1976 500 to 1970 eldorado engine swap

Started by 2001stanley/khoe@mum.edu, July 27, 2008, 12:53:50 PM

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Is installing a 1976 500 into a 1970 Eldorado a pretty much done deal?  Or is there some modification necessary?
Thanks,  Stan

TJ Hopland

Should be no problem.  Differences are for the most part bolt on.  One catch is I think in 70 one heater hose came off the front of the block instead of back of the head like the later ones did. Some blocks wont have the hole.  76 had a few extra holes for extra emissions stuff.   

What happened to the 70 motor?  In from the factory stock form the 70's had the most power. Every year after that they lost power due to emissions.  Later motors can be built to have the same power.  People looking for insane power pay big bucks for the 70 crank and heads because they can be more modified and take more abuse than other years.   For fairly stock street type applications any of them will do fine.  Big differences are the heads.  68-73 were small chamber which gives high compression with fairly typical pistons.  In 71 to meet GMs mandate for low compression they dished the heck out of the pistons.   By 74 they gave up and designed new heads that gave low compression with typical pistons.   Other than that the rest is in things like cams.   The 76 would have different front pulley arrangement to clear the HEI and may or may not have a smog pump depending on where it was sold. As long as you have both motors you should be able to swap things around to make everything work.  Exhaust manifolds and oil pan was different between the Eldo's and the RWD cars. IF your 76 motor was a RWD you will also have to move the dipstick which can be a big pain.  Passenger side exhaust was different depending on emissions.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason


Thanks for the tips.  the '70 broke a rod bolt and cracked the block pretty bad

Ted in Olympia WA

It will be no problem at all.  I would switch a few things that make it look like a 1970 like the front pulleys and intake manifold (you don't want an EGR on a 1970).  Some of the 1976 did not have the smog pump just like your 1970 so the holes will not be in the heads.  If the 1976 did you will have to plug the holes.

What ever you do keep a couple of parts from the 1970 like the crank (the 094 crank is heavier and one year only) and the heads (also sought after by the hot rodders, even though it questionable if they are any better).

If you want to keep the heater hose looking original you can drill the block on the 1976 and use your 1970 as a guide.  You can prevent the shavings from going into your engine by taking out the stat and using a shop vac while you work.  If a few get away it's no problem, they go in the water passageway.  Otherwise you can just take it off the back of the head like they did in 1976 no problem.

If the 1976 came out of an eldo you are okay, but if it came out of a DeVille you will have to switch over the oil pan.  If you end up with two eldo pans don't throw one away, they go for at least $150 with the pick-up.  Also if the 1976 came out of a DeVille you will have to switch over your dip stick and tube, be careful.

Right side rear and front drive manifolds are the same but the driver's side is different.

I doubt if you are but if you are close to Olympia WA I have lots of parts and engines.

The good news is that when you are done you can burn regular gas.

Here's a post I did on another forum about pulling an Eldo engine, I hope it helps.  This is a later one but about the same.  The thing about your 1970 is that there is a lot less room front to rear so you want to pull more off the front.

Selling used Eldorado Parts from 1971-1978.  Member Number 25659.