News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

differences in 500 CID engines

Started by Brian Rachlin, April 29, 2005, 11:49:32 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Brian Rachlin

I have a 1976 Eldorado.  I also have a 1985 Eldorado Convertible with the HT4100 in it, running fine.  These engines dont last forever, and eventually I will do a swap.  I have read, on the HT4100 message board, that you need some 368 parts, mainly brackets to bolt a 368/472/500 into the engine bay of a 1985 Eldo.

I figure if you are going to do a swap, why do a 368 if a 500 will fit...

This leads to the main question...What is the difference between a 1970 500 (highest HP of all the 500s) and any other 500, like the one in my 1976 Eldo.  Is it the heads? Cam? Pistons? or all of the above?

I want to start getting some parts together, but I dont plan on doing this for a while.  If the block will bolt to the bell housing, and there is a flex plate that will work, I think a 500 CID motor in a 1985 Eldo would be pretty slick.

I do realize that if you really pound the thing that the trans will not hold up, but I would be willing to give it a shot...

Thanks,

Brian

Michael Stamps 19507

Hi Brian,
  Welcome to the Proposed Modified Cadillac Chapter world.  I give you kudos on your last sentence so we will pass over that major problem.  The 472/500/425/368 engines are divided by early and late engines first.  The 472 and 500 are early with the 425 and 368 being late.  
  Since we want the most power lets look at the 472s and 500s.  You asked about the 70 Eldorado engine and the others.  Well the 70 Eldorado has the 76cc heads for higher compression and is the first year of the 500.  Thats all that makes it special.  If you are looking to rebuild the engine you can do better than factory with not a lot of effort.
  For example I am building a 514 (.060 over 500) engine for my 70 Deville.  I have a 76 500 engine core and my 70 76cc heads to put on it.  Since I am rebuilding it I can use pistons for an early 500 engine in my 76 block with my 70 heads get around 10.2 CR.  I am also using olds 425 rods as I plan on hitting 600hp and high rpms later on in my build.  Factory 500 rods will be fine below those limits.
  If you want a drop in stock engine all of the 472/500 engines with the right tune will give you around 300hp and 500 ft/lbs of torque out of the box.
  The early high compression heads will require higher octane gas and if going for more of a high performance build they will make it easier.  The later low compression heads will allow you to use regular gas but wont get you to the 500hp levels as easy.
  Sorry for the rambling but if you wish to continue with this crazy idea let me know.  Its no where as bad as the project Im doing with my friend of putting a 70 472 into a Datsun 260z.

Stampie

PS - Visit the other head cases at http://www.modifiedcadillac.org TARGET=_blank>www.modifiedcadillac.org .

Mike #19861



 As an annendum to what Stamie said, the 500 from 71 and 72 would be a good fit for your requirements. The power is down a bit from the high compression 500s of 1970, but they still manage considerable power from their 8.5:1 compression ratios.

 These engines will also survive and prosper on lower octane fuels that are cheaper and more redily availble.

 But, the transmission will have a tough time of it. The torque from any 500 will simply destroy any 200 4R unless driven very cautiously. There are upgrades that can be made to the transmission such as Grand National clutch packs and forged input housings. This can make the transmission live, but is an expensive upgrade.

 A 500 in an 85 Eldorado would be a thrilling ride, to say the least. Maybe one day I will do this as well. But Id still like to put a relatively warm 500 in a boxy Caprice Cop Car and go out and spank some so-called fast cars!

  Mike

Brian Rachlin

Is there another trans that will work?

Brian

Michael Stamps 19507

The 425 will but you would be looking at a lot of custom fab work to get it in there.

Stampie

Mike #19861


As Stampie says, the THM425 will take the torque, but it is much larger than the THM200 4R that is in there. Much adapting a fab work will be required.

 You may be better off to just have the one done over in the car so that it will stand up to the 500. But even then, you may have to go easy on it. But it should still allow for some sprited driving.

 Another possibility is to have a 325 built up. They share most of the internals with the THM350 and there are many upgrades available. But they are a 3-speed deal without lockup. They were used in the 1979-1980 E-body cars so it should be a bolt in.

  Mike

Ken

Car Craft just did a write up a couple of months ago about bulletproofing a TH 200 R4. Probably the best route to take, as it will keep the modifications to a minimum.

Ken

Michael Stamps 19507

Bulletproof behind a Chevy but a 500 putting out anything other than stock will tear these up.  You are also looking at a lot of money to get them there.

Stampie

Ken

They had built up the 200 R4 for drag racing use, I believe it was rated to 800 HP.

Michael Stamps 19507

Its not the HP that kills them its the torque.  A Cadillac 500 with 600 ft/lbs is like a Chevy small block pushing out 800 hp.  I consider that a mild Cadillac 500.

Stampie

Ken

It was the April 2005 Car Craft. California Performance Transmission was the shop. They didnt have a torque rating, but assuming 800 HP at 6000 rpm gives 700 lb/ft
(T = HP * 5252 / RPM)


http://www.cpttransmission.com/ TARGET=_blank>http://www.cpttransmission.com/