1972 Cadillac Eldorado - air pump is it needed

[Scot Minesinger]

Working on a 1972 Eldorado with orders to straighten it out.  The metal tube that connects the two heads to the air pump is missing, but the air pump, belt and all remains.  The roads are loaded with salt and so I cannot drive the car to see how it runs.  I have a 1/4 mile stretch of road that is not slated and it seems to be OK at 25mph, idles OK, and starts good.

The owner wants a decent looking, great running, and reliable car.  He is not concerned with 100% authenticity.

Question:  Will the car run well without the air pump?  Does the air pump improve performance, economy, or provide any benefit save less emissions?  If the answer is no need for air pump, I plan to plug the holes in the heads and remove it completely, and there will be an unused drive pulley groove.  If the air pump is needed, will track down the metal tube used and install.

[joeceretti]

Track down the metal tube and install it for when your customer is gone and someone else gets the car. For the sake of keeping as many of these cars as original as possible.

EDIT: Sometimes you get the answer, sometimes you get opinion. I hope you get both.

[TJ Hopland]

Running without it does not seem to bother these especially the pre cat models like this one.  Before you work too hard to find one test the diverter valve on the pump.  If its not working it will pump air in the exhaust all the time which then makes it do that really annoying backfire pop thing on deceleration.  I seem to remember someone here saying it was very difficult to find one of those valves. 

If the holes in the heads are not plugged they will be exhaust leaks.  I have not tried it but I have been told a coin is a perfect fit.  Maybe a dime?  Doesn't seem like they were big enough for nickels but maybe.   I was ordering other parts from MTS and got the plugs from them.   

You can't just eliminate the belt.  If you look closely you will see that belt runs smog pump, water pump, crank.   The second groove on the water pump is what runs the alternator.  The alternator belt does not go down to the crank.   Without the smog belt there is nothing to run the water pump which also means no alternator.   The non smog cars had a different crank pulley that had the front groove spaced out about an inch from the rear grooves which then aligned with the alternator and a single groove water pump pulley. 

["Cadillac Kid" Greg Surfas 15364]

Scott,
The answer to your question is yes, the car will run just fine without the air pump.  I pulled mine off my '72 years ago (I think I still have the parts I pulled off), and got a three belt pulley set (1970) to run the Water pump and alternator.  If you remove the pump and piping, be sure to plug the holes in the heads and cap/plug the vacuum lines.
If I remember correctly I did not have to do anything to the "tune" after removal.
Greg Surfas

[The Tassie Devil(le)]

If you aren't plagued by the Pollution Police, then there is no need to run the AIR Pump, and all the mess that goes with it.

I have removed three of these things so far, and never a problem.

I also modify the alternator bracket to sit the Alternator rearward so it is inline with the original pulley system, and get rid of the excess weight.

Bruce.

PS.   No requirement for Pollution Controls down here.   Even Cats after the vehicle has done 80,000 miles.

[Scot Minesinger]

TJ Hopland, Greg,

Sounds like removal is in order.  I did not look too close at the belt system.  What 1970 pulleys do I need, the drive pulley and water pump pulley?  And guess they must be for an Eldorado, not a RWD (or hopefully they are all the same)?

[TJ Hopland]

Eldo or C car does not matter for the pulleys.  75.5-79 Seville was the Olds so that won't work.    1970 seems to be the only year for the dual AC belt style 68-74 that didn't come with smog.   75 & 78 are also common years not to have a smog pump but those had the single groove AC belts so there would be other things to change.  Not a big deal if you don't have AC or working AC because you can just replace it with the later stuff.  Pulleys from a 6.0/368 will work too if you are going with the single belt AC.

The 'conversion' stuff should be sold as a set which is the crank pulley, water pump pulley, and the timing indicator.  Over the years there were slight differences in the diameters so if things are mixed they may not match.  The smog water pump pulley will be 2 groove the not smog is a single so that is another clue if you are looking at a true set.

The 68-74 stuff will have the back 2 grooves very close together and then a slight space to the smog groove.  The non smog version will have a much wider space like 3/4-1" to the front groove.    The later stuff is the same except only one rear groove. 

The dual groove era stuff had a bolt on PS pulley.  Most of the single groove stuff was press on.  I think there was only a brief period in 74-75 there were single groove bolt on pulleys so they are very difficult to find these days.   

The commercial chassis with the 100 amp alternator option had another crank pulley that looks to have bolted inside the standard pulley to add an extra groove that directly drove the alternator.  I never saw one of these that was non smog. 

[Scot Minesinger]

Thanks will get a set of 70 Pulleys.  I will be sure to have the timing mark in same place when changing out drive pulleys (diameter will not impact timing mark).  Looked at modifying alternator brackets to move it back so that would not have to change the drive and water pump pulley, but there is not enough clearance with alternator and it would strike the head.

[TJ Hopland]

You have a for sure source for 70 pulleys?  That must be nice, maybe we should come to you (or your 'guy') for all our 70's needs?  A lot of that sort of thing is getting hard to come by through typical junkyards.

The bolt holes in the crank pulleys are slightly offset so you can only easily make it fit one way.   The reason you want the timing indicator that belongs with that pulley is apparently they didn't always put the mark in the same place and the diameters could have been different so they are difficult to use if you have the wrong combo.    It may not be an issue if you are sticking with the earlier stuff but for sure when you get the later stuff you can run into issues.   

