Spark Plug Replacement

[luxury_lemans]

I'm restoring my 1972 Luxury LeMans, 350 cubic inch engine, V8. It has about 216,000 miles on it, as it is the original 42 year old engine and hasn't been modified. I recently pulled the spark plugs and saw that it's burning a lot of oil. The old spark plugs were ACR45TS. What is a safe plug that will fit my engine and will be most compatible with the size and age? Once I get the spark plugs, I plan on running a compression check. How much compression should a 1972 350 motor have?

 

[Rastoy]

I use ACDelco R45S. Gap should be .035 (I just replaced mine).

 

[melsg5]

The correct spark plug is the R45TS and the compression is 120 to 160 PSI. Rastoy has a different year, 1971, and it uses a different spark plug.

 

[Rastoy]

Melsg5 is correct, I just checked my Haynes Manual. Didn't realize the change after '71.

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[Icefan71]

I did a compression test on my 72 Lemans 350. I had 120-124 psi on all 8 cylinders. The important thing is that all your numbers are very close. If you have oil on your spark plugs you may have worn valve seals or worn piston rings.

 

[Kevlar]

Icefan71 is correct in that all cylinders be close in a compression test. The rule of thumb I was taught in the old days was 10%. So, if your highest cylinder reads 130 the lowest should be at least 117, the closer the better. This lets you know that your rings and valves/seats are still sealing relatively well and the cam hasn't slipped timing.

 

[luxury_lemans]

Will a local auto parts store sell these spark plugs?

 

[melsg5]

Have no way of knowing what stores in your area sell AC Delco plugs but they would have an equivilant.

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