: 472 heads on 500

08-25-04, 11:19 PM
just wondering what kind of heads a 71 deville would have on it if it came with a 472 and would they bolt right on my 74 eldo 500? also what would it do to the engine if i did this, what kind of flow and compression should i expect? and are the engine blocks the same?

also, would those 472 deville exhaust manifolds work on my 500 in the 76 seville?

Nick J

Allante North *
08-26-04, 08:08 AM
Hi Nick,

Your "71" Heads are 76cc and on top of your "74" 500 if it has 120cc heads will give you about 13:1. The exhaust manifolds will work. Check this link and it may answer some of your questions.



08-31-04, 12:06 AM
heres a few more ?'s

ok i bought the engine block, rotating assem., heads and exhaust manifolds off the 71 deville. i read somewhere that the true flat-tops make the comp. 13:1 and that the style pistons i should have should make 12:1 which sounds good to me. my question is will i have any piston to valve clearance issues without machine work, can i just bolt them right on? and will the rockers and such just bolt on off the 120 cc heads, cause i didnt get any with the 76cc heads.

im also assuming i have the 120 cc heads. i havent pulled the engine apart to see what it is. i noticed a 5A on them or something but thats all, i did notice the 5200 number though. it is a factory HEI engine which i was told meant that was a later model 74. is there a possibility that my engine was already a 76c head? im pretty positive its all original.

does anyone know which oil pan i should use? the 74 eldorado or the 71 deville?

and is there any difference between the 71 intake and 74?

thanks for your help guys

Nick J

barge master
09-01-04, 08:56 PM
Time for a reality check dude. If you put on those 76cc heads without strengthening the lower end you'll blow that thing to smitherines. Some cam and valve changes will get you some low dollar balls and it will still run on pump gas. Shitcan the stock intake for an Edelbrock too, it's worth the money. The stock ones are the worst design ever concieved of for performance. The DeVille pan has the front sump and is useless in anything but an old DeVille. The exhaust manifolds will bolt on, but they're a tight squeeze between the frame rails. MTS has a good website also and he knows the Caddy engine inside and out. 500cid.com. Good luck.

09-01-04, 09:48 PM
well i guess i could let you guys in on what im doing seems how nobody would be reading this unless they were building a cadillac themselves. im building this car for circle track racing not the street, i just didnt want to let anyone locally in on what was going on. i have to run stock everything by the rules, so although some choices may not be the best, i dont have any other option. anything aftermarket is against the rules. we must run a stock car minus interior with a stock engine. absolutely no race parts. i only plan on running race gas so thats not a big deal, i want compression. i cannot run the alum intake its against rules, as well as the headers and everything else you guys keep getting on me about. this has to be completely built on a budget, well because i dont have a big amount to spend. so basically i have to make the best of what cadillac gave me to work with from the 70's. no cam, no headers, no intake, no duals, no big olds (i doubt i can pull that one off in tech lane as easily) keep in mind most wont know as much about the cadillac as all of you, so a big 76ish 500 cadillac in a 76 cadillac chassis wont really mean that much to them.

i hope you understand better now, and hopefully you can continue to help me build one trick racecar.

barge master
09-03-04, 05:00 AM
Ahhhhh, Grasshopper you have enlightened us. I did that type of racing, esp. back in the late 80s. The track I used to love is no longer there though, they put a big stupid roller coaster in it's place. I ran a 73 CDV and it did pretty good in terms of power,it just didn't handle so well.I'll see what I can dig up for info for you.

09-03-04, 02:15 PM
the heads will swap right over ...... it is no big deal but you will be over 12 to 1 ..... the rockers will swap too they are all the same ... as for a intake all of the duel plane stock intakes are the same the only other stock intake to look at is the cast iron 425 cid single plane with the center cut out ...... if you run a qjet you will need to jet it up some ......the only other thing you can do is the cam ..... some of the stock timing chain sets put the cam in 6 degrees retarted ..... a stock replacement should fix it .....

09-05-04, 01:51 PM
thank you very much...i noticed the 71 intake doesnt have all the smog/egr junk on it that my 74 does so im gonna use the 71 unless that 425 intake would do better. im not really sure if it would help or not. ive read these engines dont like to turn a lot of rpms and thats really where a single plane should shine. anyone have any experience swapping these intakes and noticing any difference? and would the intake runners still be the same size?

