steel bolts on flathead heads

I'm refreshing a running Merc Flathead & pulled the heads off. all the bolts came out on the heads. I don't really plan on putting aluminum heads on yet.

So the question is, is it better to put the same bolts back in or use new bolts or use studs.

Thanx in advance

 

Since bolts are relatively cheap, I'd replace them. Consider it cheap insurance against potential future drilling and tapping, especially if you don't know how long they have been in there and what quality they were.

 

I went the AARP head bolts route on my flathead. I ordered the length I needed for the alum. heads I used. Not cheap, but I have had zero problems with them.

 

I bought a set of grade 8 bolts, plus grade 8 extra heavy washers. Work out very well

 

If the bolts are in good shape, I wouldn't worry about re-using them. But, examine the ends of them carefully, many times the tips of the bolts are eroded as they sit in the water jacket. If they look like new, just clean the threads with a chaser, oil them up and drop them back in. There's relatively low tension on them for a head bolt so they generally aren't stretched or stripped but the erosion on the ends is common.

If you switch to aluminum head, you will definitely want to run a washer under each bolt to protect the head from being galled by the head of the bolt. Various flathead parts suppliers sell the washer kits...

 

Clean the bolt holes with a thread cleaner, not a tap. Wire wheel the bolts and inspect them, if they are OK, oil them well, and reuse them. I torqued mine to 55, about four times. If you buy new, you will have to shorten them. There are some that bottom in the holes, and many go into a water jacket. They all need sealer.

 

Henry's original bolts are better than grade 8, use them as many times as you want. Never seen one fail yet. Any aftermarket bolt kits are for aluminum heads, some are too long for iron heads, as mentioned above.

 

So if my original head bolts are in good shape, is it better to keep them or go studs?

 

Keep them.

 

AARP bolts for Senior engines!

 

I recall I was reusing my original OEM FORD headbolts on my flatty and torquing them to 55 foot pounds on alum heads when suddenly the bolt head turn too easily and felt "soft". I was able to back it out without breaking and could actually see where it was starting to "neck down."

 

Use a water type sealant like Permatex #2 on the threads when installing the head bolts. It'll help keep them from seeping.

 

Saw a flattie with Ace Hardware stainless bolts....