Minor crack on SBC cast iron block

[Al Weyman]

I had this happen at the weekend I am a bit peed off to say the least. At the back of the SB Chevy engine are three screw in plugs that have to be removed to clean out years of sludge that builds up in there. Well they have a stupid 1/4 square slotted hole to get them out which invariably rounds off or snaps the socket which happened here so I went on the net and some bright spark had stuck up a YouTube vid saying drill them out and use an easyout. I tried this and got one out then ping this happens. Gutted especially as I had just picked it up from the machine shop after having it bored!

I was thinking of using a bit of JB Weld in there but not happy about it as although its a none stressed area at the end of extremities of the block if JB fails as these plug up the oil gallery and will be under pressure (80psi aprox) it will pump oil out all over the clutch and make a right mess. Apperently its not uncommon and a US site I go on one of the top car and engine fabricators told me he did the same on a Dart block so I didnt feel quite so bad or stupid, he also told me the best course of action is to weld or braze it up and also weld/braze the fitting in there. I have ordered a 1/4 18 NPT tap and will drill the rest out and retap them then think about trying to get this repaired, any constructive comments guys?

[BertMk2]

Welding or brazing would seem the obvious (and already suggested) answer - saw something similar done on a vauxhall lump and that did the job.

[GORDON STREETER]

Easy outs are one of the worst things ever to be made (the tapered type) as invariably they sod the part up because they just expand the part and make it worse, they also snap off and as they are very hard you cant drill them out.
The best ones are the parallel ones with side flutes using a dedicated drill size.
The thing is if it can't be undone by however it's supposed to be, a smaller diameter insert is unlikely to do it either.
I know this doesn't help you at the moment Al but the best way to get out a broken flush stud IMHO is to MiG weld a thick washer on top of the stud through the center then weld a nut on the washer.
The heat normally frees up the thread and you then just undo it with the nut.
Been doing it for years and very rarely failed.

[Colin McKay]

Al, I used these people http://www.metalock.co.uk/Typical_On...n_Repairs.aspx to carry out a stitch repair to a 9" crack on a Mack block many years ago. It's not cheap but lasted for years on a hard working truck engine. I remember seeing vintage Rolls & Bentley blocks in for the same treatment.

I understand that the problem with weld repairs (you probably know this) is the amount of oil in cast iron which makes a good bond almost impossible.

[Al Weyman]

Yeah someone else said about that as well, I want to get a couple out at the front of the block as well but not sure I will bother now.

[jhh911]

As long as its clean if you Jb weld a fitting in I would be amazed if it comes out. I doubt you will braze it unless the whole block is heated to a very high temperature.We bought a Junior Johnson Nascar motor and he had JB welded the inlet manifold on.That came as a shock when we tried to remove it!

[Al Weyman]

The thing I am worried about is the crack will go through to the pressurised oil gallery so that has to be sealed correctly however its done.

[Cameron Winton]

It might worth drilling a stop hole at the end of the crack. That will stop it propagating further. Would do this even if was being built back up with weld as the weld material will have a different crystalline structure. Never used it but many people swear by JB weld.

[GORDON STREETER]

Originally Posted by Cameron Winton

Never used it but many people swear by JB weld.

I know someone that raced a Mini where the rear subframe was held in at the front by the bolts that were screwed into tapped threads in JB weld !
Lasted a season with no problem

[Al Weyman]

The trouble with this is it goes into an oil galley if not it would be simple to elongate the threads in the hole past the end of the crack and screw in a longer bolt but this would block the oil feed hole to the camshaft I have recut the thread and have thought about running a threaded pipe deep into the hole and then drilling out the oil hole and putting a solid bung up behind it but before I do that a mate is going to have a go with Tig and some high nickel filler rod I have bought. I am going to let him practise on an old block in the same area first and see what happens. I will post back the results.

[The Shrew]

Ive seen quite a few welded blocks in my time in a few different places and all have lasted well. The difference is the ones ive seen have been truck engines not racing engines.

Id say it would defo be worth a shot it only looks a small ish crack. Ive seen 5'' square plates welded to the side of blocks in the past.

All the best whatever you decide to do

[Al Weyman]

Triucks probably take as much if not more abuse than my race engines, my mate has had a look at it and recons he can do it, will know Sunday so fingers crossed.

[Al Weyman]

The guys know what they are doing and preheated the area to 100 degrees before TIG welding with Nickel filler rod, well pleased. They checked it first with crack tester dye and saw it was worse than I first though with a crack at 1 o'clock as well as the one that was obvious which had actually 'Y'ed out under close inspection.

[Al Weyman]

Pleased to report after two 20 minute duration races and a 20 minute qually the engine was bone dry with very good oil pressure and running at no more than 70c water and oil temps. A successful repair!

[The Shrew]

Still going strong Al ?

[Al Weyman]

Yep no problems at all, two races at Speedfest and a qually and probably the dryiest SBC engine I have built to date!

[The Shrew]

Nicely, cant beat a bit of old fixing rather than fit new