When I got my first Caddy it ran best at like 5* after which made no sense but I didn't really care because it ran good.   I think it was a 71-73 engine with 75 pulleys.   I think it was when I was changing to non smog pulleys I noticed the difference in the markers.  Luckily I had read to get the marker when I bid on a pulley set on ebay, I asked the seller if I could have the tab too.  Luckily he said I caught him on the way to the scrap yard so I got it.  I think with the new pulleys it was off a several degrees the other way till I switched to the one that came with the set.  That ebay set I think came off a 78 which has stamped pulleys and a plastic tab.   I think the earliest tabs were metal and didn't have the hole for the probe. 

[Scot Minesinger]

I will carefully mark where timing mark is on pulley against engine housing mark, and file a new timing grove if needed.  Yes, will be searching for those pulleys, do not have them yet.

[TJ Hopland]

MTS sells a 'kit' for around $275.  It includes both pulleys, a belt, the plugs for the heads, and some hardware.    You can use that as a benchmark or what you should pay for used stuff or offer that as an option to the customer.  Depending on what / if you charge for your time searching for used parts it could be a good deal for him just to buy it from MTS.   I would imagine painted they won't look much different than stock. 

["Cadillac Kid" Greg Surfas 15364]

TJ,

"Depending on what / if you charge for your time searching for used parts"

This is supposed to be a non commercial site.
Greg Surfas

[Scot Minesinger]

I was planning to call MTS anyway on Monday, so that settles that.  For the record do not charge for parts search time, or time on forum.  The car repairs I do are for fun and more helping out local CLC members than a means to earn a living. 

This is an escape from my lucrative, but painful day job.  I just do not enjoy my engineering consulting company very much anymore because it is not about engineering, and a lot more about running a business and dealing with way too many non-engineering people who think their alluring personality changes the laws of physics.  There remain some good people in the industry though.  I should just stop typing now as it is way off topic.

This subject is totally resolved, thanks for the input, know exactly how to proceed.  Don't worry if you enjoy posting about 1972 Eldorados probably will have a few more subjects in the next few weeks.

[The Tassie Devil(le)]

Moving the Alternator is not a big problem.   Just requires a bit of cutting, grinding and welding and some deft use of the vice and some heat to re-bend the top adjusting arm.

Ignore the welded-up original AIR block fitting, as that has now been changed for the correct plug.

Not sure what the double pullied Alternator is from, but it was on the car when I purchased it.

Bruce.

[TJ Hopland]

TJ,

"Depending on what / if you charge for your time searching for used parts"

This is supposed to be a non commercial site.
Greg Surfas

I don't get what you are saying with your above statement.   What is commercial about that?  I did mention a specific vendor but you didn't quote that.   

My intent was to point out to Scott and anyone else considering this sort of swap that you can buy a new pulley kit for $260.   At first glance that seems like a lot of money but if you spend a few hours searching online or driving to a junkyard and then pay say $75 for the parts you may or may not have $260 invested depending on how you value your time.  If this was a shop situation at $100 an hour new would likely be a pretty sweet deal.   I knew Scott was working on this for someone else but didn't know the details so I wanted to give him more info and options to help him and his friend / customer decide what to do.     

[Scot Minesinger]

Bruce,

Very clever.  My measurements indicate that 7/8" back movement is required, and it could be done.  Thing is would have to move alternator back and away from drive pulley to clear current alternator and that would only give an 1/8" of clearance.  If it was the only way, I would do it.  Since I can just buy all the parts already engineered to overcome the issue it will be easier.

[Scot Minesinger]

TJ Hopland,

Thanks for the comment, it is what I will do buy the set up from MTS.  Even if this was my car, your point stands about time, because I have no free time to sit and do nothing.  Anytime some time can be saved, always try to do it.  Please keep posting as you have always done.  I try and always consider my friend's cars like my car. 

[TJ Hopland]

So now that Scott has a plan we possibly go slightly off track and explore Bruce's idea.   

I have heard about Bruce's move back before but never saw the photos.  Interesting.  Are any of the newer alternators less deep than the 10si's we are normally dealing with on these engines?   I learned from some other swap sites that many of the pulleys interchange so in theory if you found a newer unit with a serp belt you could swap the V pulley on it.   There are limits to how many amps you can get off a single V belt but maybe there is a newer much more compact alternator with a similar output to stock that could be adapted by someone with little to no fabrication skills?   I'm just thinking how much smaller in diameter the 100 amp one was I just changed on my truck.  I should go see how the depth compares.   The one on my truck even has basically the same mounting points as the earlier ones even though its a serp setup with a tensioner instead of using the alternator as a tension device.   The truck today was a 95, I think the one on my 96 has a different mounting method so that may be around the cut off year for easy possibilities. 

[cadillacmike68]

I have a 100 amp (chromed) Delco alternator on my 1968 and it is slightly smaller than the original one (which I still have). I originally had some strange bracket gymnastics when first setting up for no AIR pump (so the newer alternator has no issue with head clearance) , but got a set of 1970 pulleys, because it didn't look right at all otherwise.

[TJ Hopland]

Mike, so you have a 'smog' car and pulleys with a slightly smaller alternator that make the belts work without as much bracket fabrication as Bruce had to do?   If that is what you have it would be cool if you can figure out what application or model that alternator is.   I bet a lot of people would be interested in a fairly low cost minimal / no fab option like that.