Weiand manifold fitting question

[DWinTX]

I have a Weiand 7503 aluminum manifold that I'm using on my 65 poly build. I bought it used a couple of years ago and just went to test fit it in the engine. There is a plug in the intake floor below the thermostat housing that someone plugged with what looks like a plumbing pipe plug with a square head. The problem is the head hits a casting boss in the lifter valley. I'm sure this was meant to be plugged with a hex head style plug, or at least inserted from the top.

The problem is that it won't come out. I put the intake in a vise and used a long breaker bar but it won't budge. I PB Blasted it and let it set for an hour, still won't move. Tried whacking the wrench with a mini sledge, no go. I think it may have been stripped. So the question is, would there be any problem cutting the head off flush with the bottom of the intake? I don't know why it's even there, so I can't think of why I'd ever have to remove it since it would open a coolant passage into the lifter valley?

But, these intakes aren't made any more and there are no others made for a poly. Used, these are now going for $500-$700. So I don't want to screw anything up. Does anyone know why that hole is there and if it would ever need to be opened?

 

[miller]

From the looks of it, a few options...

1) Like you said, cut off the head. But, if you ever need to get it out...

2) Use a propane torch, just to 'flash' heat the aluminum, around the plug. Then try to take it out. Aluminum expands with heat quicker than steel. Just don't let the plug itself get too hot.

3) Since you have access to the hollow backside of the plug, could drill a hole through the plug's head. That can help relieve the tightness of the plug, and make it easier to get out.

 

[DWinTX]

From the looks of it, a few options...

1) Like you said, cut off the head. But, if you ever need to get it out...

2) Use a propane torch, just to 'flash' heat the aluminum, around the plug. Then try to take it out. Aluminum expands with heat quicker than steel. Just don't let the plug itself get too hot.

3) Since you have access to the hollow backside of the plug, could drill a hole through the plug's head. That can help relieve the tightness of the plug, and make it easier to get out.

I'm worried #'s 2 and 3 could bite me in the butt if it's stripped. Then I have to drill and tap for a bigger plug, and I really don't want that hassle. I've had several issues and delays already.

I just can't imagine why it's there anyway. The only thing I could think of was a temp sensor, but there's no where to run the wire.

 

[5.7 hemi]

Do this, drill it out so there is nothing left of the plug. get some 1/8 thick aluminum and tig weld it to cover the hole. Problem solved! If you don't have anyone local, send it to me and I'll do it for ya. You'll just have the shipping both ways.

 

[69Bee]

Use an 8 point socket of the appropriate size, use heat/penetrant and hit it with an impact. First a few hits tightening, then reverse it. The forward motion will break it loose and make it easier to remove. Even if it strips, use the next size pipe tap, and install the flush hex head pipe plug with Teflon paste, and you will be good to go.

 

[mopar 3 B]

I can not tell if the plug is solid or hollow. Cutting or grinding the head down may create a big water leak. Looks like a good spot for a brass hex plug and teflon.

 

[KarNut46]

Agree w/69Bee. If heat won't break it loose try heating it fairly hot then let it cool. Some times the added heat will cause a thermal shock that can break the bond that the rust has created. Another thought: what if the last guy used loc-tite? Considering the dire outcome should the plug work loose that is what I would do. Heat will break the loc-tite bond. That will be an interesting poly build. Good luck.

 

[lewtot184]

looks like a hollow plug. cut off the square and tap for 1/4" hex pipe plug.

 

[DWinTX]

Thanks for the suggestions guys, and the welding offer 5.7 Hemi. I'll try some heat tomorrow and see how it goes.

 

[CudaChick1968]

Once you get the plug hot, press an old candle to the bottom (or any exposed threads), and heat it up again. The wax will melt into where you can't get to and will let you remove it. You may need to use the candle two or three times but it WILL work. I have to pull old plugs out of used manifolds all the time and have yet to damage anything with this technique.

 

[miller]

The heat bit will work, if done right...and your holding your mouth right.

For years I had to deal with aluminum and magnesium airplane engine cases, getting plugs, and busted studs out, using heat to break things loose.

Of course, if you get the aluminum too hot, and you melt it...:eusa_boohoo:

 

[super-bee_ski]

Do this, drill it out so there is nothing left of the plug. get some 1/8 thick aluminum and tig weld it to cover the hole. Problem solved! If you don't have anyone local, send it to me and I'll do it for ya. You'll just have the shipping both ways.

Do what Zack suggested.
Eliminate it.

 

[DWinTX]

Well, I tried to use the heat today. Did no good. I heated it to about 400 degrees, per the infrared thermo. Tried to cycle it hot to cold 4 times. It's about 35 degrees here today, so I heated it and then set it outside for a while. Tried it with the impact, just rounded the corners. Even tried the wax trick that CudaChick recommended. I don't think rust is an issue, it's an aluminum manifold and with a brass plug (I think).

I don't think there's any doubt this was cross-threaded, so I cut it off and tapped it as you can see in the pic. I'm not much of a fabricator so I was pretty proud of myself until I tried to put the hex plug in. It wouldn't go. I knew the size and pitch were correct but after thinking it through, I realized the plug is an NPT thread and my tap is standard. Crap. Tried to find a 5/8 thread bolt at the local auto parts and hardware stores. No one has one that big in a fine thread. So I guess I'd have to order it online.

I know the best course is to find someone to drill it and weld it up, but I took this week off to try to finish this engine. I don't know how long it will take me to find a shop to TIG it. But it'll probably cost me another day at least. So I had another thought. I ran all of the air lines in my shop myself, including sweating the pipe. Could I solder or braze this up? If I filled the hole with solder flowing into the threads, it seems like that might work. What do you think?

 

[mopar 3 B]

Fill it with aluminum rod that way you can set a brass block on the bottom of the hole while filling and will not have to deal with cutting or grinding a stopper when done.

 

[5.7 hemi]

Drill it out completely, no brass and tig it up. Its a 15 minute job to weld up the hole.

 

[miller]

Or bring it to me, and I'll get it out for you. Retired, so usually around all day.

PM me for address, if interested. I'm at Tom Bean, Tx., just south of Sherman.

 

[DWinTX]

Thanks for the offer and the advice folks. I got lucky and found a machine shop about 10 miles from me that can weld it up today. It's over there now.

 

[miller]

Uh-oh. Can't remember the shop's name, but they did welding on my trans case. Took 2 weeks, and only got it done while I was standing there. Could of done better job in my sleep!

Maybe you'll have better luck!

 

[DWinTX]

The name of the shop was Hooks, but no worries. Just got back with it and it looks great. The machinist told me that the reason I couldn't get the plug out was that it had been epoxied in. :confused5:

 

[5.7 hemi]

Cool! Now on to bigger and more expensive things, lol!!