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Can the 76 Eldo be "retuned" to increase the horsepower?

Started by Dean, August 27, 2008, 11:43:19 PM

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Dean

Hi: I might be asking a dumb question but I'm interested in 76 Eldo's. Can their horsepower be increased to the 72-74 levels?Thanks,Dean.

TJ Hopland

Yes. Its not simple like 'removing the restrictor plate'.  Change the cam.  Do some tweaking on the carb. Do some tweaking on the distributor. Get rid of that manifold thing that the cat converter bolts to (if you ever saw one you would wonder how you could even flow a 350 through it, of course I guess you could look at the snorkel on the air cleaner and wonder the same thing).     Problem #1 is to change the cam you have to pull the timing cover.  Technically to pull the timing cover you have to remove the oil pan.  Step #1 for oil pan removal in eldorado is remove engine.  There are parts out there to build a 472/500 to about any level you want or can afford.  Displacement was always the same.  Compression changed in 71.  Heads changed in 74 but left compression the same due to different pistons.  One other bad thing about these motors (really any 70's-80's nicer cars) is the timing chain cam gears had plastic teeth.  They dont hold up well with mileage and now age.  My car had 70K on it when I got it and the gear looked fine except for a couple of cracks.  2 years later I cant believe it was still running because there was so much missing.  Basically if you plan to drive the car longterm the engine should come out for at least a 'freshing up'.   Timing set, seals, gaskets, and maybe a cam/lifters.  If its running good you should not have to pull the heads but it will make it easier to change the valve seals that are much like the timing gear and likely in the oil pan by now.  The oil pumps were aluminum and did not hold up the best either.  It kinda gets to be a might as well thing but if you want to drive the car its worth it.  I drove mine for 9 years before I got sick of the leaks and saw how much of the gear was missing.  Drove it another 2 after that.  Now have a rebuilt motor with an EFI system on it that I made from random parts.
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

Ted in Olympia WA

The cam is the same so that won't help.  The main thing is the exhaust.  If you take off  the cat and put of good exhaust on it will be right back to where it was.  But an mild aftermarket cam change will help and it is a good idea to change the timing chain.

You can replace the cam without removing the pan but you have to know the tricks.

You need to pound the dowel pins in a bit, I don't pound the dowels all the way out.  It just pound them down so they are out of the block about 1/8"-3/16" (flush with the top of the cover, or slightly below.  When you get the cover back on they are no longer long enough for the timing pointer but the one bolt will hold it.  They are just long enough to go throught he gasket and into the cover.

When you put the cover back on;  The rubber that goes on the front of the pan has several tits.  put them through the holes with lots of silcone and then attach a pair of vice grips to each one of the tips on the bottom side.  This will make sure the tips stay in the holes and you don't loose the rubber.  Then when you put on the cover back you have to tilt it to one side and kind of rotate it in place,  this may take several attempts but when are just about to give up it will go on.  Use a big round screwdriver and line up one of the hole while you start a bolt on one of the others until you get them all.

Make sure you use a true roller timing set, not the cheap replacement set.  We have seen more than one cheap set break the crank gear and ruin the engine.  This is not a good place to save $75.

I hope this make sense.

But the main thing is the poor exhaust and also advance the timing as much as possible without pinging.

The other problem is that most early Eldos have 3.07 gears and the later ones mostly have 2.73.  This makes a big difference in the feel of power.

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

Guidematic

 That's right. Perhpas the biggest culprit to performance on these cars is the exhaust. 500 cid needs to breathe, and the combination of that cast iron adaptor, the covertor and the little air cleaner snorkel conspire to really limit power. And,those dual bed convertors are notoriously restrictive.

Marty(?) from MTS put an air cleaner on the flow bench ans found that it flowed a measly 380cfm! Simply installing a smaller lid will fix that problem.

All other things being equal, these 2 things will bring a good and useable increase in performance at a minimal cost.

Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

Stampie

How about simple tuning?  This post is a little old but for an hour of your time and about zero cost you can get a lot out of your 500.

http://www.modifiedcadillac.org/forum/index.php/topic,5.0.html

Stampie
If... the machine of government... is of such a nature that it requires you to be the agent of injustice to another, then, I say, break the law.  ~Henry David Thoreau, On the Duty of Civil Disobediance, 1849

If we desire respect for the law, we must first make the law respectable.  ~Louis D. Brandeis

eam 17806

#5
MIKE!  EXPLAIN IN A LITTLE MORE DETAIL, IF YOUY WILL, CONCERNING A SMALLER LID ON THE AIR CLEANER? I HAVE A 76 WITH A CARB AND I ALWAYS HAD A QUESTION AS TO WHY THEY REARRANGED THE INFLOW OF AIR TO THE CARB FROM COMING FROM THE FAN TO DIRECTING THE FUNNEL TO THE FRONT GRILLE.  THIS SEEMS TO ME TO DIMINISH THE AIR FLOW TO THE CARB ESPECIALLY DURING IDLE AND IN HEAVY TRAFFIC.  i WOULD LIKE TO READ YOUR THOUGHTS ON THIS.  EAM

Guidematic

 I installed an air cleaner cover that just covers the top of the element itself, leaving the cicimpferance of the air cleaner base open.

These hoses, or ducts, were simply to channel cooler outside air into the aircleaner. The '75's had an intake muffler attached to them as well.

  http://ca.youtube.com/watch?v=aYv_G-d1szo

Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

eam 17806

#7
MIKE!  I ACHIEVED THE SAME RESULT AS YOU DID GETTING ANOTHER AIR CLEANER COVER BY JUST INVERTING THE AIR CLEANER COVER ON MY 76 AND IT EXPOSES THE AIR CLEANER ELEMENT PERFECTLY.  THE RESULT INCREASES THE GET UP AND GO QUITE A BIT.  THANKS FOR THE THOUGHT!  EAM

Ted in Olympia WA

Nothing beats the sound of a Q-jet opening up in an open air cleaner.

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

TJ Hopland

#9
I miss that with my efi, ya there is a sucking sound but not quite like that slight woosh as the transmission downshifts and those secondaries open.  Sort of the calm before the storm
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

Guidematic

Quote from: Ted in Olympia WA on August 31, 2008, 10:59:23 PM
Nothing beats the sound of a Q-jet opening up in an open air cleaner.

TED

Especuially if it's on top od a 472 or 500

Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

eam 17806

#11
 Mike:  I did what you suggested above by inverting the air cleaner cover as I stated earlier and I like the result but bear in mind the crankcase breather now becomes useless, the fumes are blowing into the air and not through the air filter element and into the carb to be burned as intended.  Will this be any harm to the atmosphere or do you think some or most of it will be sucked into the carb instead of going nowhere but into the atmosphere.  I realize its one or the other.  What are your thoughts?  EAM

Ted in Olympia WA

If you were worried about the atmosphere you would not be driving a 75 Eldorado.

Also this is a air intake for the pressure sucked out by the PCV valve and a good running engine should not have any coming out here.

At least this is how I understand it.

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

Guidematic

#13
 That is correct. There are a couple of reasons that it may be doing this. Fist it may be a plugged or non working PCV valv, the other could be excessive ring blowby. Since the 500 engine is a very sound engine and rarely has ting issues, I would tend to go with the PCV.

Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

"Cadillac Kid" Greg Surfas 15364

Dean,
You have gotten a lot of suggestions in response to your question of increasing the power.  My question to you is "Is the power you currently have, (assuming all systems are functioning) enough for your performance needs of this luxury car?
Much of the sensed decrease in power is due to the smooth operation of the 75-76 motors.
My "tired" 200,000 mile 472 motored 73 coupe deVille pulls a consistent 16.2 seconds at close to 90 MPH in the quarter.  It doesn't feel fast, but it weights 5200 pounds.
As others have said, you got the "gozinta" and the "goxouta". The intake and the exhaust tracts.  Be sure everything is functional and working correctly and performance will be commensurate with a near 5500 pound vehicle.
That said, if you have unlimited funds and aren't a stickler for originality, go over to the Modified Regions forum and we can give you suggestions on how to spend your heirs inheritance chacing the power Genie.
Greg
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

76eldo

I had my 76 out on Sunday.  Took a nice drive, out for dinner, crusing nicely on the PA turnpike a 70-75, air on, running strong.

At a light, couldn't even feel it running.

I did notice a whooshing sound on acceleration, like a pinched tail pipe or something.

I have thought about eliminating the cat, and having a set of custom duals installed, but I would have to have twin mufflers and resonators, with the little slant on the end of the pipe.  Ideally, it should look exactly like the stock setup, just on both sides.  A Cadillac should have a nice authoritative rumble, but not be too loud, and I hate that highway drone of a car with too much sound at the tail pipe.  It's cool for a muscle car, but not a Caddy.

I would think that getting rid of the restrictive exhaust would have to help out a bit, and the small lid for the air cleaner is a GREAT idea, easily reversible for show.

Brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

TJ Hopland

If you look at that Y (more of a T) pipe manifold thing that the cat bolts to you will wonder how the thing even runs.  At least the non cat eldos had more of a Y pipe.  Problem is getting everything to fit under there since the 71-78's were never designed to have dual.  I dont think there is any way you are going to get 2 mufflers and 2 resonators stuffed up where they cant be seen.  Wanting a little rumble helps because the mufflers can be smaller but I think the size that fits will be too loud.  I started out with 'turbos' on mine.  Ended up paying twice what the whole system cost me 2 weeks later to get big truck mufflers installed.  They have the sound you are looking for.  The gas tank is shifted to one side to leave room for the resonator and the other side barely has room for a pipe.  The control for the air ride gets in the way unless your guy wants to get extra creative in the bending.

I dont seem to have any pictures of just my exhaust but you can see the mufflers in this shot.  The bends could have been tighter to pull the right one up a little but the wont fit much higher.   I use mine to tow my boat and they often hit on the ramps.



On the drivers side you can see the corner of the pipe behind the wheel.  It cant get much tighter because of the offset in the tank and the way the frame work is back there.  I dont seem to have a tighter pic but you can see it in this one and if you look at the above one you can see where the left pipe has to run almost below the tank to get around while the right (stock location) is well hidden.


I always thought about getting chrome tips.  11 years now and counting.


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

76eldo

Thanks for the info and photos.

I guess just getting rid of the restrictive part of the system would help, even if I have to keep the single exhaust from the cat back.

No local muffler shops will remove the cat, but since I have a PA antique tag, requiring no inspection or emissions testing, they said if I brought it to them with the cat already gone, they would work on it.

If I get to it this season, I will report back.

Brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

Guidematic

 Another thought. Instead of going with dual pipes, go with a single larger diameter pipe and a freer flowing muffler. A 3" system can flow as much air as a pair of 2" pipes. I know most of these Cadillacs run a single 2 1/2" pipe, but the added flow under most circumstances with a single 3" may prove worthwhile.

But, I do understand that bending a 3" pipe over the axle may prove toublesome, but a good shop should be able to overcome that.

On mine, I run 2.5" pipe, through a Walker Quiet Flow muffler and no resonator. It seems to work well for all except WOT where I know it can get restrictive.

And, BTW, my '88 Eldo uses a 2.5" pipe for the 4.5. I have eliminated the cat and the exhaust sounds quite nice and is more than adequate for the 4.5.

Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

TJ Hopland

If I ever get around to doing a new system I was going to find a guy that knew what he was doing and have him do a over sized single just because of space issues.
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