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Why are my head bolts different lengths?
Posted: Wed Feb 14, 2024 2:23 pm
by Jonah D'Avella
My head bolts are different lengths, is that ok?
Re: Why are my head bolts different lengths?
Posted: Wed Feb 14, 2024 2:35 pm
by TRDxB2
Jonah D'Avella wrote: ↑Wed Feb 14, 2024 2:23 pm
My head bolts are different lengths, is that ok?
Doubtful. Low, high or accessory head?
Low head bolt 2-3/4" from under the head to the end of the bolt
High head bolt 3-1/4" from under the head to the end of the bolt
Are the bottom of the holes in the block cleaned out thoroughly? Maybe why someone used different ones.
Re: Why are my head bolts different lengths?
Posted: Wed Feb 14, 2024 3:23 pm
by Jerry VanOoteghem
Jonah D'Avella wrote: ↑Wed Feb 14, 2024 2:23 pm
My head bolts are different lengths, is that ok?
Probably not. It would be best to order new bolts and be sure they go in at least 1-1/2 diameters. Meaning 1.5 x 7/16" = 11/16". 3/4" or even more would be nice too. However, be certain that they do not bottom out in the cleaned-up threads before reaching the final torque.
Re: Why are my head bolts different lengths?
Posted: Wed Feb 14, 2024 4:09 pm
by Jonah D'Avella
I checked and they looke to be the same length, but the threads are different lengths. I cleaned and ran a tap through all the holes
Re: Why are my head bolts different lengths?
Posted: Wed Feb 14, 2024 5:53 pm
by Norman Kling
Two important things. 1. Bolts should all be the same height when screwed all the down in the block. 2. The threads should not end before the bolt bottoms out. If this is so, try the bolts in the head and block without the gasket. The heads should go down far enough to touch the head when installed without the gasket. If all these are true, you can install the gasket and it will have a turn or two to torque the head. Note, if one of the bolts bottoms out before it is all the way down, the torque wrench will read full torque when it bottoms out, but it might not be pressing down the head all the way. If you shorten the bolt, be sure to shorten them all so if they get mixed up, it will still tighten all the way down, or you can do like I did and always use a washer on the bolt in that location.
Norm
Re: Why are my head bolts different lengths?
Posted: Wed Feb 14, 2024 7:51 pm
by DanTreace
Jonah D'Avella wrote: ↑Wed Feb 14, 2024 4:09 pm
I checked and they looke to be the same length, but the threads are different lengths. I cleaned and ran a tap through all the holes
The later nickel plate dome head bolts have a little shorter thread length. But only a small lower section of the threads go into the engine block.