70's Cadillac intake manifold

[1976Deville]

Hi everyone,
I have a question on a intake manifold. I have a 1976 Cadillac Eldorado ( need restoration ) . Used to have a fuel injection, but the car got converted by the previous owner to propane. So many parts are missing. I would like to install a carburetor in the car so I need to change the intake manifold. Our local Pick and pull has a 1978 De Ville and a 80 Fleetwood in the yard. Does the intake manifold from these cars will work on a 500  Eldorado engine?
Thanks Herbert

[chrisntam]

The engine in the '78 is likely a 425.  I'm pretty sure the engine components (intake) are different.

Someone will chime in to be sure though.

["Cadillac Kid" Greg Surfas 15364]

Herbert
The 789 would be a 425 and I believe the 80 might be a 368. Neither of which would be what you might want. You would want a 1974 through 1976 intake from either a 472 or a 500.  These will be correct with the EGR and the Electric choke (no choke mounting on the intake. I don't know where you are so shipping might be an issue but PM me if you are interested in one that I have.
Greg Surfas

[1976Deville]

Hi Greg.
Thanks for the reply. Yes the shipping is to problem. I live in BC Canada. and these manifolds are heavy. So I was hoping the 78 would fit. Crab and everything else is still on the intake. Maybe not correct for the year but better than nothing

["Cadillac Kid" Greg Surfas 15364]

Herbert,
You will find the later intakes quite restrictive and unless you don't mind a noticeable drop in performance I would hold out for the earlier model.
Greg Surfas

[1976Deville]

Thanks Greg

[bcroe]

According to my parts book, 76-79 500 and 425 with EFI all use
the same intake manifold.  So a 425 intake certainly will fit.  For
some reason the 76 intake for 500 with carb isn't listed. 

Certainly don't use 80-81 parts for a 368, which is a much redesigned
engine.  Bruce Roe

[1976Deville]

Thanks  Bruce. Some good news

[Scot Minesinger]

Agree with Greg use the 1974-76 manifold.  The extra shipping for a correct manifold is worth it.  A year down the road with an incorrect manifold, lower performance, things not right, you would gladly pay the extra shipping costs if you could do it over.  1977 was the start of a GM diet for the large cars, and they shed 1,000lbs or so from 1976 to 1977, and a smaller intake manifold was likely part of the program but not well documented.

The saying "price is forgotten ... and quality is remembered" has an application here.

["Cadillac Kid" Greg Surfas 15364]

Bruce,
If I wasn't so lazy I would take a side by side picture of the two intakes.  The intake for the '79 is
"tucked down a bit and the intake path is a bit more torturous.
GregSurfas

[1976Deville]

OK, but the main thing is I could use it temporarily. It is only $25.00. I always can buy one next time I drive to Arizona. Like I said, the car needs a total restoration and I do not know when I have time to do it. Working on a 63 Mercury. Would be just nice to move the car once a while

[bcroe]

Bruce, If I wasn't so lazy I would take a side by side picture of
the two intakes.  The intake for the '79 is "tucked down a bit and
the intake path is a bit more torturous.  GregSurfas 

Thanks, I don't have a 77-79 intake to look at, and my parts book
seems to be incomplete on this.  But using a cheap sub till the real
one is convenient, sounds like a good idea.  Bruce

["Cadillac Kid" Greg Surfas 15364]

The $35 or $40 wasted on an extra intake gasket set could pay for a bit of shipping, IMHO
Greg Surfas

[1976Deville]

Hi Greg but not to Canada
I guess shipping will be around 120.00 US. plus import tax, Broker fee plus a Canadian Dollar 25% less them the USA Dollar.
But I know what you are saying.
Would be nice to see both next to each other

["Cadillac Kid" Greg Surfas 15364]

Okay, okay, okay okay.  You MADE me go outside and here is the results.  The 76 intake (the muddy one) and the 425 intake (the rusty one.
Differences: 76

1. 76 is dual plane, 425 is single plane
2. EGR is different
3.AC Bracket mounting holes is different
4. mounting for the transmission kick down switch is different
5. Look at how much the 425 (rusty one) is collapsed into the block valley and how small the plenum under the carb is.
The 76 is choked down enough.  I would guess that the 425 intake will flow probably 25% less and most of the accessories that are fitted to the intake, won't.

Alright I am don e with this. I am getting ready for a couple of weeks on the beach in Hawaii and car stuff takes second fiddle
Greg Surfas

[1976Deville]

Ok ok , I just wait until I drive to the USA again. and get one from a 500 engine. So the 472 not work either.
And thank you for the work with the pictures.

["Cadillac Kid" Greg Surfas 15364]

472 and 500 are the same but 75 and 76 were 500 “ motors only, so if you want all the accessories to fit correctly you want 75 or 76
Greg Surfas

[1976Deville]

Thanks Greg.
So I will go with the correct 500 intake

["Cadillac Kid" Greg Surfas 15364]

Good call.
Greg Surfas