Caddy Spark Plugs

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gladeslife
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Caddy Spark Plugs

Post by gladeslife »

I just got a caddy that I don't know if its a 472 or a 500 or the year. Need to change the plugs asap but need some advise. What should I use and are there different plugs for the 472 vs. the 500? I did a search but couldn't find anything.

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sidejobs
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Re: Caddy Spark Plugs

Post by sidejobs »

Hei or points ?
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Ruagatr
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Re: Caddy Spark Plugs

Post by Ruagatr »

You need to know if the heads are older 76cc or newer 120 cc heads. If you put a long reach new style plug in the old heads the huge molten piece of metal hanging into the combustion cbamber will preignite and diesel all day long. And short reach in a long head wont ignite worth a damn cause it is covered up. Do not assume that what is in it now is correct. I liked motorcraft or nippondenso or bosch plugs. Use the cross reference book for number once you find out what heads they are. Pull valvcover and read us the 3 digit number stamped in there. Will be 902 950 552 etc. total of six possibilities.

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gladeslife
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Caddy Spark Plugs

Post by gladeslife »

Ok thanks for the reply. I'll pull the cover ASAP and get back to you guys!!!

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gladeslife
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Caddy Spark Plugs

Post by gladeslife »

Hey guys, i pulled off the cover and found these numbers stamped in 4187908. I also saw an 8 with screws on both sides. Any ideas? I'm trying to post pics but it won't work

Ruagatr
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Re: Caddy Spark Plugs

Post by Ruagatr »

No such number. Read the last digit more carefully and it should be a 2. The 8 with a screww on each side is just a foundary number. Check it again and report back and be sure and do bith vakvecovers since people mix and match heads all the time.

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Re: Caddy Spark Plugs

Post by flash »

BEST RATED plugs are,,,,,BOSCH, DENSO, NGK, AC/DELCO,,,all in the IRIDIUM type.

Bosch Platinum +4 are rated 5th,,,,,,,,, This review was for car motors
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gladeslife
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Caddy Spark Plugs

Post by gladeslife »

I'm gonna take both off tomorrow and get back to you. I took pictures to but it's hard to see the number

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TheElevatorGuy
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Re: Caddy Spark Plugs

Post by TheElevatorGuy »

Hey boca......I thought you had a 300 with a jug issue.....I remember reading about it months ago

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gladeslife
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Caddy Spark Plugs

Post by gladeslife »

I had but traded it a few months back. No more getting towed in since.

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crowhater
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Re: Caddy Spark Plugs

Post by crowhater »

flash wrote:BEST RATED plugs are,,,,,BOSCH, DENSO, NGK, AC/DELCO,,,all in the IRIDIUM type.

Bosch Platinum +4 are rated 5th,,,,,,,,, This review was for car motors


There is no reason on earth to run an iridium plug in a cadillac unless you have spent 35-40K on that engine. Its a big low RPM torque building pig and a factory ac delco in the correct heat range will handle the task all day.
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gladeslife
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Caddy Spark Plugs

Post by gladeslife »

1497902 is the number on the heads and the plugs that are in it now are Champion rn14yc. Both numbers are the same. Should I keep using these?

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gladeslife
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Caddy Spark Plugs

Post by gladeslife »

My original numbers were way off. I took a picture and forgot to write them down so I went off of the pic. The new numbers are correct

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gladeslife
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Re: Caddy Spark Plugs

Post by gladeslife »

What do you think Rugar? Any ideas about these numbers? Thanks in advance

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Re: Caddy Spark Plugs

Post by cowtown »

sounds like it could be a 425 , with the castings numbers up in the valvetrain area , but some later model 500 did put it there as well , but not many from what I read . the heads are from 1968 to 1973 , with a 76cc combustion chamber , part store should be able to give you the correct plug in what ever brand you want
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Re: Caddy Spark Plugs

Post by Ruagatr »

Bocaraton: those are the "902's" and are for 68-73 engines with the original pistons. You need to use the short reach plugs. The factory plug in the book for 1973 is fine but get good plugs from one of the 3 manufacturers I mentioned. I assume you are running HEI rather than points. If not, change to the hei and you will notice an immediate improvement. PM me anytime for more data and use the search function on here. Bondsman, Crowhater, Plumcrazy and Sidejobs are all good resources as well. No disrespect meant to anyone else who I forgot. The R in your plugs number is for resister plugs. Do some research and make up your mine on what YOU want to run. If the book calls for a number 14, then a 13 runs colder and a 15 runs hotter. Every engine and setup are different. Be DAMN sure the timing chain has been replaced with a good steel one with steel gears. Search and read the timing chain threads on here.

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sidejobs
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Re: Caddy Spark Plugs

Post by sidejobs »

If your looking for someone to tell you exactly what to use and brand and part # well there are engine tune and condition variables as well as points or hei. Also personal opinions. Ruagatr is right on with his info as usual. Check all the items he reccomends. If you def want a part # autolite 63-66 fit 63 colder , 66 hotter. I have run them all and each engine was a little different. I would reccomened the 64 if your stock engine with hei.
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