472 installed but.....
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500, 472, 425, 368 Discussion, 472 installed but..... in Cadillac Engine Technical Discussion; I was finaly able to install that 472 I had into my 77SDV over this weekend however I now have ...
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    Unhappy 472 installed but.....

    I was finaly able to install that 472 I had into my 77SDV over this weekend however I now have some problems the car idles ok around 800+rpms in park when you shift into drive it drops to around 650-700 and idles rough it wont die but it doesn't idle smooth like it should. Now this engine was not a complete rebuild this is all that was done to it, new timing chain, new lifters, new gaskets, heads removed dissasembled cleaned and reasembled with new seals, new brass freeze plugs, the carburetor and fuel pump from the 425 were used now I'm thinking that the air fuel mix may be the cause but I don't know anything about changing that stuff also a HEI dist was used with plugs gaped to .060 I think that could also be something to look at I've checked and rechecked all vacuume lines and there all hooked up good and since I used the crank pully from the 425 timing was a pain to adjust and theres no markings to line up but I did set the timing to what I belive to be correct also theres no exhaust after the y pipe could this also be the cause
    any help is very much appreciated I just want this thing to idle like the old 425

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    Re: 472 installed but.....

    First, get that timing set where you know the advance. There should be a mark of some sort to set the timing by a timing light. Remember to disconnect and plug the vac advance line when setting timing if you have it on full time advance.

    You're sure the timing chain was installed correctly? (just checking)


    You'll also need to readjust the idle if the carb came from the 425:

    Get a vacuum gauge and hook it up to a vacuum port that reads vacuum at idle. Set the trans in drive at 50 rpm or so above the desired idle RPM, and note the vacuum reading.

    Next, turn both idle mixture needles 1/2 turn. At this point it doesn't matter which way, just turn both the same way. Note the change in the vacuum reading. If the vacuum has worsened, turn them back a full turn the other way and check the vacuum. OTOH, if the vacuum improved, recheck the idle RPM and then turn them another 1/2 turn the same way. Continue like this untill you cannot improve the idle vacuum further. Remember to reset the RPM after each time you turn the mixture screws.

    The final step is a 'lean drop'. Turn the screws in each 1/4 turn at a time untill the RPM's drop by those 50 rpm you had them above the desired idle. This leans out the idle fuel mixture for better fuel economy.

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    Re: 472 installed but.....

    thanks for the info but I was unable to find a vacuum gage yet I'll be going to some other stores later this week how ever I did get that exhaust fixed then went to messing with the timing again I'm useing the pully and marker from the 425 the best I can figure to line them up at is 18* btdc which is very close if not right on 5* BTDC with the old pully and marker but I am unable to turn the dist any futher clockwise because the vacuum advance hits the manifold right now its at ~24* and one other thing I found is that #1 is not firing at least I think so I pulled the plug while it was running and nothing changed in the idle or sound and I checked the spark plug and it didn't have any carbon on it like the others but it did look like it was firing just maybe not very well I don't know how to tell if its firing and if its not how to get it to. In order to fix the vacuum thing I ordered an ajustable vacuum advance kit from summit http://store.summitracing.com/partde...0&autoview=sku any help on the cylinder not firing will be very much appreciated

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    Re: 472 installed but.....

    What, no-one has a vacuum gauge? Geez, come out to the small towns here in Idaho! I think I got mine at NAPA or Sears. Also has an attachment for checking fuel pump pressure.

    You can find TDC on the motor and re-mark the crank pulley. You'd need a piston stop, then remove all the plugs (to make it easy to turn the motor over) and the passengers side valve cover. Turn the motor over untill you see the #1 intake valve close, then use the piston stop on the #1 cylinder to tell when the piston is at its very highest position.

    As far as the cylinder not firing, you're on the right track by pulling the plug wire with the motor running. Once the plug boot is off, stick a socket extension in where the plug was, or a spare sparkplug. Then, hold the end near the engine. About 1/8" away and you should see the spark if there is any. Be careful and try not to touch the car while doing this or else you will FEEL the spark. It's not bad really but can be a bit - hehe - shocking.

    Since the other cylinders are firing (obviously) I'd suspect a bad plug wire or a damaged terminal inside the distributor cap.

    Also, re-check the firing order. It can't hurt.

    To turn the distributor further, you can move the distributor by a tooth or two. Remove the cap and set it aside (leave the plug wires attached - saves time) then remove the distributor hold down bolt and carefully pull the distributor out of the motor. The rotor will turn slightly as you do this. Mark the location that the rotor ends up pointing at.
    Next, take a long flat-bladed screwdriver and using a flashlight, use the screwdriver to turn the distributor driveshaft slightly *counter-clockwise*. Now, turn the rotor the same amount counter clockwise and carefully slide the distributor back into the motor. If you did everything really well, the dist driveshaft will engage on the first try. If the distributor does not seat all the way down, it did not engage and you will have to pull the distributor out again and move the diriveshaft slightly one way or the other to get it to drop in.
    Once the distributor is back in and seated properly, turn the distributor body so the mark you made lines up with the rotor. Now clamp the dist down and put the cap back on. The timing should be about where it was before, but you will be able to turn the distributor farther now.

