1275 Water bypass nipple

[erstearns]

Bypass nipple on the underside of the head is broken off flush. Tried WD40, heat and "easy" out with 4 foot cheater to no avail. Anyone know what the thread is on the nipple? Seems to be sort of 5/8 but with a thread between fine and regular. If I can find the right thread chaser I can drill and clean out the threads. Otherwise, any good ideas on how to seal it? Weld patch, bash in a copper or brass plug?...... :madder:

 

[spritenut]

Many are corroded off or beyond use.
I do not remember the size of the threads but it is a basic plumbing fitting that I bought at the hardware store. (not home defect but a real hardware store)
Maybe a 3/8 pipe nipple.

 

[mightymidget]

I found that if you cut the wall of sleeve with a small metal saw, it releases pressure so part can be removed without thread damage. if you cut to far it just puts a line in the threads. I have not tried it in the area you are talking about tho

 

[Spridget64SC]

Thread is 3/8" BSP, British Straight Pipe. Not tapered and doesn't match with SAE stuff. Matches with some JIC/plumbing and AN type threads. MM's suggestion is a good one. Use a Dremel tool and cutoff wheel and then a punch and hammer to curl the piece into the bore. Probably can drill with a 1/2" on the drill press to thin a bit more. I usually drill with a 9/16" on the mill and then thread for a 3/8" NPT plug since I'm usually doing this for racing purposes. If I've centered really well on the hole, the 9/16" drill will cut everything out and leave the threads in good condition. Just a cleanup with a dental style pick.

HTH,
Mike Miller

 

[Hap Waldrop]

These are really hard to remove when not broken off, and I never gotten one off without using heat. When they are in whole, I use a pice of dowel to put into the ID, then I grabbed REALLY tight with a pair of vice grip, and use a fair amount o heat, and pentrating lube, and be patient.

Since your is broken off flush, I's do what Mike says and keep drilling it out with larger drill bits. We don't even run thm on the race cars, we either use a water pump that the bypass is undrilled or we tap the bypass in the water pump to 3/8" and put a bolt in it, then use a plug on the cylinder head, the Copper S 1275 head did not run the byass from the factory, those head just have a big brass plug in the head.

 

[tomshobby]

Hold on, use a smaller amount of heat and apply paraffin wax. Must be paraffin and not the newer fake wax. This works great for drain plugs and other things stuck in a cast iron part.

 

[erstearns]

Will try the wax and heat..... tried heat and WD40 to no avial. If that does not work will drill out with 1/2 and 9/16 and tap with 3/8 iron pipe thread tap. If all else fails can drill threads out and pound in a copper plug. Any suggestions as to which type to try? Have seen cup type that looks similar to standard copper type cap but tapered for hight pressure fluid sealing.

 

[Hap Waldrop]

Eric, just be patient, that fitting is without a doubt the most difficult thing to remove for a A series engine.

 

[dklawson]

the Copper S 1275 head did not run the bypass from the factory, those head just have a big brass plug in the head.

I have one of the first 500 1275 -S engines. It came with the AEG163 head and it has the bypass nipple. When I rebuilt the engine I installed a later big-valve head based on the 12G940 casting. It also had the bypass nipple. I thought it was not until they went to the A+ block that some of the heads were built without the bypass nipple.

Regardless, I have an acquaintance who uses almost the same method as you to remove the nipples from the head.

 

[nomad]

If you know how to grind an engraving graver I have a couple of homemade tools for this kind of job. Made out of old triangluar files. I would cut thru to the threads 2 cuts approximatly 60 degrees apart. Then use a good punch to drive the small segment out. Use the punch to loosen the remainder and it should screw out easily. Just my technique!

Kurt.

 

[erstearns]

Being somewhat impatient.........I drilled out the aluminum with a 12" 1/2" bit. The chuck of the drill was up against the crank, as it drilled in it offset some and I was left with some aluminum on one side and engine block on the other. It was smooth and since there was no way the alum thread was coming out without some real effort I went ahead and tapped with a 3/8" pipe thread. Gobbed on some thread sealant and screwed it in. Fingers crossed.....hope for no leaks.

 

[dklawson]

It looks good to me. Let us know how it works out.