I need a little help in making a decision, I currently have a 1968 472 sitting in the garage however it needs a pair of cylinder heads (along with a complete rebuild) now I found a local yard with a few old caddys in it and I can get a pair of heads from a 1968 or a 1969 for a $100 if I pullem' however the owner of the place has a pair of heads sitting on a shelf he'll sell me for the same price but there deffinently not the 76cc heads the 68 came with they have a large round chamber I think they're the 120cc heads and they don't have the AIR RAIL either. which I don't want the bigger 120cc heads and endup with 7:1 compression He also has a 500 complete from carb to fan to compressor IIRC it had the HEI but I'm not 100% on that but it definently was the same color blue as the 425. He said he'd sell it to me for $400 and that it was a good running motor when removed from an eldorado. now I'm not sure on the year of this 500 if it was the 1970 I would have bought it on the spot but I noticed the HP TRQ drop big time after 71. So heres the question sould I get the 500 even though it could be from the mid 70 low compression engines lower HP TRW motors fresh it up a little and drop it in my 77SDV or should I stick to spending aroud $800+ in rebuilding the 472 I have? a plus to doing the 500 is I could sell the 472 + the 500's carb, intake, dist, and other general accessories and gain back some cash any help is much appreciated thanks P.S. sorry for the long rambled post

Well I went back out there today and tried to pull the heads off a 472 which turned out to be a nightmare so I stopped and checked out the 500 it does have the HEI and the guy said he thought it came out of a 76 eldorado. now what I need to know is the 76 500 a good motor by good I mean better than the 425 in my 77 as far as power goes. I can still get the heads for the 472 its just gona cost 200 to have the guys there remove them

They're all the same after a good rebuild. Don't pay attention to the power ratings because they are different (the ratings changed from net to gross or gross to net or whatever, which means the earlier engines weren't making all that much more power than the later ones). Also, emissions had a lot to do with the power ratings. If that engine is out of a '76 it will have 8:1 compression with 120cc heads. 76cc heads on it will make 13:1, keeping the 120cc's on and getting flat top pistons will make 9:1, or getting 76cc heads and big dish pistons will give you about 10:1.

I remember reading about that gross to net ratting change but I was looking through my Chiltons repair manual it list all the general engine specs for 67-89 it says the Hp ratings are all SAE net figures which are measured at the rear of the transmission with all accessories installed and operating it still list the 68 & 69 472's as having 375HP@4400rpm 525FTlbs@3000rpm and the 76 500 as having 190HP@3600 and 360FTlbs@2000RPM. I think I'll just see how much he'll sell me one of the 68 472's and just do refresh with a little valve train work on it since I already have some parts stored up from the 472 I've got then just sell the 472 block and crank I have in the garage to regain a little $. I'm not to sure on this chiltons engine spec sheet because it list the 77 425 as 180HP@3600rpm with 260FTlbs@2000rpm but the 79 425 is at 180HP@4000RPM with 320FTlbs@2000rpm compression is also diffrent in 77 it says it is 8.5:1 but 79 goes to 8.2:1 any one notice that :confused:

Someone else chime in and back me up on the power ratings. Chiltons don't got nothin' on me!!! :)

Chiltons/Haynes are junk... don't even waste time or money.

The "big loss" in power was the SAE/NET HP ratings... in reality its only a 30-40hp difference form a 1970 500 to 1976 500.... that difference is form a drop in compression and all the extra emmissions....

also, HEI is far superior to the older point style distrubutor... and it would get swaped over.

It's approx. a 20hp difference due to compression only. A hell of a lot more, probably more than 40hp, due to the wack ass beaded cat used on 75+ (maybe 74 as well) 500s.

what years came with the 500>

70-76 Eldo, 75-76 all Cadillacs (excluding 76 Seville.)

Well Friday I went out and paid for a 472 and the guy said it should be ready monday now from what I could tell from the car it's a low mile motor the oil must have just been changed prior to being stored up because it was perfectly clean the transmission fluid was clean with no burnt smell the odometer was around 47k the seats showed no wear from use and it still had the old AC R44N acniter spark plugs which look good. So my plans are to remove the heads which are the 950 castings have them cleaned and checked install all new gaskets, New lifters, timing chain, HEI distributor, rebuild the oil pump, a new or rebuilt water pump, my current almost new fuel pump with recently rebuilt carb, and new brass freeze plugs, plus oil pan and pick up from either my current 425 or I was wondering if one from a 81 368 would work anybody know? I'm not to sure if I want to replace the cam just yet after all the engine makes more than enough power for me (at least for now) all this should be taking place with in the next 4 or 5 weeks or less can anyone think of anything I forgot also I have a 472 block, crank, rods, pistons, manifold, timing cover plus some other accessories for sale if anyone's interested one more ? how much worse is the 472 on gas what are the typical #'s just regular driving not that it matters just curious

well I got her home today she's deffinently a low mile motor the water neck had no rust inside nor did the water pump both looked brand new (on the inside anyway) the rocker arms are very clean but I did find out what probably led to the car ending up at a junkyard one of the push rods is bent bad (pics soon) and another one was twisted looking at the top but the lifters show no wear or damage and as far as I can tell at this point that is all that caused its life to end short. Tomorrow I'll pull the heads and have a look in the cylinders the engine still retains much of its original blue paint under the dirt:bouncy:

Here's some pics the day I got it home and of the bent pushrod.

and heres what she currently looks like after about a little more than a weeks work, new brass freeze plugs, a good cleaning and many layers of gloss black paint, and a new timing chain the old one still had the nylon teath around it sometime this week should be getting the liffters in then this weekend gaskets & push rods

man, that looks good, ur making me want to pull mine out!!!!

Nice project!!!!

Thank you, this is what she looks like now with the cleaned and reasembled cylinder heads now all I need is to paint that manifold and a few other things and she'll be ready to drop in.