1970-472 rebuild "with benefits"

["Cadillac Kid" Greg Surfas 15364]

Alright, I have FINALLY gotten the cylinder heads back from the machine shop. Their "two week"job turned out to take one year. since I had no immediate use for them it really did not matter, and the results were well worth waiting for.
With that in mind I will continue this discussion

]One of the positive things I have been able to due during this "slowdown" is put together a 472 motor.  The motor itself had 103K miles an on tear down there was less than 0.001" wear in the cylinders. Crank was also pristine and everything else checked out pretty good.  My thought was to "Blueprint" the motor and add just a few things to improve the low speed (to 4800 RPM) power without going exotic.; The motor will retain a stock idle and will maintain stock rocker system.
Here are a couple of shots of the short block.  The heads are at the machine shop for valves and porting and that info will follow as soon as I have it.
Block info includes zero deck, moly rings standard bearings (rod, mains and cam.
The top picture is as I was pulling the motor apart, and the bottom two are as machined and reassembled

["Cadillac Kid" Greg Surfas 15364]

 First let me qualify my methodology.  I am using a relatively sophisticated computer simulation program that I have verified with real life numbers to be within about 4-1/2% of dead on.  I have a lot of confidence in the results.  As an example, I "built" a stock motor (in the computer) used those figures an input for ¼ mile times.  The computer said 16.4 seconds.  The ACTUAL repeatable times were 16.39. That is within 1%.  As I modified my motor and car and using the new values as the computer input the actual track times fell right into place.

Let's start with a stock 472. 4.300 inch bore, 4.060 inch stroke. "binocular" shaped valve reliefs in the top of the piston, standard deck clearance and all original components. Actual compression ratio works out to 9.71.   NET HP at 4500 RPM works out to a REAL 226. (sorry that's really it).  Net torque is 310 Lb/Ft at 3500 RPM.
While the heads get freshened up and "slightly" shaved so our resulting compression ratio ends up at 10.39.  Now you might say that is a bit much, but we are going to use a stock 1973 cam with lightly longer duration and a bit more overlap that will tame that compression a bit so we can run 93 octane unleaded pump gas and a normal advance curve.
On this motor I've actually done a bit of port work which although it is not in the calculations will add a good 5-7-1/2% to flow specs and power.

Now, let's see exactly what we have out there.  Horsepower and torque numbers have varied according to standards used and "poetic license".

By just these few changes we have upped the performance substantially.  NET HP jumps to 266 at 4000 RPM with a boost in torque to 444 Lb/Ft at 2100 RPM.  Note both HP and torque curves have shifted to the left (lower speed) which for a stock geared Cadillac is quite beneficial.  The cam used in 1973 was intended to raise the torque on the 8:1 motors which it did.  Unfortunately on the low compression motors the idle quality suffered slightly if the emission controls and a slight "out of exact tune" combined, so customer satisfaction resulted in going back to the older cam profile back to the older cam profile.

["Cadillac Kid" Greg Surfas 15364]

The first screen shot is of the stone stock motor
The second is with the 9.85 compression and the Cad Co cam
The third is with the ported heads added.
Numerical results for this motor are 456 Lb/ft of torque at 2000 RPM that will pull tree stumps and 320 HP at 4500 RPM. Well above the performance shown by the stock motor.
I hope all that was informative and did not put anyone to sleep. I'm going to take a couple of shots of the heads to show the porting and post them.
Greg Surfas

["Cadillac Kid" Greg Surfas 15364]

Here are a couple of shots of the heads. About a 24% flow improvement

[Roger Zimmermann]

Impressive...Come to me and do the same to my '72 engine! I'm sure it would be a different car after this mild treatment!

[James Landi]

Greg,

Your "minor improvements" create some dramatic results. Any speculations as to why the engines were not designed that way at the outset?  Having owned a couple of these big block Cadillacs during my "younger days," I discovered I could do substantial damage to motor mounts and flex plates on these cars... my thinking is that the drive train and associated parts were not sufficiently robust to handle full throttle starts.   James

["Cadillac Kid" Greg Surfas 15364]

James,
I don't think it had anything to do with the drive trains. Unless you severely abuse them they are essentially "bullet proof".
The 472 then the 500 series was built with a lot of untapped power, and I believe that had not the Mileage/[pollution gremlins hit, they would have been tapped. As far as the cylinder head work is concerned all this as done on my heads is hand work and quite costly. The state of the art in macining like CNC was still just on the horizon. Currently CNC is used for just about all machining tasks and as you know engine outputs today per displacement are what only all out racing motors were putting out in the 70's.
I have a set of CNC cylinder heads on my quarter mile car and the flow ratings are even (about 40%) better than the heads on this motor. HOWEVER they are still costly.
Greg Surfas

["Cadillac Kid" Greg Surfas 15364]

Roger
Bring the car here (quite a. Boat ride) and we'll put the motor in it
Greg Surfas

[Roger Zimmermann]

Roger
Ring the car here (quite a. Boat ride) and we'll put the motor in it
Greg Surfas

Thanks Greg, but for the 1000 miles per year I'm driving, I think I have less stress letting it the way it is!