09-05-04, 01:53 PM
....and the timing chain is a must for me, but i see theres a bunch of different kinds that very in price quite a bit, whats the difference?

lux hauler
09-05-04, 02:00 PM
You will lose a little on the bottom end with a single plane.....they work better in the mid to upper rpm range.
Cloyes makes a really nice roller timing set.

09-05-04, 04:41 PM
though single planes don't have a good rep for low end power it has a lot to do with the motor ....... below is a dyno run with a stock caddy motor and the bigest listed crane cam and the 425 single plane opened up in the center .... no port work everything else stock ..... power is at the rear wheels and peak is below tested rpm somewhere ...... also if you can find a copy feb 1991 stock car racing showed a dirt track caddy and the 425 intake is the one he liked ...... run would not upload but the link should work

ok link did not work either ........ run is posted at the coyboy forum ...... peak torque is below 2800 rpm ........don't know how low and that is with a big cam ........... for stock intakes with little work I think it is the best one

09-05-04, 10:32 PM
How serious do they get about checking whats in the engine ?
are you allowed to put in a replacement cam/pistons/valves ?
there is alot to be gained thru a new set of valves and a 3 angle valvejob
you could have a cam ground that would have basically the same lift specs as stock but that would make alot more power
as far as the intake goes the earlier duel plane might be your best bet and i know that some caddy carlo included have had decent results with a single plane i think the duel plane works better for what your doing.
I am not saying you should cheat but just take advantage of what you have

09-06-04, 12:13 AM
pretty much the most they check is for any physical differences that dont look stock and then they check for valve lift. they cannot check duration so that is unlimited but they do make sure stock lift is the same. they also would obviously look for any valvetrain parts that are not stock. i have to use some form of stock pieces. whether they are stock for 76 or not doesnt really matter, so i can run a 70 cam or something, all id really have to say is the motor must have been changed at some point in the car i got it from that is more than 30 yrs old. i dont really want to spend too much on it incase i do get banned for stuffing it between the framerails of a car that never came with it, but it does look like i should be able to run it because it is a 76 style motor in a 76 chassis. i cannot do any grinding on the intake but i can redo the heads and get a valve job done. where would i begin on getting a cam for it that would be better suited for what im doing, still having stock lift? also keep in mind i have to run an open rear end/single 2.5" exhaust and im running against a bunch of guys with stock/reworked 350 chevys so their power isnt all too high, and they are using the old cop-car caprices. id like to be able to leave the short block alone as it begins to get pricey the minute you take off the oil pan, and it ran great when i pulled the motor a couple weeks ago. but seems how the heads will be off i might as well have the new ones cleaned up, and the intakes off so i might as well put on the better one. if it sounds wicked though everyone will know im up to something. so ive got to keep the sleeper image.

lux hauler
09-06-04, 07:45 AM
where would i begin on getting a cam for it that would be better suited for what im doing, still having stock lift?
Torque Inc. (http://www.cadillachighperformance.com/) :D

09-06-04, 01:30 PM
you cant port the heads and intake but could you modify the plenum of the intake ?
by busting out the middle under the carb it will pick up quite a bit and will if bead blasted or shot blasted look like nothing.
If youd like i can send you a picture of one so you can do it yourself
walkerz @ zoominternet .net

forgive the spaces jus trying to avoid spam

there are a few other things but replace the cam bearings at least if it sat not running for any length of time

Mark --
09-07-04, 08:03 PM
I've done what your doing and am using the engine in a 1986 Chebby 4WD pulling truck. Have done a few less educated things.

If the oil pump comes off - make sure you get the thin paper gasket for it -- if not you may be putting grindings in your engine and have rod bearing problems.... (#8 to be exact) - {I bought a Fel-Pro engine set - it didn't have an oil pump gasket and I had a basket case engine to work with for the first time -- so I figured you didn't need one -- don't do that...}

I don't think the compression will hurt you as Caddycarlo runs that kinda compression + a blower + a little bottle -- Detonation will cause you problems -- I run 110 octane racing fuel and limit the timing to around 34 degrees @ 3,000 rpm.

go to 500cid.com - Al has some good parts and an online catalog (he's got the oil pump gaskets seperatly as well)

He also has a 1 or 2 in spacer that goes under the Carb. It gets the back throttle plates out of the manifold - frees it up quite a bit. Painted I doubt they would even know or notice.

