Well, shoot! The slant in my T-bucket has developed an external crack in the block, right about number 5 cylinder, on the starter side and is oozing coolant. I've checked with a couple welding shops around, and they've given me, at best, a 50/50 chance that welding it would be successful without creating fresh cracks. I don't like those odds for the trouble, sooo, it looks like I'll need to start building a new motor.
A friend has suggested I attempt to gouge out the crack and slather in some JB Weld. I'm inclined to give it a try, but also realize that it'll only buy me some time. That crack will most likely continue to grow.

Care to offer some input?

I have; A 225 short block that's been open for a long time, with rust on the cylinder walls. I think it'll clean up at .060, but haven't measured it.
A second 225 in my unfinished Mitsu Chally that did run a few years ago, but has been sitting untouched and on a back burner.
A 198 complete engine on a dolly that's was running poorly when I got it,. condition unknown
An '80(?) 225 short block and matching head, but I'm not too enthralled about using it. (This was a free-bee.)

Parts; A set of vintage, NIB, L2125-.030 TRW pistons, but no matching rings
A set of NIB 2.2L 4-banger pistons, (dished tops, no matching rings)
A NIB double roller timing set
A NIB E470621 Erson grind cam
A NIB TQ20M/30M Erson grind cam
A NIB set of Erson lifters
A full set of oversized valves, (bought in a group buy years ago.)
Two single-four intakes, one Clifford, one Offy, without adapter plates. (I can make one of those.)
An Offy twin-1 bbl intake, and plenty of Holley 1904 cores to rebuild. (This is the induction I would MUCH prefer, with the glass bowls.)
The makings of an electronic ignition system, either aftermarket or an HEI conversion.
Quite a few oil pumps with original gears
I think I noticed a NIB water pump in my stash, too.

Use: In a 904-equipped, 2000-lbs. street T-bucket. No frills, 3:08 rear gear, open-engined hot rod. Just would like a nice, warmed-up street motor with some reliability. Currently, it settles into a nice, comfortable "groove" right between 60-65 mph, AT 2300 rpm. A nice speed for road-trip cruising, so no major driveline changes are in the plans.

So.....you can see I have a couple options. I'm leaning toward a (mostly) stock rebuild with the L2125's (I hope), decked .050 on both head and block, stuff the TQ20M/30M cam in with the oversized valves in the head. Some port cleanup, with intake-to-head matching, an HEI conversion and run it till the wheels fall off.

Still open to suggestions from the more knowledgeable builders here, so sound off, boys.

Roger

P.S.; Has anybody found out any more info on that possibility of using those other import pistons that was talked about in this thread?
https://www.slantsix.org/forum/viewtopic.php?t=68217

Are you certain you want to replace the original? Other than the crack are you happy with the current engine?

Drill a hole at the ends of the crack and tap the hole for a plug. Then slather the crack or try to weld it. Uncle tony's garage on Youtube did a video on repairing a block with a cheapo flux core welder a few years back. I believe he was repairing a 413 and I don't recall if it went into a coolant passage.

How close is the crack to the freeze plugs? 3 hole/5 hole block? If it is the 5 core plug block I would also consider a coating on the inside of the water jacket. Run a good cooling system cleaner, used to come from tractor/farm supply companies. Then flush with water repeatedly and drain system fully including the passenger side block drain. After draining, pop out the core plugs and blow it out with air. This would give you a good starting point to get a sealer to adhere to the inside of the block.

At least you have a high side issue, it is so much easier to access stuff on the left once you get everything out of the way.

plus one for repair it.

yes drill both ends of the crack and v it out
then weld or braize it up.
the key to cast is pre heat it and keep it warm while welding/braizing and then letting it cool slowly and evenly.

there are good options for rods for cast iron welding.
i prefer brass because less heat is needed.

also plus one for using that offy twin 1bbl intake.

It won't hurt to try and fix.
If you're happy with it as it runs now, id probably take the guts out of that block as they are and put them into a different block. New gaskets, rings and bearings for sure/and bore out the new block if needed to match the pistons you would be swapping over...

What type of build do you presently have in the T bucket, and how do you want the new one to improve upon that?


I might be inclined to consider a block sealant for driving it this for now this summer. Or do some welding on the block to stop the crack from spreading and then..... I put some Barrs radiator stop leak in a 09 highlander that had a water pump leaking... because I had NO good options for repair unless absolutely necessary last winter.

