Only because a few here are interested...

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HotWheelsBurban

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Congrats on the sale!
I need to go pull the heads off that 77 Eldo at the yard(I'm not sure what condition the ones are in, that go with my engine) Would like to get the whole engine, but I gotta have a truck to carry it in, and a way to get it outta the truck and into the building,and a place for it once it's inside. And of course the $$ for it in the first place!
 

Erik the Awful

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Would a 77 eldorado be a 500 or a 425? And are the heads the same? I know where one is that still has the motor in it,transaxle too I think.
It's a 425. Similar block, but a smaller bore, and you can't bore it out to a 472/500. The 472/500 bore is 4.300 while the 425 is 4.082 - almost 1/4" difference. Note that the only difference between a 472 and a 500 is the crankshaft stroke, 4.060 vs 4.304. You can put a 500 crank in a 472 to make a 500. the 425 shares the 472's 4.060 stroke. The one significant difference is that the 425 is about a hundred pounds lighter than a 472. I don't believe you can put a 500 crank in a 425 block, but I wouldn't mind trying to find out - that would be a 451cid motor.

Let's see if I can remember this right...
Early motors ('68-71) have dished pistons and small chambers in the heads. Factory 10.5:1 compression ratio.
Later motors ('71-76) have flat top pistons and large chambers in the heads. Factory 8.5:1 compression ratio.
425s had mild dishes and medium chambers in the heads. Factory 9:1ish compression ratio. I think they need porting to match the flow of the larger heads.

If you have a later motor, putting the early heads on gives you 12:1 compression. Putting 425 heads on gives you around 9.5:1 compression.
If you have an early motor, putting later heads on gives you 7:1 compression.
The later heads typically have a smog port running through the head, which makes a bump that runs from one end of the head to the other right under the rocker arms. they're pretty easy to identify.

 

1ton-o-fun

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It's a 425. Similar block, but a smaller bore, and you can't bore it out to a 472/500. The 472/500 bore is 4.300 while the 425 is 4.082 - almost 1/4" difference. Note that the only difference between a 472 and a 500 is the crankshaft stroke, 4.060 vs 4.304. You can put a 500 crank in a 472 to make a 500. the 425 shares the 472's 4.060 stroke. The one significant difference is that the 425 is about a hundred pounds lighter than a 472. I don't believe you can put a 500 crank in a 425 block, but I wouldn't mind trying to find out - that would be a 451cid motor.

Let's see if I can remember this right...
Early motors ('68-71) have dished pistons and small chambers in the heads. Factory 10.5:1 compression ratio.
Later motors ('71-76) have flat top pistons and large chambers in the heads. Factory 8.5:1 compression ratio.
425s had mild dishes and medium chambers in the heads. Factory 9:1ish compression ratio. I think they need porting to match the flow of the larger heads.

If you have a later motor, putting the early heads on gives you 12:1 compression. Putting 425 heads on gives you around 9.5:1 compression.
If you have an early motor, putting later heads on gives you 7:1 compression.
The later heads typically have a smog port running through the head, which makes a bump that runs from one end of the head to the other right under the rocker arms. they're pretty easy to identify.

I know what you meant... but for those that don't...
Flat ('er. Actually a peanut shaped recess) pistons in the early engines and a much bigger, deeper dish in the later engines. Mine was a '75.
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HotWheelsBurban

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I know what you meant... but for those that don't...
Flat ('er. Actually a peanut shaped recess) pistons in the early engines and a much bigger, deeper dish in the later engines. Mine was a '75.
You must be registered for see images attach
That looks like what mine is. Supposed to be a '74. What the guy would do, and he did this for several years, is buy a new half ton 454 square body Burb, and yank the running gear out and sell it. Then the previous year Cadillac running gear went in the Burb. Not just engine and trans, but rear end and drive shaft too. He ran a Cadillac garage ( they serviced all makes but specialized in Cadillac) in Houston,had a lot of River Oaks, Tanglewood, West U, Bellaire trade. It'd be interesting to know if any of these Burbs are still around; ours got hit by a tree, a week after we sold it(minus engine and transmission, why I still have em).
Thanks very much for the information and wiki link!
 

HotWheelsBurban

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It's a 425. Similar block, but a smaller bore, and you can't bore it out to a 472/500. The 472/500 bore is 4.300 while the 425 is 4.082 - almost 1/4" difference. Note that the only difference between a 472 and a 500 is the crankshaft stroke, 4.060 vs 4.304. You can put a 500 crank in a 472 to make a 500. the 425 shares the 472's 4.060 stroke. The one significant difference is that the 425 is about a hundred pounds lighter than a 472. I don't believe you can put a 500 crank in a 425 block, but I wouldn't mind trying to find out - that would be a 451cid motor.

Let's see if I can remember this right...
Early motors ('68-71) have dished pistons and small chambers in the heads. Factory 10.5:1 compression ratio.
Later motors ('71-76) have flat top pistons and large chambers in the heads. Factory 8.5:1 compression ratio.
425s had mild dishes and medium chambers in the heads. Factory 9:1ish compression ratio. I think they need porting to match the flow of the larger heads.

If you have a later motor, putting the early heads on gives you 12:1 compression. Putting 425 heads on gives you around 9.5:1 compression.
If you have an early motor, putting later heads on gives you 7:1 compression.
The later heads typically have a smog port running through the head, which makes a bump that runs from one end of the head to the other right under the rocker arms. they're pretty easy to identify.

I have the 500 crankshaft, but not the pistons (Dad probably wasn't buying those till we had the machine work done so he'd know what oversize to buy). Back then we were still in the parts business,so anything we needed was a phone call away.
 

Erik the Awful

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I know what you meant... but for those that don't...
Flat ('er. Actually a peanut shaped recess) pistons in the early engines and a much bigger, deeper dish in the later engines. Mine was a '75.
Doh! I have an early 472 and a late 500, but I haven't had the heads off either in years. I was thinking the earlier motors had the big dishes.
 

1ton-o-fun

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The '70s weren't nice to performance. The early 500s had higher compression and other subtle things that helped produce more power. Mid '70s were laughable (look at the anemic Corvette. America's flagship sports car).
At least gas powered Cadillacs ended with a bang! The I'd love to own one of the last performance gas powered Cadillac they made!
 

1ton-o-fun

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A little longer than mine ;)

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Maybe a little, lol!
I'm surprised that the lengthy Caddy output shafts weren't prone to breaking. Especially with all that torque. I guess the buyers of those big Cads were much more mentally mature than me (not that the bar is set very high there!).
 

stutaeng

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There's adapters to convert from the BOP to Chevrolet bell housing. I believe all of the BOP were considered heavy duty cases. They make good candidates for doing a track TH400.

You'd cut the bell housing for SFI Bell housing anyways. And swap to the short output shaft...
 
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