What would you get - can it be done: 425 block with a 472 crank

bugzaper

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Brain storming.
Wondering what would you get by combining the two.
Seems like the weight savings would be good.
Heads might be too restrictive.
Would it be worth it.
Can it be done.
Can't seem to find any info. in here on the combination.

>425 block
>472 crank

What: rods
What: pistons
What: bearings
What: machine work would be needed

Or.

Maybe go the other direction.

>425 crank
>472 block

"Hmm"...
 

Cad Man

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Yes it can .. a much improved 425

425 block
472 crank..
472/500 main caps
472/500 rods or better

For that matter a 500 crank may should fit esp if the bottom of cylinders are notched

4.082x4.304 = 450
4.102x4.304 = 455
4.112x4.304 = 457
 
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Monzallac 425

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425 block is weaker and less weight, cranks are lighter than 472 stuff I believe.

Don't know about mixing up stuff between the 3, definitely need more oil pressure for the 425 to survive any beating.

Arguments about 425 crank- block flex have been covered on here before.

Doug in P.R.:)
 

kzhurley

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Interesting info....

I've always wondered what a 425 would do with pair of 472/500 closed chamb heads..
 

Cad Man

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I have 70 psi plus in my 425 and it held up to a shit load of 5500 shifts..a few 5700 and several 6000 accidental shifts..
I put 12,000 on it while building the 507

When I changed cams and intake I also put a modified 7qt pan on and while the pan was off since I didn't buy the car new and it had 42,000 miles on it I swapped in new rod and mains .. everything looked almost new. I posted pics of the worst looking bearings which hardly had any wear... I did not disassemble the motor fully. left the pistons in and snuck the crank out to do it..

I have my custom super modified Caddy pump on it and in fact had 80 psi at 200 degree oil temp and 27 at 800 idle. I took out some shims to back it down a bit to 70

The head swap would need some looking into as the steam holes are different. The 425 exhaust manifolds are HORRIBLE. headers or older manifolds will make a huge difference. It dosent even sound the same when you change them

The 425 and 120cc heads flow about the same. Only a few cfm difference.
With mt10 2115 intake 950 Holley and headers I would guess it made about 390 hp.

I made 1/4 pass in the 79 CDV at 4600 pounds plus me... It was blowing the tires off and still ran 14.8.... But @ 98 mph. That's mid 13 seconds pass mph

Caddy rear end 3.23 Eaton posi..
th400 2400 stall.
 
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kzhurley

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More good info Cadman...

I have no need to do the 425 head swap as I have 5) 500s laying around..lol

Just a more of a curiosity and around here if you find a 425 for sale they are almost free...
 

Cad Man

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I had fun with it.. I've had a few of then and they have been good.. alot depends on what the clown that had it before you did to it as is true with any 50 year old engine.. a few overheating it till it stalls episodes or extended overheating weakens everything.

Let's face it with the luxo branding and the stereotype of the people that drove them it happened alot. Even if they paid attention to the dummy lights by the time they lit up its game over

If you changed main caps and put a 472 or 500 crank in it would be much better at handling alot more power.

I think the main caps and rods need to go if your trying to build serious power ..
 
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bugzaper

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"450" I like that, which is more than a (other corporate...) "454" with less weight!
Bonus here is I already have a few "425s" and several "472s" stuffed away.
Tired of searching for a "Good" used "500" crank.
I may take the challenge and build one this winter.
 

Cad Man

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Here is a unrelated tidbit

The 2000 hp slat flat motor that sucked a valve was actually a 484..

Yep 484

472 destroked -.120. Bored .120

3.942
 

bugzaper

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Taking the stock bore "425" block to the machine shop tomorrow along with a set of "472" rods - crank - good used "472" pistons.

Going to see what can be done.
Trying to build with what I already have to keep costs down.
Have a cast iron ported manifold I ported several years ago and will be using it along with a set of stock cast iron "472" exhaust manifolds.
Already have a brand new stock spec. cam - timing cover - chrome taller valve covers - water pump - Eldorado pan & pickup- flywheel eca. eca..
Thinking the biggest cost with this build will be the machine work and maybe a valve train upgrade (not sure about that yet).
Not trying to build anything wild just a good solid low rpm everyday torque engine!
 

Cad Man

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You cannot use 472 pistons.
4.300 bore the 425 is 4.082

Dont use that cam. .. get something better. It will defeat the purpose of the other stuff your doing..

For really good low end mid and something left over 4000 Get something 220 ish @.05 and 106 lsa.. .550 lift

Have it ground 4 degrees advanced ..
And install it in the advanced position for 8 total under rpm it will retard to 6ish and be perfect..

It will blow your mind with low end too

I can give you lobe numbers for Howard's and you can have it made. Much much much better than anything off the shelf too.. Howard's is really good to deal with .. Lunati not so much

I ran a mt10 in my 425 ..
it is 225@.05 .544 lift.. 113 lsa ..

despite the lame lsa it still had good low end ..

Have you seen the video I posted?

 
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bugzaper

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"Thanks", most likely will go to a flat top piston, O-deck the block, shave the heads, it is what I did with my last "425" and have never had any issues so far "15" years a counting.
I like the "MTS" cams, used LUNATI in many past builds but, as you stated they just aren't the same any more.
Need to track down a good used "Points Dist." as I'm going to convert it over using an "HEI" module.
And, not quite sure about what carb., thinking an Edelbrock 750cfm, maybe another "Q-Jet."
Just trying to keep the build "Low Buck" as much as possible.
 

Cad Man

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Thought he got pissed off and left this forum....:confused:

He must of overdosed on chill pills.:sick:

Glad to have him back then , a wealth of Cadillac knowledge he has.:thumbup:

Doug in P.R.:cool:
What who where when why wonder nope I didnt dood it I didn't know I swear it wasn't him or me or you I dont know anything honest abe junior
 
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