How do you power tune an engine?

[George D. Mukalian CLC # 10047]

Could anyone tell me how to power tune an engine. I have a 1970 cadillac eldorado with a 500 cu engine.

Thanks,

George

[Roger Zimmermann]

Ask the "Cad Company" at www.cad500parts.com
Good luck!
Roger

[bcroe]

Before doing that, make sure your maintenance is up to date.  That means you probably have replaced the timing chain and checked the distributor.  If the weights or bearings are worn, you might consider replacing it with an HEI.  Carb & vacuum hoses up to date.  You need a really good dual exhaust for that engine.  Bruce Roe CLC  # 14630

[TJ Hopland]

I think a 'power tune' just means you work on it under load vs. just at idle.   To work on it under load it needs to be on a chassis dyno or you need some sort of portable monitoring / logging equipment to take readings while driving that you can then interpret and make adjustments. 

If you are unhappy with performance like other have said make sure everything is working properly.  Weights in the distributor often get worn or stuck and the vacuum advance often fails with age.  Points often get set wrong but are easy to check and set with a dwell meter.   The only slightly complicated part of this engine is the Qjet carb.   The rest is just basic gas engine stuff that is easily checked with basic automotive tools.   Like others have said the cam gear for the timing chain was covered in plastic in these engines.  Age and mileage are not kind to these.  When most of the plastic falls off the timing gets mushey.  Oddly they do seem to hold together right to the point they fail completely.   I have had many engines apart that I cant believe were still running on what was left of the teeth.  If things are fairly clean you can see the edge of the chain and gear well enough to tell if its plastic and get an idea if its tight or really loose by removing the distributor.  To change the chain properly you need to remove the oil pan which in an eldo means removing the engine.  There are tricks but at this age removing the engine for some other seals and gaskets and a good clean up would likely be a good thing.

MTS  500cid.com is where I get all my parts.  I am 100% satisfied with their parts and customer service.  I cant say the same thing about my personal experience with some other vendors.  Other peoples experiences may be different I cant speak for them.

[George D. Mukalian CLC # 10047]

Before doing that, make sure your maintenance is up to date.  That means you probably have replaced the timing chain and checked the distributor.  If the weights or bearings are worn, you might consider replacing it with an HEI.  Carb & vacuum hoses up to date.  You need a really good dual exhaust for that engine.  Bruce Roe CLC  # 14630

The engine & exhaust has been modified with HEI distributor. Everything is new. How do I power tune it?

[bcroe]

You might check with cadillacpower.com     Bruce Roe  CLC # 14630

[Chris Conklin]

How do I power tune it?

George, Are you asking for a way to do this yourself? I think TJ answered that, you need some portable diagnostic equipment and/or a very well equipped garage of your own. There are plenty of places out there that will "dyno tune" for you. But to have the capability yourself, nothing unusual if you own an older Cadillac, it just takes money. 

Any issues with the car or reasons you feel the need to do this?

[Mike Josephic CLC #3877]

Not really sure what you mean by "power tune" and the extent to which you want to go.

Back many years (40+) ago, we would do a so-called "power tune" by putting in the highest
octane gas we could find (95+) and advance the distributor timing by hand a little at a time. 
We would then run the car up a grade that we could reach modest speeds of 40-50 MPH.

We would continue this over a few runs to advance the timing until we could hear the slighest "ping".  Then, back off a degree or so.  That effectively obtained the highest
value out of the octane available and accordingly the most power.

Note that this was all done "seat of the pants" but it worked well for older cars without
all of the electronic sensors.

HTH,

Mike

[Glen]

Years ago I was told of a way to “power tune” an engine.  IIRC the procedure was with the engine running at a moderate RPM pull the spark plug wires off every other spark plug in the firing order.  Then adjust dwell and timing to maximize the RPM without changing the throttle. 

I’ve never tried it so I can not say if it works or not.  Use at your own risk. 

Glen

[George D. Mukalian CLC # 10047]

Not really sure what you mean by "power tune" and the extent to which you want to go.

Back many years (40+) ago, we would do a so-called "power tune" by putting in the highest
octane gas we could find (95+) and advance the distributor timing by hand a little at a time. 
We would then run the car up a grade that we could reach modest speeds of 40-50 MPH.

We would continue this over a few runs to advance the timing until we could hear the slighest "ping".  Then, back off a degree or so.  That effectively obtained the highest
value out of the octane available and accordingly the most power.

Note that this was all done "seat of the pants" but it worked well for older cars without
all of the electronic sensors.

HTH,

Mike

Thanks Mike. That's what I was looking for.

George