state vehicles came with a block-off plate and minimal smog for several years but eventually all states used this system. Even on EGR valved vehicles, many also have floor jets (or what looks like them anyway). Just look down the intake of any mid-70's and up intake and you should be able to see them. They don't seem to do much as I've removed them and replaced them with plugs and it doesn't seem to change the way the engine runs.

 

[cudamark]

http://omaha.craigslist.org/pts/2726991972.html

You can't see the floor but this manifold is the one I was talking about.. I have one in my garage too. Doesn't even have the EGR jet pad cast into it.. not really a big deal either way.. can't make that much difference.

Getting back to Dreamers original question... your 84 manifold might or might not have the EGR valve on it.. it might have a couple of extra passages drilled and tapped for extra vacuum taps.. the later things got, the more stuff ran off vacuum. Especially in luxury yachts and trucks. As far as the performance potential... probably close enough to even not to notice.
If you don't have a ton of accessories... use the simpler intake which is probably the 74. You could make a little difference by grinding off any lumps and bumps in the ports (don't go nuts) and/or gasket matching.. blocking off the EGR jets might make the intake charge a little cooler, blocking the crossover passage should cool it down a lot it just depends on what you have in mind to do with it..

FYI, the 4V manifolds require their own throttle cable/kickdown bracket as they are a little taller to clear the larger runners in the 4V manifold.. or you can do a little cutting and welding if you are handy that way.. or buy one aftermarket.
Sorry for the long posts.. hope this helps.

Anybody remember the days when you could hardly find a stock 4V manifold in the junkyards to hop up your poor old 318? I do!
But you'd trip over ones for an SBC in every junk yard you came across...

Alan

That's a 340 intake. All the factory 360 4bbl intakes have provision for an EGR valve.

 

[DusterDaddy]

Thats what I needed to know, Thanks!

 

[alan627b]

The air injector ports could be filled with some small allen head screws and epoxy.. and also probably filled in with Devcon or similar material. Some exhaust manifolds or headers may leave them uncovered and I'm not sure if that would cause any problems or not.
Also thanks to Cudamark for adding/clarifying to what I posted.. I forgot we were talking 360's not 340's.. it was late...

 

[RustyRatRod]

I simply tap the air injection holes to 1/4" and screw allen head set screws in with permatex high temp red on them. Works good.