The Stovebolt Site Forums The Shop Area Engine Shop New rebuilt engine w/xtra hole in block!

So I had my 292 rebuilt by a decently well known builder who is out of state and when getting ready to install the water pump I noticed it had an extra hole in the block. I contacted the builder and sent him the picture he said someone must gave drilled a hole in it for a 250 water pump and he missed it. Now he takes engines in as a core so you don’t get your exact block and I was ok with that untill this!

This guy is prominent member in the inline motor community and everyone on the various inline groups tend to rave about his work , service and knowledge.he is constantly busy so I waited almost a year to get the build done. Anyways after paying a very large sum of money for the engine it has this extra hole! So I contact him and he says it must have slipped by, ya think! He now wants me to get a pipe tap to thread the hole and install a plug. He is out of state so I can’t just drop it off it would need to be shipped. So I have never tapped anything before but am relatively decent with my hands.what are your thoughts on this being an acceptable repair for a newbie?

Based on principle and what it cost me I tend to think it should be replaced but when I think it is not much different than a freeze plug it isn’t that terrible.

Thanks,
Eric

Depending on the thickness of the casting, that should work OK. If it is too large to fit in a drill press or milling machine, important thing is to get the tap vertical and use a brass plug. Search around and get the plug first, they make them with recessed six point or raised six point. Raised 4 point would be a poor choice.

Make a small fixture to hold the tap vertical to the surface. Get tap OD from the smooth(upper) surface, make a small block with hole size of the tap and bolt it down with the adjacent threaded hole. Aluminum or even some hard wood would be fine. Use some tapping fluid and check it frequently with your plug. Use some setting thread material after cleaning with acetone to remove all vestiges of tapping oil. Put some grease in the tap grooves to catch filings.

Ed

Cast iron is self lubricating so, no threading fluid is needed. I would also place a magnet on the top end of the tap, to help collect the cast Iron shavings and vacuum out the cavity after tapping.

Tap it so you can turn it in 2-3 turns by hand, then use a pipe sealant and install the plug.

EDIT: added the word no! Thanks klhanson!

Why not just use a 250 water pump?
If you do use a pipe tap, I would use a brass plug with the square head raised above the plug, seat the plug in the block with high strength lock-tite, then grind the plug smooth to the block. It would never show this way.

While the situation isn't ideal, given the so-called "professional" reputation of the rebuilder, it also sounds like you're turning a minor annoyance into a tempest in a teacup. There are probably dozens, if not hundreds of mechanics and/or machinists in your area who would be willing to spend 15 minutes plugging that hole if you're not confident in your own abilities. I wouldn't even bother threading the hole- - - -I'd just turn an aluminum or brass plug a few thousandths larger then the diameter of the hole, drive it in with a hammer and a punch, and draw file it flush with the top of the block. If there isn't a corresponding hole in the cylinder head or the head gasket, leaving the hole open shouldn't be a problem.
Jerry

Jerry, the hole is in the front of the block where the water pump bolts to.

OOPS! I had the impression the hole was under the head gasket. 5 minutes with a pipe tap will solve the problem- - - -no reason to get whiny about it!
Jerry

To correct Phil's typo NO lubricant is needed for tapping cast iron.
Looks like you have access to the back side as well so stick a magnet just below the hole while you're tapping to catch the chips. Getting it perpendicular to the surface isn't even a big deal if you're just plugging the hole, and a cast iron plug would be best to match the expansion/contraction of the base material. If you grind it off flush it would even be mostly invisible once the block is painted. Use some pipe dope or some Permatex #2 on the plug when threading it in and just get it snug.

Thanks Kevin for watching my back!

If you are not confident doing it I would take it somewhere and send him the bill. Call him and see if he is OK with that. For people that do that stuff it is no big deal but sometimes what seems easy to some is scary to others.

What is the end use for the 292? Unless you're going to be doing "truck stuff" (hauling heavy loads in very hot weather) the simplest solution might be to run a 250 water pump. The 292 has a somewhat different thermostat bypass system to avoid hot spots developing around the front of the block under heavy load conditions. 250's are a bit problematic concerning coolant flow around the #1 cylinder for some reason.
Jerry