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87 Sunsport
07-17-2003, 07:24 AM
I've been faithfully adding lead substitute to my 87 Sunsport because both the manual and the PCM manual says I should.
I just read a thread elsewhere that says it's useless in any engine build before 74, something about hard vs soft valve seats and the fact that the substitute doesnt do anything anyway. Any one know the truth on this?

John D
07-17-2003, 02:06 PM
I have an 84 comp. I wrote PCM about this very question and they said it depended on what heads you have on the motor. If the heads are prior to 1974, the motor does not have hardened valve seats and requires the lead substitute. If the heads are newer than 74, the valve seats are hardened, and the substitute is "optional". How do you know what you have? If the spark plugs use a 5/8" wrench, you have the new ones. If the spark plugs use a 13/16" wrench, you have the old ones. Note: give me a fax number and i will send you the letter.
John D