Removing snapped bolts

**Aaronhl** · 05-15-2023, 10:55 AM

Also wondering if I can interchange the casting numbers, ebay looks like they have more of the older heads, not the newer casting number that the 2001 block serial number calls for ??

**derekfl** · 05-15-2023, 12:12 PM

grainger stainless thread inserts. m8 bu 1.25 the outside is a 1/2-13 standard coarse thread. so hold a 1/2 inch bolt up to the bigger holes and see if it will fill the hole and also be small enough to have meat and thread all the way around. also contact lock n stitch. they may have better options for filling in around the bolt. put a head on and use a drill guide to re-center the orig bolt hole. then you may want to just do 7/16ths of 1/2 bolts instead of 1.25 or 5/16 or 3/8. whatever fills each hole best. cuz it may be easier to re-thread the actual head bolt threads after the repair if you are not cutting right where another thread is. then think about studs instead of bolts so the torqueing down is done on threads that are not turning against the new patch...

**Aaronhl** · 05-15-2023, 12:21 PM

it's helpful to get u guys to mention about the different type of threaded inserts - the issue is that the block actually need some area filled, from the over drilling going into the head-oring section and the welding mess, the head face of the block need a little work around those bolt holes, maybe if i can fill it and the threads still suck I can use a threaded insert from there ......

**OnPad** · 05-15-2023, 12:44 PM

Weld around bolt in order maintain original threads. Idea being, you don't have a cross threaded mess in the bottom of the hole, I get it. I know of no tap, that cuts from the bottom up?
Try one and see how it turns out, but I like Chaz's idea of starting over with a tig.

I think your heads are backwards compatable, but idk alot about 3L. I know some in the early years had crap for compression.

**Chaz** · 05-17-2023, 09:52 PM

Forget about the threads at the bottom. They have dirt, salt, oil, glue, polly-raz-a'ma'taz embedded in the metal.
Start with a clean slate, bore down to clean metal .. then out the side. A good welder can play Mr. Dairy Queen and swirl fresh filler rod to the top and out the side. A little sanding roll action and you can't tell where it was fixed. It will need to be decked, get over it, it's not a big deal. A few thou, and it's flat. Run your fingernail across the register (alum) and sleeve ... anywhere on the deck, it's not flat by a long shot.
Look at the heads and deck real close on any of em .. you can see where compression leaks out, water seeps in .. they all do it eventually. Buy a cheap set of transfer punch's bolt a head on ... thuclunk the proper size punch. Drill and tap your brand new 8 x 1.25 mm hole ... and never look back ..

Every set of early model 300pm or late 300x heads I had ... sold in 5 minutes.

Std. bore to .044 over .. I use 225/250 clipped to what the ex. port ht. dictates.

3400/3600 cc big bore stuff, you have to use billets.

For guys running early blocks , you can use late style heads. You just have to "fix" them to accept the early water temp sender and plug the late model hole.

There was a year or two during transition, where they cast the late thermostat housing pad , then machined them as early models.
I've done a bunch of sets where I drilled the hole 1.000" for the late, hi-flowing stainless stats .. and drilled , tapped for the late stat covers. That lets you run the large diam dump hoses. You also get to mill down the bosses for the long head bolts, now all bolts are the same length .. Personally, I would never do a motor with those four long bolts (two on each head) , unless I absolutely had too ..

**Aaronhl** · 05-19-2023, 12:40 PM

I ground out the dirtyness of the largest hole and went at it with the spool gun - I am not good at welding aluminum - but went for it anyway...Seems like it was more or less balling up instead of puddling so well see how the weld areas stick when I get it threaded, maybe i will need to add an insert or helicoil, seems like the weld atleast gives me more meat to work with and I have a surface for the o-ring - shame on me I used my 150/220 grit sanding block to "mill" the bubble down

5 more holes to do before threading what do you think ??

**derekfl** · 05-19-2023, 04:52 PM

looks like a decent job. a large flat file will also work to flatten the surface. the iron sleeves will keep the file honest.

**OnPad** · 05-19-2023, 05:00 PM

Make sure everything is super clean, apply some preheat before you weld.

**Aaronhl** · 05-19-2023, 05:13 PM

Thanks guys, I used a dremel because the 1/4 bit on have on my air grinder jumps all over the place, I was able to grind to clean surface in the hole before welding, i ground the threads down, hopefully the welds had enough penetration so as I drill the M8 again there is enough material for the threads, might need to step up on a larger diameter insert, again atleast i was able to fill area for the head oring, it def got easier to weld as i got closer to the top, i was using a propane torch to heat as much as i could i dont have oxy

**H2OPERF** · 05-19-2023, 11:11 PM

I know its too late but next time you may want to pick up a drill bushing slotted base and a pilot hole bushing, we used these on aircraft stuff all the time to get a straight hole. i have used my set many times on outboards to get a good pilot hole when drilling out a bolt for a helicoil. This is a pic of the base you bolt down with an adjacent fastener then you put a hardened insert to what ever size you want to drill on your first step. There are tons of bushing sizes on ebay really cheap

**derekfl** · 05-20-2023, 07:52 AM

i think you can also get a bushing that fits head bolt hole and use a cyl head with bushing in it the same way. i think i already said it, but use a drill press, not a black and decker bolt hole wrecker...

**Chaz** · 05-20-2023, 08:54 AM

Only you know what you saw as you were welding the hole shut. The wire either became part of the block ... or ... just made a ball at the bottom of the hole.

Gotz old BBQ grill .. they make a great block and heads .. pre-heat tool ..

**Aaronhl** · 05-20-2023, 10:49 AM

Originally Posted by H2OPERF

I know its too late but next time you may want to pick up a drill bushing slotted base and a pilot hole bushing, we used these on aircraft stuff all the time to get a straight hole. i have used my set many times on outboards to get a good pilot hole when drilling out a bolt for a helicoil. This is a pic of the base you bolt down with an adjacent fastener then you put a hardened insert to what ever size you want to drill on your first step. There are tons of bushing sizes on ebay really cheap

no not too late at all- I think that exactly what I need to drill the holes, they seem hard to find

i hope I’m keeping you guys entertained !!!

I use a dewalt drill not B&D

pretty sure I got the wire to ball up down low !!!

plan on drilling holes to see how much meat is down there, then putting a 1/2 threaded plug if needed, re weld on top of the plug…before taping again to m8

**Aaronhl** · 05-20-2023, 12:56 PM

Was easier to grab the block when I got closer to the top, you can see in one pic I have have some pebbles

**Aaronhl** · 05-20-2023, 08:56 PM

Trying to finish this with the limited capability I have, Drilled the 5 -.270 holes 1-3/8" deep for threading, mainly to register each of the 5 holes and see how the insides look, some insides look better than others, hopefully I will have enough there to cut into to without stripping M8 bolts, will step up to thread repairs, inserts or a filler plug if needed, atleast I have the holes registered pretty accurately, I could feel the drill as I got lower in the holes line up with the original

Glad I had a junk head to use with untouched holes, used some brass tubing to make bushings and it was very easy to drill the holes with my Dewalt "handheld drill press" and took out the "3M" depth gauge (Chaz approved??????),,,,, let me know what you think

Ill get back to let you know how the threads hold up on the 5 on the starboard side, was able to fix the 6th hole on the port side, it was a simple fill and sand down on the deck, no thread repairs needed