New Head Bolts?

[Campbell Tellman]

My 1916 Ford Touring car has had an engine swap. It has an almost 11,000,000 replacement. I have been checking it out and I would like your advice about reusing the original head bolts or buy new ones. They came out easily and appear in good condition.
Thanks for your input.
Campbell Tellman II
1916 Ford Touring
Beaufort, NC

[Norman Kling]

Run a bottoming tap down into the threads and blow out all residue. If the threads are good on both the bolts and the holes you can use them.
also clean out all rust and oil from inside the water jacket on both the block and the head. Then when you are all done and ready to use the block with good babbit on all bearings and caps and good alignment of the center main you are ready to go. Remember that the weight of the flywheel and magnets will tend to pull the back of the crankshaft down which will flex the crankshaft high in the center and eventually lead to a broken crankshaft. So be sure all the journals are in alignment and that the 4th main is centered The Model T is a bit harder to keep things in alignment than the Model A.
Norm

[RGould1910]

Yes, I've used original headbolts. They're easier on the block threads because they will stretch a bit. Just amake sure they're in good shaper

[DanTreace]

Yes on re-using head bolts that check out in great shape, inspect threads carefully. Just be aware new reproduction of the dome nickel 26-27 style are modern thread type and a tad shorter in length.

If the block threads are super good, the repro work, if block threads at the grip range are poor, those shorter can spin out. Learned that. Salvaged that one hole by using longer store bought grade 5 bolt.

[Dodge]

Don't use a tap, it will remove precious material from the bolt hole. Instead use a thread chaser its meant for cleaning threads not removing
any material.

[RajoRacer]

Agreed - do not use any tap - this is what's needed to "clean out" the holes.

[Campbell Tellman]

Thanks to people with knowledge it makes this hobby more enjoyable and less frustrating.
Again thanks,
Campbell Tellman II
1916 Ford Touring
Beaufort, NC

[Jerry VanOoteghem]

Don't use a tap, it will remove precious material from the bolt hole. Instead use a thread chaser its meant for cleaning threads not removing
any material.

I don't mean to debate you and I do undertsand the reasoning behind this. What sticks in mind is that these threads were originally made with taps. If the threads are still in good condition, the only thing that another tap would remove is dirt. If the threads have been damaged, distorted or "pulled", a tap would cut away the distorted portion of the damaged thread, as you mentioned above. A thread chaser would tend to correct the distortion by pushing the threads back to their original form. However, my thought is that by that point, the damage has been done. The threads are in brittle cast iron and not in malleable metal that would be take to being "corrected" without fracturing. I can't see that either method would restore strength to an already comprimised thread. I'll admit that one method may be marginally better than the other, however. In the long run, I think both methods would only serve to allow the bolts to thread in easily and go to full depth.

The one plus I see with a bottoming tap is that you can sometimes thread the holes a bit deeper than they were originally to allow for a slightly longer bolt and few new, fresh threads.

As to re-using bolts, I would check each bolt by placing a thread pitch gage against the threads to see if the threads still conform to the gage, both in their form and in their pitch. The pitch may be elongated due to the bolts having been stretched. Checking the diameter of the threads may also help to indicate "necking". Areas of reduced diameter are due to the bolts having been stretched past their elastic limit. The next step for these bolts is failure, (i.e. a broken bolt).

[Dodge]

I should have given an explanation why a tap is not a good idea. It is because there are 4 or 5 different grades of tap tolerances.
The taps used in manufacturing are a tighter tolerance and it makes the bolt a tighter fit in the tapped hole.
The taps you get in a general set, the hardware store and off the tool trucks cut a deeper thread. This is done as most tapping done by
the average shop or home DIY don't use tapping fixtures and do it by hand. This lets the tap be a little off center/plumb with a bit of a loose
fit so everything goes together.
So using one of those general set taps removes material in engine block holes which gives less holding power.

[Jerry VanOoteghem]

I guess it comes down to not using cheap taps.

[DanTreace]

Forget the tap dance

Old timer mechanics just used a screwdriver to stir debris deep in the bolt hole, and remove that metallic stuff with a Ford magnet against the shank.