[Lloyd-TX]

I'm finally trying to tie up all the "loose ends" on my 455HO engine before Jeff paints it for me. I'm down to one problem - there's a factory 1/2" pipe plug in the passenger side cylinder head that's most likely been in there for 31+ years. On the original 400 in my Formula there's a temperature unit (haven't checked yet to see what exactly it's for but my new repop 455HO harness has a connector for it) in that hole so I'd like to install it in the 455HO head for originality purposes. I've alreadt broken a stout 3/8" breaker bar, tried an impact driver and a good 3/8" air impact wrench with no success. Before I break out the drill bits, any advice?

BTW, the color of the quart of paint I bought from Scott Tiemann looks perfect (as far as I can tell).

TIA,
Lloyd

'72 Formula 400 - soon to be a 455HO, TH400, A/C, etc.; Lucerne Blue with Medium Blue Interior
Restoring a '72 GTO 455HO, TH400, A/C, etc.; Sundance Orange with Parchment bucket

[Lloyd-TX]

I'm finally trying to tie up all the "loose ends" on my 455HO engine before Jeff paints it for me. I'm down to one problem - there's a factory 1/2" pipe plug in the passenger side cylinder head that's most likely been in there for 31+ years. On the original 400 in my Formula there's a temperature unit (haven't checked yet to see what exactly it's for but my new repop 455HO harness has a connector for it) in that hole so I'd like to install it in the 455HO head for originality purposes. I've alreadt broken a stout 3/8" breaker bar, tried an impact driver and a good 3/8" air impact wrench with no success. Before I break out the drill bits, any advice?

BTW, the color of the quart of paint I bought from Scott Tiemann looks perfect (as far as I can tell).

TIA,
Lloyd

'72 Formula 400 - soon to be a 455HO, TH400, A/C, etc.; Lucerne Blue with Medium Blue Interior
Restoring a '72 GTO 455HO, TH400, A/C, etc.; Sundance Orange with Parchment bucket

[george kujanski]

Try a 1/2" dirve impaact wrench; give it a blast clockwise (in the tightening direction first to try to break it loose) then loosen. I have tried this alternating method of tighten,loosen, etc. with somme success. Your results may vary.....

Regards, George

[Malky]

I get a grade 8 bolt (six dashes on head), carefully grind the threaded end square to fit tightly into plug (assuming you have square hole in plug), hammer square end in and reef on bolt head with 1/2" breaker bar with pipe extension. I have never found heat any good. I am not sure tightening the sucker to free it up is a good idea, either.

[ron thorne]

spray with Deep Creep(by Sea Foam), rap it hard with a upside down ball pein hammer( or something similar), spray again, let set overnight(if possible), use tool steel ground to fit nice and tight, bang it again with hammer and Deep Creep.

[Blackcat]

A little heat with a torch often solves the stuck plug! Done it plenty of times if the Impact will not move it.

Usually I'm found working on my Pontiac. If you want to find me Look for the white picket fence and all the old Pontiacs parked outside. And the half dissembled engine sprawled all over the driveway!

[NOZZLENUT05]

I agree with the heat....works all the time in the Chebbie garage. We use PB BLASTER too. Seems to work pretty good. I would try the PB BLASTER first to see if it will work. Sometimes tightening it first also works too. But I would do the heat trick first. Sometimes using a smaller tip such as a brazing tip will help concentrate the heat on the plug.

[NOZZLENUT05]

how can you do two things first? DUH.what i meant to say was, try the pb blaster first...just a penetrating type oil. If that doesn't work, then try the heat. Sorry for the confusion.

[Lloyd-TX]

Tried the 1/2" air impact, broke the first 1/2" to 3/8" adapter and promptly rounded out the square hole in the plug on the second try. Drilled it out using progressively larger bits (ended up with a 5/8"!!!) until just a "wisp" of the threads were left. Then used a large tapered reamer to give the 1/2" pipe tap something to dig in to and rethreaded the hole. I tried a brass pipe plug in the hole looks like it will seal just fine.

Thank goodness that's over with!

Thanks for all your replies,
Lloyd

'72 Formula 400 - soon to be a 455HO, TH400, A/C, etc.; Lucerne Blue with Medium Blue Interior
Restoring a '72 GTO 455HO, TH400, A/C, etc.; Sundance Orange with Parchment buckets

[Skip Fix]

I've got the same deal to address with my ^xs. Teh machine shop put the heater nipple in the head without the plug! Eventhough it probably would have leaked once in the car if I didn;t pull it.