QuestionQUESTION: I'm looking for the most current specification on tightening the head bolts on an 84 ford t-bird with a 3.8L engine (non-supercharged). I've looked up the procedure in Chilton, but read that some of ford's head bolt procedures have been updated numerous times. Is this one of them? When attempting the procedure I have, it "felt" strange when doing the final 90 degree angle. I had to put FAR more strength into turning the short bolts the 90 degrees than the long ones. Is this normal?
ANSWER: It is apparent that you have not seen the correct information. According to my reference material the long bolts are torqued in 6 steps.
1. 37 ft lbs.
2. 45 ft lbs.
3. 52 ft lbs.
4. 59 ft lbs.
5. Back all bolts off 2 to 3 turns and torque to 11 to 18 ft lbs.
6. Then tighten long bolts 85 to 105 degrees and the short bolts 65 to 85 degrees.
---------- FOLLOW-UP ----------
QUESTION: This is a follow up question. Based on your answer it appears this IS one of their procedures that HAS been updated. But I'm not sure if you got it all right either (or you may have just been incomplete), so I'll include a little more detail, and ask you for a little more detail.
Chilton claimed: tighten all (in order) in four stages up to 59 ftlb (that agrees with you). Then loosen each INDIVIDUALLY (in order) 2-3 turns, then tighten to 11-18 ftlb for the long bolts plus 90 degrees, or 7-15 ftlb for the short bolts plus 90 degrees. This last 90 degrees is what I was saying "felt" very strange, since it required FAR more strength to tighten the short bolts then the long ones.
In your response, you said (in your "step 5") to back off ALL bolts and tighten to 11-18 ftlb (appearing to mean "all at the same time", but you may have MEANT individually), then (in your "step 6") to tighten long bolts 85-105 degrees and short bolts 65-85 degrees.
This last step SOUNDED like a better procedure to me, since it would probably result in a more even final torque than the procedure I used. But should they be done individually or all together?
Finally, if I already tightened them all the extra 90 degrees (described in Chilton), would I be safe simply
tightening the long ones an extra 20 degrees (to match the updated angle)? I think the short ones will be fine, even though I tightened them 5 more degrees than the max.
allowed, because of the fact I didn't tighten them as much initially (15 ftlb, instead of 18 ftlb), this might make up for the 5 degree difference itself. BUT re. the long ones,
if I simply tighten them the extra 20 degrees (to the max. allowed, so they'll be tightened similar to the short ones), the bolts will not be being tightened in the
correct order (since the long ones are all located along the top of the head). This is obviously not the "best" situation, but do you think it would be "acceptable"? (By the way, if it makes a difference, the heads were perfectly
flat prior to installing them -- no warpage at all.)
AnswerSorry for the delay but I was doing some digging to make sure that I had the latest and greatest information. The information is yes loosen all the bolts and then retighten in the correct sequence. The info also tells me that once tightened the recommendation is do not reuse if moving the bolt. I might be inclined to try if this is not your prime vehicle that gets lots of use.
Brad
