What to do on a tune up to the 4.9?
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HT4100 4.1, 4.5, 4.9 Discussion, What to do on a tune up to the 4.9? in Cadillac Engine Technical Discussion; ok, I want to do a big tune up... as much as I can....... I have some things in mind, ...
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    What to do on a tune up to the 4.9?

    ok, I want to do a big tune up... as much as I can....... I have some things in mind, but not sure if anything else should be done.... this is what I have done already:

    air filter (well, I just need to clean my K&N)
    oil change (although I'll do another, it has been sitting a little while)
    I changed the PCV valve today

    I need to do plugs and wires, I found out the distributor is not serviceable (can't change cap and rotor) so what should I do for plugs and wires? Advance auto only has Xact wires ($60) but I think I can do better then that... I was thinking 8mm Accel.... where can I buy them? Also, what about plugs... I have been hearing mixed things about many plugs.... Advance has the factory AC Delco platniums, Bosch +4 and Autolite double platniums... which of these are the best? or should I check out other kinds?

    I also bought a new fuel filter... will be changing that.

    What else is there that I can do?..... Also I want to use the best parts I can get.....

    ...the car has 87k miles on it... runs, drives and looks new.....

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    Re: What to do on a tune up to the 4.9?

    don't forget to set your timing to about 13 or 14 degrees. If you do this, you will always have to use high octane, and even then listen well for spark knock. if you hear it, just turn it down until it just barely goes away. call "top dead ping" you'll see good gains... for FREE!

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    Re: What to do on a tune up to the 4.9?

    yes, I ment to do that today, but wasn't able to get the car started (battery is dead... had to jump it, I didn't have much time and wasn't trying hard enough) but I run premium in that all the time... even in my Oldsmobile winter car (3800 V6) which says it is fine with regular (dosn't like it though) I run premium in.....

    .... how much of a performance differnce are we talking about here... anything noticable?

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    Re: What to do on a tune up to the 4.9?

    no dyno runs to prove anything of course, but seat of pants... you'll feel it... gives it a little more balls in the mid/upper range too, where this ho needs help! i'm gonna say in the 1/4, it'd probably shave .2 or .3?? you'll notice it! better gas mileage too!

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    Re: What to do on a tune up to the 4.9?

    you've been to the track haven't you? what'd you run? There's a 1000 ft track ab. 10 mins from me (just learned this) and I really want to run this weekend, while the weathers cool and baro up, but we'll see.

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    Re: What to do on a tune up to the 4.9?

    Quote Originally Posted by Night Wolf
    ok, I want to do a big tune up... as much as I can....... I have some things in mind, but not sure if anything else should be done.... this is what I have done already:

    air filter (well, I just need to clean my K&N)
    oil change (although I'll do another, it has been sitting a little while)
    I changed the PCV valve today

    I need to do plugs and wires, I found out the distributor is not serviceable (can't change cap and rotor) so what should I do for plugs and wires? Advance auto only has Xact wires ($60) but I think I can do better then that... I was thinking 8mm Accel.... where can I buy them? Also, what about plugs... I have been hearing mixed things about many plugs.... Advance has the factory AC Delco platniums, Bosch +4 and Autolite double platniums... which of these are the best? or should I check out other kinds?

    I also bought a new fuel filter... will be changing that.

    What else is there that I can do?..... Also I want to use the best parts I can get.....

    ...the car has 87k miles on it... runs, drives and looks new.....

    I hope you have small hands !!!!
    The back plugs aren't so bad, but the front ones are a bitch, especially the two passenger side plugs.(I have the same 1993 car but it's a sedan deville)

    I used bosch wires and regular (single) bosch platinum plugs, they are fine and only cost $2 for each plug $30 for the wires. And the cap and rotor ARE serviceable (just did em tonight). And for $30 bucks change the O2 sensor too, you'll get that back in saved gas quickly

    Don't do the bonehead move I just did, be careful how you route the plug wires ! Some of them will be too long and can hit hot exhaust pipes !

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    Re: What to do on a tune up to the 4.9?

    Why would your distributer cap and rotor NOT be serviceable??

    As for plugs, I've read on this Forum (someone knowledgable) to stay away from the 4's from Bosche. Something about the gap (I know it's factory gapped) not being good because of the design. I went with the original Bosche Plats, and couldn't be happier.

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    Re: What to do on a tune up to the 4.9?

    Is there just one O2 sensor on these? Where is it located? What about throttle body and injector cleaning? How difficult? What is the best way to do them?

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    Re: What to do on a tune up to the 4.9?

    oh yeah, forgot about the O2 sensors... IIRC there are 2 (there was a thread about it)

    .2-.3 in the 1/4? wow... that's quite a bit.... when I raced i ran a 16.0 @ 83mph... trunk was stripped (spare tire and jack out) had 14gallons of gas in the car, I also had octane booster in there.... IIRC my K&N air filter was installed.... don't remember, and that was my first time at the track, so I launched the car pretty bad.....

    The guy at Advance Auto said the dist wasn't serviceable, and that they don't have a cap and rotor for it.... I want to use premium parts, best wires/plugs/cap+rotor I can get too....

    When looking at the back plugs, they seem inpossible to get!..... do you have to go from the bottom?

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    Re: What to do on a tune up to the 4.9?

    Really?! I had an accell cap and rotor along with a Super Coil. It's the normal GM HEI ignition. You need to find a new parts store man. Try using MaxLife oil, it actually helped mine a bit. As far as plugs get the Delcos, all that other junk is useless. One thing I have done and liked was grind down the top electrode untill its a only overlapping the bottom one by a little bit, and then regapping on an angle. I read it in an old Smokey Yunik book, and it seemed to work on my old caddy. I get the plugs from under the car, but I have a lift to use... Could probably still do it on your back thought....

    D.

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    Re: What to do on a tune up to the 4.9?

    Quote Originally Posted by HippieD9 View Post
    Really?! I had an accell cap and rotor along with a Super Coil. It's the normal GM HEI ignition. You need to find a new parts store man. Try using MaxLife oil, it actually helped mine a bit. As far as plugs get the Delcos, all that other junk is useless. One thing I have done and liked was grind down the top electrode untill its a only overlapping the bottom one by a little bit, and then regapping on an angle. I read it in an old Smokey Yunik book, and it seemed to work on my old caddy. I get the plugs from under the car, but I have a lift to use... Could probably still do it on your back thought....

    D.
    Thanks for the advice!

    Though this thread is now 4 years old..... the '93 Coupe DeVille in question was stolen and never to be found in July '06.

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