Screw in Freeze plugs. 351 Cleveland

[Charrlie]

Screw in freeze plugs for 351 Cleveland.

Surely someone has attempted this when rebuilding a motor.  Looking for any tips.

Charrlie

 

[Bentworker]

Never tapped a freeze plug.

However I have tapped a lot of other things...

CASTROL VARIOCUT C MOLY-DEE TAPPING FLUID

The stuff is magic. Also buy a decent tap / taps. McMaster-Carr is a good source, but not always the cheapest.

I'd be tempted to use a tapered reamer to cut the hole before tapping it. http://www.victornet.com/category/NPT-Pipe-Reamers/802.html

Looks like you could wrap 100-200 dollars in a couple npt taps and a reamer, along with plugs.

 

[6972boss]

Never tapped a freeze plug.

However I have tapped a lot of other things...  

CASTROL VARIOCUT C MOLY-DEE TAPPING FLUID

The stuff is magic.  Also buy a decent tap / taps.  McMaster-Carr is a good source, but not always the cheapest.  

I'd be tempted to use a tapered reamer to cut the hole before tapping it.   http://www.victornet.com/category/NPT-Pipe-Reamers/802.html

Looks like you could wrap 100-200 dollars in a couple npt taps and a reamer, along with plugs.

I have had a machine shop tap a 4 bolt main for screw in freeze plugs. Worked perfectly. I have an extra set if you need. 

Robert

 

[kcmash]

With our classic Cleveland blocks, what is the benefit of screw in plugs?  I would rather use the factory protection method and let thos suckers blow out to save my engine!

But then I don't know the real driver behind screw in freeze plugs, so feel free to educate me.

kcmash

 

[Bentworker]

Pretty sure the benefits of the screw plugs are two things.

1) They look cool.

2) You never ever loose a freeze plug. Think of it like a safety thing. If you are at the drag strip or at a track event and your engine was to spew all of it's coolant out you would loose traction as soon as your rear wheels went over it. Best case you could recover safely, worst case you could wreck your car. Not saying pushing out a freeze plug is common, but I could see how it would be a bad day.

 

[Charrlie]

Pretty sure the benefits of the screw plugs are two things.

1) They look cool.

2) You never ever loose a freeze plug.  Think of it like a safety thing.  If you are at the drag strip or at a track event and your engine was to spew all of it's coolant out you would loose traction as soon as your rear wheels went over it.  Best case you could recover safely, worst case you could wreck your car.  Not saying pushing out a freeze plug is common, but I could see how it would be a bad day.

 

[Charrlie]

Thanks for the replies on the threaded freeze plugs. Most of us agree it seems that if you blew a push in you may lose a motor

before you figured out the cause. Charrlie

 

[Jeff73Mach1]

Freeze plug is a misnomer. It is not their purpose to push out in case of a freeze except in some marine applications . . . perhaps.

They are core plugs.

In the casting process there is a sand form for the water passages and the hole is for the removal of that sand, post casting.

Screw in plugs look cool, that is the best reason to use them. They are more substantial and less prone to corrosion eating through them-but the ease of unscrewing and reseating it in a confined space might be the biggest advantage.

 

[Stanglover]

Totally agree with Jeff. Freeze or frost plugs as I know them, is totally a wrong description. There purpose is to allow for the removal of the core sand and that's it. My guess is that at times when blocks have frozen, the plugs being the weakest point, would probably pop out.......... or not! I recently scrapped a block I bought that had been frost cracked and welded and was not worth salvaging. Wish I'd seen that before I bought it!

So if you never have to worry about freezing up a block, well go for it.

 

[jpaz]

If you stay with the normal casting plugs make sure they are good quality steel or better yet brass. Don't use cheap Chinese crap like the PO did on my engine. I’ve had to replace 2 of them and what a pain! At least so far the ones that were bad I was able to do in the car, but I’m sure sooner or later I’ll have to lift or pull motor to replace the rest.

 

[Don C]

I've seen a few blocks that had been damaged by water freezing in them, none had been saved by the "freeze" plugs popping out. The most common place where the blocks cracked were at the plug locations, as that is a weak point.

 

[Carolina_Mountain_Mustangs]

The core plugs can blow out that is why the NASCAR blocks and Boss blocks had screw in plugs. I believe Australian blocks did also. If you notice in the heads there are screw in plugs under the valve covers.

They do rust out for sure and you pretty much have to pull engine to do a good job replacing and if I remember right one behind flywheel or flex plate.

In the race shop before they had the screw in plugs we would drill small holes adjacent to the plug and put like three drive screws in to help hold them in.

I was at Charlotte swap meet yesterday and there was a boss 302 car that had a frozen and cracked block. It cracked in front of the block on the R.H. bank just below the head. The owner said he had not seen the crack. That scrap block dropped the cars value by many thousands of $ not numbers matching. You can braze a crack we use to all the time and there are some great welding rods made today for welding cast iron. I would not scrap a cracked block unless it was really bad. That would be like scraping a body because of a rust hole, lol. Hey the whole block was molten at one time. Space ships have welded in components. Don't be afraid of it.

We would have massive stamping die failures and would send the tools to MPD Welding in Michigan for weld and braze repairs. They would use big heat tables to preheat the casting and grind out Vee and use like 1/2" diameter brazing rods and braze 24 hours 7 days a week to put a crashed die back together. It is a very common practice so do not toss a cracked block or head. Check with them if you need a casting repaired before tossing it. I have seen tools welded that weighed over 30,000 lbs. cast iron several inches thick. They ran for years after repair under heavy stress stamping parts.

David

 

[Stanglover]

David, Don, I get your point about cracked blocks and repairing. In my post, I said I scrapped the block, when in actuality, I should have said I didn't want to spend the 400 bucks Cdn to have it pressure tested and magna fluxed. As I did not need that block anymore, I gave it to a young lad who may build a motor with it for his Bronco.

So, it may still live!

Geoff.

 

[EBSTANG]

A friend of mine and I had both our Cleveland blocks machined for a one-piece rear main seal and I had mine tapped for 1 1/4" NPT Ford Racing freeze plugs. It only cost about $150. The RMS machining cost about the same. Why not? I had a brass plug blow on the dyno once...

 

[Jeff73Mach1]

If I could find someone local to machine my next block for the 1 piece rear seal and screw in plugs for that price I would do it.

 

[kevken1959]

If I could find someone local to machine my next block for the 1 piece rear seal and screw in plugs for that price I would do it.

Amen!