To be fair it will leak just a little during warmup on the -5*f days of a cold start, but it has effectively put off the actual repair for over 15K, and gotten me out of that mid winter jam.. sometime this summer/fall I will get to it... but above freezing it doesn't leak at all.. I can't believe it, but for seeing it with my own eyes!

Better than welding. I used this system back in the '70's and '80's. Worked realy good.
https://www.locknstitch.com/index.html
https://www.youtube.com/watch?v=kHS1NtC4tAA

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I would try repair, AND start building your new motor. Personally, I would probably try drilling/plugging on either end then JB Weld a clean and Vee-d crack, or get even better epoxy.

I like your basic engine recipe. Please post both cam specs when you can. Likely shoot for 9.5:1, which should be reasonably close with 0.050" off each of block and head. Need to measure though.

I LOVE building Slant motors...

Lou

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Home of Slant6-powered fun machines since 1988

the only problem i have with this is repetitive expansion and contraction with any glue will fail quicker than welding or brazing.
i have also recently started mig brazing for body work which would probably be the ideal for this situation. though i haven't worked with it enough yet to say for sure.
mig brazing does require a bottle of straight argon and the correct wire.
i was very impressed with first tests and replacing the spare tire well in my nephew's csx(which was to date my first and only use of the process)

I took 0.100 off total between block and head on my last build (0.030 block, 0.070 head) and I ended up measuring out exactly 8.4:1 which is exactly"blueprint", stock spec.

Find the ends—the very ends—of the crack and drill holes to stop the crack propagating further.

Properly prep the crack for repair (grind it to a vee shape, etc)

Swap out the JB Weld for an appropriate grade of Belzona see here and here, and ping the manufacturer for guidance on which grade to use and how to prep and apply.

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Too many people who were born on third base actually believe they've hit a triple.

It's a bone stock, (about) 1974, 225. I got lucky some years back and picked it up from a smaller community high school shop class that was clearing out their excess. Had a fresh rebuild on it, as it was a core used by the students. It still runs pretty darn good, and I don't really need to replace it except for the leaking crack.
I just figure that if I really have to, then I might as well make use of the parts that have been languishing in a cabinet.

I like the idea of crack repair, but my local (2) welders are telling me the odds are not in my favor. So, it looks like my best bet may just be a cold fill repair.
I considered the stop-leak approach, and have used one in the past during a road trip for a rock ding on a cooling tube on my old radiator. It did work, but I just don't have a great deal of confidence in such band-aids.

Roger

Sorry, all......this is the direction I'm headed. A solid cold repair, and a rebuild that I don't have to rush. (Machine shops around here are a little thin in numbers, and the stock car guys keep them hopping, so the wait times can be long.)
Thanks, Lou. I figured the measuring part was obvious. I think I have an old Fel-Pro "permatorque" head gasket, but I'll have to confirm that and measure it when that event gets close.
I just might have a local shop do a head rebuild first, in prep for the short block. I can probably get that machine work done quicker than a bore and deck to a block.

Roger
Thanks a bunch for this, Dan. JB has a good rep for their product, but if I can score something even better/more reliable, it's a no-brainer to me.

And to all that recommended the cold repair tips, a hearty thank you.

Roger

I also think welding/brazing, especially on a block still in a car w/no disassembly, will be a total crap shoot. I was hoping Dan would bring up the Belzona, since I forgot its name, and of course he did!

Roger, if you can, take your crank and a stock rod and piston (sans rings), but 2-3 old main bearings in and an old rod bearing on that rod. Put those in the block and get a TDC measurement. That will help you plan the build. I've done this before. Let me know if you need a stock used crank+rod and/or used stock bearings. I have a few laying around. Once you have TDC, you can plan how much to mill off. I'd take 0.100" off the block and take the rest off the head. If you need to swap heads later (much easier), then you'll have most of your CR gain built into the block.

Best to get the valve seats enlarged for the new valves and the head degreased, then do your porting yourself with air die grinder and carbide burrs, then take it back to the machine shop for valve job and final assembly. You can gain a LOT of flow/power without a lot of porting. Focus on the bowls and don't go crazy with it.

Have fun!
Lou

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Home of Slant6-powered fun machines since 1988

Yup. Just be careful when porting. I went as far as I dared on mine and the machine shop "touched it up" when I took it for the prep for the OS valves and rest of the valve job

OK, Dan.......inquiry sent to Belzona, now awaiting response. I see "my" nearest distributor is a fair bit north of me up in Minnesota, so that'll be a mail-order purchase.

And Lou......you wanted to see the cam specs. I'll need to get back to this thread on that....."film at 11:00".

Roger