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    Re: 472 installed but.....

    well its definently the #1 cylinder not firing I replaced the wires and the spark plug and still nothing last night when I removed the plug from #1 at the dist cap I could see the spark jumping to the wire could it still be the cap terminal I dont know where to start to try to fix the problem. thanks for the help so far.

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    Re: 472 installed but.....

    well I replaced the old wires with accell supper stock 8mm wires put that #1 spark plug near the exhaust manifold and it had a very good big spark so I guess its firing I got it idleing good around 800+RPM so I figure its a mix between that timeing and air/fuel ratio. But could the air/fuel being off cause the engine to idle rough at around 600rpm

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    Re: 472 installed but.....

    Okay, so you've definately got spark at #1. If removing the #1 wire still makes no difference, I'd say you either have a dead cylinder, or the firing order is incorrect. May be time for a compression check.

    Just to check, the #1 cylinder is passengers front, firing order is 1-5-6-3-4-2-7-8.

    Yes, having the A/F ratio off would make for a bad idle. It is probably on the lean side, but that's where tuning with the vacuum gauge will tell you for sure which way the motor wants the mixture to go. You can probably get a rough tune just by ear using the same technique I described above with the vacuum gauge. Without the vacuum reading, you will be looking for the idle quality to improve, or RPM's to increase when you turn the mixture screws.

    Another quick check - both mixture screws are the same number of turns out, right?

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    Re: 472 installed but.....

    ok I got the vacuum gage however with that timeing being off still I couldn't get and accurite reading it was idleing around 800rpm and the vacuum gage was jumping rapidly between ~17 and 22 hg except if I sped the engine up to about 1400rpm it would stay steady around 17 or 18 which the instructions I got with it say that a fast variation at idle means worn valve guides but that doesn't seem possible on an engine with 47k mi and I did and quick little compression test on #1 by placeing my finger over the spark plug hole while someone cranked the engine over and it seamed strong how ever I'll try to get a compression tester one more thing about that vacuum gage I reved the engine and the vac dropped to ~10 hg then jumped back up to ~23 which thats supposed to mean good rings. I'm just waiting till I get that vacuum adjust kit before I make any assumptions as to bad valve guides. Thank you very much for you help so far.

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    Re: 472 installed but.....

    Unless you know the mileage of the donor car for an absolute fact, I wouldn't be surprised if that 47K is really 147K or more. These cars were built well, and if reasonably taken care of they don't show their age like most other cars of the same vintage.

    One other thing that could cause the idle vacuum to fluctuate like that - is your vacuum advance hooked to full manifold or ported vacuum? If it is on full manifold, try moving it to ported and see if that helps.

    Depending on the advance can you have, full manifold vacuum might not be enough to fully pull in the cannister. With the position of the vacuum advance kinda floating in the middle it tends to vary slightly which varies the timing advance and will cause the idle RPM and vacuum level to fluctuate as well. Naturally, this will change the position of the vacuum cannister causing even more fluctuation...

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    Re: 472 installed but.....

    I got it running good enough for now so what I've decided to do pending a compression test on all cylinders is to go with an all new valve train since I'm possitive the bottom end is sollid. Someting has to be off with that cam I checked the timing with and inductive light the mark on the crank at 800rpm with vac advace was pointing straight up and it runs smooth, without it at around 700 it was at ~16*BTDC on a 425 pully and marker

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    Re: 472 installed but.....

    well I did a compression test on 1,3,2,4,6 now 2,4,and 6 were at ~180psi but #1 was 0 absoultly 0 nothing didn't even move the needle and 3 was ~150 I don't understand how 1 could be 0 unless the valves where maby stuck open the rings on that piston couldn't be that bad I think I'll try a little oil in the cylinder and see if it does any thing if it doesn't that would mean valves right?

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    Re: 472 installed but.....

    well I tried the oil it did nothing so I'm thinking stuck rings? maby still a valve problem?

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    Re: 472 installed but.....

    burnt valve has to be I thought maby those rings were stuck from sitting so long but I sprayed a bunch of B12 chemtool and some sefoam deapcreap which are both supposed to be the best for freeing stuck rings but I looked down in the cylinder and those rings are sealing tight to the walls so I tried filling the cylinder with air and listening at the intake and exhaust and if I'm not mistaken I belive I have a burnt exhaust valve which would explain #1 being a dead cylinder right? so I'm gona remove the heads and take them to the local shop and most likely have new valves installed with hardend exhaust seats oh well even with 7 cylinders its still more powerfull than the 425.

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    Re: 472 installed but.....

    To be getting absolutely zero compression, I'd go past a burnt valve and say you have a bent or sticking valve. Heck, even without any rings at all it should still register something. You've got a cylinder that just isn't closing up.

    Good luck with the repair!

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    Re: 472 installed but.....

    thanks, I'm gonna try and get them off this week and down to the machine shop. I figured it had to be a valve because that B12 and stuff didn't even leak down past the rings so I know there good but to register 0 its like the valves aren't even there

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