They only check to see that we pull 15" Vac. I'm running Al's VT-15 cam and it's on the edge. Down from that is the 3 - 5 and 10 series. They are ground to upgrade the design from orginal and retain drivablity. The 3 - 5 and even the 10 do it without a lope. I think the highest you could go without upgrading valve spring and cutting down the length of the valve guides is the 5 and maybe even the 10.

You could also upgrade your HEI with better pickup, coil etc.

After the three engines I went through in the last three months - I glad I properly cleaned the block, had new cam bearings and had the rod journals turned 20 thousands instead of tailgating the engines together.

Even though your engine ran good - how long has it sat around - old acidic oil does a # on bearings. Then you add near 13:1 compression :crying2:

Doing what I recently did - I would consider just a minimum.

Your experience may differ - I think my oil pump problem carried with me throughout the first two engines. (I just wasn't about to chance things again)

Let me know how it turns out - I only have a 15 second run - your's will be endurance

Mark -- :welcome:

09-07-04, 08:53 PM
all of your help is much appreciated...

just wondering if anyone knew, or knew where i could find the stock specs of all the cams that the 500/472 came with. im having the hardest time finding them on all the sites you guys have directed me to, maybe im blind? and is the ones offered in summit/jegs any good? if this was a small block chevy id have no problems but this caddy stuff is a whole different beast.

maybe i should start another thread for this one but you guys seem to know a lot, so i was wondering do i have to run the gigantic flywheel that came on the 74 eldo 500 or can i use the smaller one off the 71 deville 472? and has anyone ever used a th350 behind one of these motors? i was planning on using the stock 3 speed still in the 76 deville behind the factory 350 olds, due to less rotating mass than a th400 and i was planning on running a stall convertor maybe as well but dont want to run a 13" converter, or whatever that eldo had in it. keep in mind this is for momentum kinda racing not hard launches like drag racing so i think the tranny should be able to hold up.

and i dont think i can run a carb spacer unless theres some kind of invisible spray paint that will make it un-noticable when they lift the hood, everyone knows what they look like so it will be spotted the first time i get teched.

i guess the biggest thing that makes me want to avoid rebuilding it is the cost of a rebuild kit. its 4 times what i paid for the motor. and i dont know if i could get that back out of it if i had to sell this motor on the street beacuse they found it to be illegal.

Mark --
09-08-04, 08:29 PM

Just thinking of a couple of other things.

By doing a valve job on the head you have and milling say 20 thousands - you'll bump your compression a little and be pretty reliable using 93 octane.

I've also heard to use your stock cam and advance it about 4 degrees will help quite a bit. You've already got alot more that those Chebbies - remember that

If you go to the high compression route - you might consider hooking up an additional ignition switch - say - under the dash. Your starter will have enough to do with that 13:1... When you add that to a hot motor and around 10 degrees initial advance - it will be hard to start when warm.

This way you can crank the engine over and then hit the Ign when it's whoopin good. --- Saves that buckin against the initial advance!! :bouncy:

Just thinkin outloud

Mark --

09-24-04, 10:24 PM
Hey TorqueInc!!! Just saw that you recommend grinding the center out on the intake of that 500 Caddy engine someones building for a racecar...I'd like to see a pic of just what you mean. My hot rod project is my '60 Dodge D-100 w/ a 413 HP from a '62 car. Slowly coming along, but its on hold now, as I'm putting a new motor in my 94 Seville STS...And I've got a '72 Eldo that I picked up for super cheap and I'll probably never get around to working on...but I would like to know more about this intake work you talk about. Thanks a bunch! my email is spyder121212 @ hot mail.com


10-09-11, 05:30 PM
MTS,can someone give me the web address for mts

10-09-11, 10:10 PM
Just Google MTS cadillac