Okay I received a pack of new "low" headbolts this week and went to test them with the head on without a gasket and they are too long. The measurement from the bottom of the head to end is 2.5". They are hardened based on the markings on the heads- can I possibly find these bolts at a hardware retailer?
Perhaps my head was machined down at some point? Not sure, no history on it. (pics attached)
What do you fellers think?
According to Langs catalogue the 3 1/4" bolts are for the later high head engines.
2 3/4" bolts are for the low heads.
Who ever you ordered the bolts from sent you the wrong bolts. Call them for replacements.
One more thing to remember James is to clean out the bolt holes. You will be surprised how much rust and corrosion is in the bottom of the holes.
Use compressed air and a ice pick to clean the holes or something similar then use a bottom tap to clean them up to the bottom.
The 2 3/4" bolts should go in without much trouble.
Got it, thanks John.
Did you try them? The original bolts I do not think have any markings on them. If after cleaning out the bolt holes in the block they are still too long, add spacer washers under them.
His old bolts are 2 1/2 and the new ones are 2 3/4. The ones sent should be the correct bolts.
If some material was taken off the head, that could be why the shorter bolts were installed or there is a lot of crud in the bottom of the hole and to get the head to seal shorter bolts were used.
Yes you could buy off the shelf 2 1/2 inch bolts.
Other way to go; clean the threads with a die and wire wheel the rest of the shank and reuse.
James, I would use a bottoming tap to clean out the holes in the block first. Then I would run the bolts down in the holes to check that I had good depth of thread engaged.
With the head in place, with no gasket, I would fit all the bolts and then note how much has to be cut off the one sitting highest. A hacksaw will do the job. That way you have an even length set of bolts with maximum thread engagement. As a cosmetic finish, I would grind off the markings on the bolt heads.
Hope this helps.
Allan from down under.
A drill smaller then the hole run at slow speeds or even twisted by hand does wonders in breaking up the crud at the bottom. Don't push on it if you use a drill motor. Vacuum it out before you run the bottom tap in then again after.
I agree with Allan. Use a bottoming tap and then a shop vac to suck up any dirt, rust, of metal filings.
James, your "original" bolt is a common grade 5 hardware type bolt. You are correct that it is hardened, "some". They may have been installed for a reason, or just because they were "handy". I would guess the latter. Dave
Forgot to add, looks like you need to do some research on what you have and what you need. Dave