First of all you can get a Chilton or a Haynes manual at any Pep Boys ,Checker Schucks Kragen ,Auto Zone ,Napa ,and at bookstores like Borders ,Barnes and Noble ,and Amazon.com... Now for the firing order all late model 302 H.Os like yours are the same has any 351W from 69 on up... 1-3-7-2-6-5-4-8. The 302 had a different firing order prior to 79 in 'Stangs (all non H.O vehicles with 302s after 79 kept the original firing order though) that was 1-5-4-2-6-3-7-8. Now that you said your car was a 83 it should have the late model firing order for a 302 H.O. If not whoever owned the car before you may have routed the wires the non H.O way... That could cause a definite backfire... Don't forget to check the other components I mentioned either good luck!:thumbsup