["Cadillac Kid" Greg Surfas 15364]

Then look at it this way Roger.  At the rate these motors wear out that would give you better than another 200 years of cruising the Alps.
Greg Surfas

["Cadillac Kid" Greg Surfas 15364]

bump

[chrisntam]

Why the BTT?  Have you some exciting news?  Time slips?  Dyno results? Video (and audio) of a nice, lumpy idle?

["Cadillac Kid" Greg Surfas 15364]

Chris,
The motor is still on the stand, and there will be no loping idle. Just an honest 100 HP over stock. I don't have anything to put the motor in other than possibly my "Paris", but I am going to add a bit more to the thread and I just wanted it to be somewhere I could find it again.
Greg Surfas

[Roger Zimmermann]

....but I am going to add a bit more to the thread and I just wanted it to be somewhere I could find it again.
Greg Surfas

I understand you! After a while, you'll have to search into about 10 pages to find your topic. And, if you don't remember exactly the title of the subject, the search possibility is more a miss than a hit.

[James Landi]

Agreed... I really enjoy the forum, and would love to see a section such as "sticky posts."  Some of the questions that come up  are gremlins that plagued certain models and model years, some a elegant work arounds,  and a few, like Greg's are engineering break throughs that deserve a wide audience.  James

[Cadman-iac]

  Greg, I have a question or two for you. You mentioned that the compression ratio works out to be 9.7 to 1, yet the factory has always listed it as 10.5 to 1. Were they cheating, or is there some other way to calculate the ratio that they used to get the numbers they advertised?
If I remember correctly, the 70 was 375 hp and 525ftlb of torque for the 472, or something close to this.
You said you would have 226hp and 310ftlb of torque. Is this also because the compression ratio is not as advertised? Or their numbers were at the flywheel, while you're going by what reaches the rear wheels? That would explain the hp and torque ratings, but the compression ratio is a different story.
  Very interesting information on these engines. Thanks for sharing your knowledge with us.

Rick

[35-709]

Not to speak for Greg but if you read the first few of his posts in this thread you will see this is a detailed, "blueprinted" engine, with modified heads, etc.  Would be fun to drive his Paris or whatever that engine goes into just to feel the power.

["Cadillac Kid" Greg Surfas 15364]

For "advertising" purposes, the compression ratio on the 68 and 69-472 motors was listed as 10.5:1 which, as practical experience showed (what ever the real CR was) resulted in motors running a bit too hot. For 1970 they revised the pistons, and a compression ratio of 10:1 was listed.  When you actually "CC" the pistons and the 76 cc heads the static compression of the 1970 -472 is 9.75:1.
The "advertised HP was just that and for sake of Cadillac's honor we will call it "gross" HP.  The Net HP was about 225.
You will note in 1971 when they lowered the compression, they advertised the HP at 3875, and in 1972 with exactly the same motor as the 71 the HP dropped HP to 220.  That was net HP. the drop in compression ratio from 9.7 to 8.5: resulted in an actual loss of less than 10 hp.
Greg Surfas

["Cadillac Kid" Greg Surfas 15364]

Geoff,
When I got the Paris (1979 CdV) it had a carbureted 425. It by itself was a great motor and I had trouble keeping the tires quiet at stop signs. On its way out the transmission took the crankshaft thrust bearing along for company, so I replaced it with was essentially a 1974 -472. It was a .030 over flat top piston with 120 cc heads (large chamber). You know me so I talked to Marty at MTS (obviously a while back) and they ground me what he called his #5 cam.  Idles just like the stock 425 and is quite throttle responsive/. If I want to go faster I have the 73.
Greg Surfas

[Cadman-iac]

  Yes, I did see the earlier post, and he mentioned that on a stock motor, the ratio is actually only 9.7:1, but after the modifications it worked out to 10.39:1.
I'm curious to know why the factory had misrepresented the compression ratio, if he has any thoughts on it anyway.
Seems like they cheated on the figures to gain bragging rights or something.

Reread his post to see if I'm mistaken. It wouldn't be the first time, but I think I read it correctly.

Rick

Edit: sorry Greg, you posted twice as I was checking my facts for this post.