The Stovebolt Site Forums The Shop Area Engine Shop 235 block drain

Finally got the drain plug out. It's steel fine thread but it's just a bolt. What is the correct part I need to have.? Some say a petcock but they also say they are fragile. Is there a better set up? I'm not going for originality I want something that's functions well when changing anti-freeze.
Thanks in advance...Steve

Really the original system works pretty well. 1/4" NPT Petcock. Just don't gorilla the thing in and it will work great.

http://www.summitracing.com/parts/rnb-61106

Nice part about this one is you can put a hose on it.

fine thread bolts aren't 1/4" NPT, 9/16", and 5/8" have the same thread pitch, but I don't really know about diameter, the taps are quite different in size. Are you sure it is a bolt? What to the threads look like in the block?

i have to clean it up crud on the threads. I used a 9/16" socket it was a hex head so I assumed it was a bolt. I have it soaking right now and its too dark outside to check the block threads. Been fighting it all day so it's beer-O'clock now. I'll post what I find out.
Thanks Steve

Its probably a 1/4 ib. pipe thread. That's what comes in it & has a 9/16 hex head.

Pipe plug 1/4"... But it's steel not brass? I'll replace it with a brass plug or stainless steel. Is it a good idea to use anti-seize or just gasket sealer? I assume I'll be opening this plug again in the future.

I like brass. Use pipe sealant tape or goo.

I like Permatex #2 or Indian Head sealant for this application. They go on wet, which lubricates the pipe threads for a tight fit on tapered threads, and stays somewhat flexible for easy removal for draining the block.
Carl

Got to thinking...did they put a block drains in all 235? Ours is a 56 block and my uncle thinks that they had these block drains when anti-freeze was not used. After anti-freeze became popular Chevy did away with the block drains. My uncle maintains it was a step backwards. They do seem like a good idea.

That is an interesting question.

"bock drains" - could have been two petcocks, or one petcock and one threaded plug.

The 1955 and later Owner's Manuals refer to the drain cock on the right front of the radiator and the drain plug on the left rear of the 6-cylinder block.

"Both" (two) drain cocks are referred-to in the 1954 and 1955-2nd Truck Shop Manuals (and, for earlier 216s/235s?).

All 235's had block drains.
All small blocks for that matter I have seen had them also.
I will need to check the 230, 250, 292's, but I am sure they had them also.

So I was trying to edit and delete a post or two in the other block drain thread and instead deleted the entire thread.

Oops.

Sorry about that.

It's been awhile since I had to delete anything in here... mashed the wrong button.

Feel free to re-add your information in here...

Carry on.

-W

OK......got the block drain plug out but nothing drained out? I tried a coat hanger nothing...I'm going to make up a tool maybe like a machnist reamer or a milling cutter. If I get that far what will I need next ? I got a bit of black stuff on the end of the coat hanger but the hole is completely filled.
Thanks Steve

Have you flushed the cooling system yet? Perhaps try pushing some air or water back into the drain hole once you can adapt a 1/4" pipe nipple. When I had my motor apart i had it hanging from one end off my engine hoist. I ran water and air into the block back and forth until all the crud stopped coming out and just ran clear. I would guess a couple of pounds of sand and scale came out.

Mark

Man....I got it open...used a bell hangers twist drill. Turned it by hand and drilled out black fine sand. Then I used the wire coat hanger end that's twisted like a cork screw pushed that in and out a bunch of times. My wife's idea was a small baby bottle brush worked also. I pressurized the system with water ...nothing....back to the drill bit and wire coat hanger. The wire went in 6 inches and that did it. Pressurized the system again and at first lots of air then goo then clear water . Next step will be to use Bars Leak Flush with the block plug reinstalled then drain the block. I hope I got it all out if there is something I missed or can do better please let me known....thanks