I am in the process of disassembling and cleaning my 52 8RT engine prior to rebuilding it. As you can imagine the 60 year buildup of gunk and dirt is fairly substantial.
This evening I removed the heads and intake manifold and only managed to snap one headbolt I was able to remove the broken bolt without too much difficulty and no damage to the block.
I also cleaned up the bolt holes in the block with the appropriate tap. then I went online to look for replacement bolts.
During the course of my search I came across an item on another forum (which will remain nameless) which indicated that you should NOT clean the threads in the block with a tap as they are tapered and the new bolts will not fit/seal properly!
Could someone please clarify this bit of info, and tell me please that I have not buggered a perfectly good block?

 

I've probably built 10 flatheads through the years including a supercharged version. This has been advice given all through that time. Some follow it some don't. Blocks have been fixed with Heli-Coils so it shouldn't matter. I think the original blocks did have a bit of interference fit on the studs but I've used a tap to clean up the threads many times with no adverse results. Be sure and use a generous amount of sealer on the threads and re -torque after the initial fire -up (cold). Re-torque after a couple hundred miles and every 500 miles after that. Having said all that, I'll really make your day by saying that the first bock you test is often a leaker anyway. Some guys go through 2-3 blocks until they find a "good one". Don't spend too much time on it until you have it magnafluxed.

 

Can you PM a link to that site? It is correct that you should never (on any engine) use a thread cutting tap to clean an existing hole, because it will make it sloppy. There are thread chasing taps made for cleaning old holes. But I have never heard of flathead deck holes being tapered. They are notorious leakers, particularly on the 59-series engines with studs and nuts on the heads. How to seal them is a frequent subject on the Flathead Forum. GM thread sealant #012346004 is one of the best but is $20 for a 50cc bottle.

 

Albuq is correct. Chasing the deck holes is the safest procedure and necessary for good torque readout. In my mind the stud holes are not the key items for leaks, block cracks are.These things can even have cracks down the pan rails! Bottom line, if it passes the crack check, use it. Last bit of advice, you simply can't see all the cracks with the naked eye. You really should have it chemically cleaned and mag checked. Good luck.

 

Thanks for the replies,
Hopefully I haven't messed things too badly.
I will be having the block cleaned and magnafluxed before I proceed with the rebuild, just to be on the safe side.

One more question, this engine, and my spare engine (a 53 RT) both originally came with headbolts as opposed to studs and nuts. Most of the replacement kits I can find online contain studs and nuts. Does this make any difference? Can I use studs and nuts, or should I stick with bolts?

 

Some say you get a more accurate torque and seal with the studs,but I would just use the bolts with good hardened washers underneath if I were you since that was how it came originally. Just use new bolts as they can distort after multiple torqings. The studs make the heads harder to remove if you ever have to do so again.

 

Get your engine into the machine shop before you start worrying about anything else .

 

LOL! I think this is what you meant to say!!

 

Not really but it could save from spending money on a non repairable engine .

 

I never heard about the taboo on cleaning the threads with a tap, I just happen to do to a flattie the other day, I hope I also didn't screw anything up.

 

I never pretend to know-it-all. I have learned something, here, I never heard of.
Thread cutting tap and thread chasing tap? Thats a new one on me! Ok gotta go...got some research to do.

 

JEGS Thread Chasing Tap Set - JEGS

 

The bolts are really nice bolts. They end up in a lot of places like into my sm 465 tranny through the crossmember in my fridge truck. Must have been tough snapping one off. Glad you got it out. A flush to the deck snap can be a tough proposition....

 

I have a spare set of head holts if you planned to replace all of them .
I went with aluminum heads so I switched to studs .You or anyone else can have them for the cost of shipping .

 

PM sent..................