Help with Smog stuff on 472
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500, 472, 425, 368 Discussion, Help with Smog stuff on 472 in Cadillac Engine Technical Discussion; Hey guys, I'm swapping a 472 into my 78 Caprice, and since it's so old, I won't have to do ...
  1. #1
    Guy1138's Avatar
    Guy1138 is offline Cadillac Owners Member
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    Help with Smog stuff on 472

    Hey guys,
    I'm swapping a 472 into my 78 Caprice, and since it's so old, I won't have to do inspections or emissions in most places. So, I want to remove the smog pump, which is currently off so I could get to the pass engine mount. Here are my questions:

    1. Can I just leave the pump off? Somebody said something about it being a tensioner, but it doesn't look like it on my car. Looks like it pretty much stands alone.

    2. What do I have to plug up? From the pump, a hose runs up to a T fitting and then into the front of both heads (or did it run into the valve covers, can't remember.)

    3. What about EGR, and what does that have to do with the smog pump? Is it possible that my motor never had EGR? The ports that look to be EGR ports on the exhaust ports of the heads seem to have bolts stuck in them.

    4. Is AIR the same as EGR, or does AIR refer to the smog pump?

    Thanks for your help guys!

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    Guy1138's Avatar
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    Re: Help with Smog stuff on 472

    Oh, duh, the engine is coming out of a 73 Deville

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    Re: Help with Smog stuff on 472

    We yanked all the smog stuff off my friends '75 dodge coronet and it had GM smog pump equipment. Yanked off the smog pump and belt (it's not a tensioner) took off that tube that went up near the intake manifold took out that whole rail that goes to the back of the Y pipe that hooks into both exhaust manifolds and took off the Y pipe cause he was going to put on headers anyways so it wouldn't matter. WE plugged up the EGR valve so nothing would go in there and yanked all vacumm lines that weren't needed. I Think that's all we did. We left the PCV on though cause that ones important and you don't want sludge. I think that's it.

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    lux hauler is offline Cadillac Owners Connoisseur
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    Re: Help with Smog stuff on 472

    The cross-over tube runs to the front of each head......those can be plugged. They make press-in plugs that fit.

    A.I.R. is the smog pump.

    You might have to change the pullys to the 425 (non A.I.R.) pullys. I can't say for sure because I don't have my engine that far along yet. I did get a set of 425 pullys (crank and water pump) though......I was told I would need them.

    My engine is out of a '72 Eldo so the A.I.R. pump was all I had.

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    Angela Desmond is offline Cadillac Owners Fanatic
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    Re: Help with Smog stuff on 472

    While you're on the subject of putting a 472 into a '78 Caprice, have you checked to see what oil pan you're going to use? I don't believe your 472 oil pan will clear the crossmember.

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    Angela Desmond is offline Cadillac Owners Fanatic
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    Re: Help with Smog stuff on 472

    Forgot to ask you what tranny is in the car. My '77 came with a TH200 or 250; I forget. Swapped it out for a TH350. If it's the 200 or 250, I don't think it will last under the torque of a 472 Caddy.

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    Guy1138's Avatar
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    Re: Help with Smog stuff on 472

    I guess this is getting a little off topic, but yes, I will absolutely need a rear sump oil pan. I called around today and yesterday, and there are apparently none currently available, although Flash may have some pricey new pans for sale soon. The pan is certainly an unexpected cost overrun in this project if I have to buy one. I'm going to call the yards around here next, but being in Hawaii certainly limits my choices!

    My tranny is a TH400 out of the donor car. I messed up the pan pretty good, so I figure I'll buy an aluminum one and take it to a tranny shop for a service, flush, inspection and a shift kit if it's in good enough shape!

    Are you swapping a Caddy Big Block into a GM B-body? That would be great, there are several people working on this project right now, the more the merrier!

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    Angela Desmond is offline Cadillac Owners Fanatic
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    Re: Help with Smog stuff on 472

    Yes, I'm putting a 425 into a '77 Caprice. I'm using a TH350 that we put in long ago. I modified the 425 with Ross 11:1 forged pistons, Eagle H-beam rods,(the ones for the Olds), cam has .565lift with the Ford FE cast rockers and ported iron heads. I'm going to try to make the 425 pan work but I haven't sized up the bay and block yet to see if it will work. If it does you may be able to go with the 425 mid-sump pan also. I'm going to try the Q-Jet with the Edelbrock performer manifold. Had to open up the runners a bit to match the head ports.Keep in touch how your engine fits in there. I'm very interested

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    Re: Help with Smog stuff on 472

    I'm not quite to the point of dropping the engine in yet, I am calling local yards tomorrow to find a pan, and I'll order the universal mounts from Flash this week most likely. Tomorrow I'll also get the heads off and check out the bores, which will determine how much of a refresh it needs. If the bores need honing, I'm going to drop some higher comp KB pistons in. If the cam and lifters are a bit messed up I'll install a slightly hotter cam, but mostly I'm leaing it alone. I figure if the bottom end is good, I can always add to the top when time and $$ allow. The Ebrock intake, head work and 100 shot of Nitrous will have to wait I guess

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    Angela Desmond is offline Cadillac Owners Fanatic
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    Re: Help with Smog stuff on 472

    Wait 'till you have all your money together for upgrades. One horsepower upgrade without the other(like a big cam and no porting) wont produce much power. Plus it's nice to know you have good parts in there; you'll sleep better for it..

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    Sasquatch's Avatar
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    Re: Help with Smog stuff on 472

    What does removing the smog pump do for overall performance? How is the belt configuration set up on your motor to drive the smog pump? I also have a 472 in a 69 hearse and I am suspiciuos that the belts aren't right. If the smog pump is eliminated will the standard water pump and pulley set up no longer work? (LUX) These are great motors to work on so I'm trying to learn all I can. I have a 69 Caddy shop manual on the way that I got off of ebay. That should answer a ton of questions. Thanks.

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    Angela Desmond is offline Cadillac Owners Fanatic
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    Re: Help with Smog stuff on 472

    The performance gained by removing the A.I.R. pump is through not losing the horsepower it takes to drive the pump. The air is injected into the exhaust manifold so it doesn't interfere with combustion, like the EGR does. How much HP it takes to drive the pump I don't know, but it also takes HP to drive the water pump , alternator, and power steering pump; but we sort of need those, don't we If you want to run headers you'll want to get rid of it anyway...

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