size of bolt needed to plug head

[sheff2720]

does anyone know the size of the bolt i'll need to plug the smog ports on the back of the heads?

 

[Modular2v]

i would like to know the same thing

 

[5.02GO]

3/4-10 or 5/8-11 cant remember which though.

 

[mackey]

3/4-10 or 5/8-11 cant remember which though.

5/8-11

 

[88_GT_5_oh]

glad i found this. i gotta remove that last peice of smog crap to run my downpipe for my turbo

 

[TheUser]

someone said that a 5.0 spark plug will screw in there, so I guess you could take one of those to the hardware store and match 'em up, but I'd prob. trust mackey w/ his 5/8-11 suggestion

 

[Morales]

Im assuming this will also be the same bolt needed for a pair of Trickflow TW heads as well? I also need to plug the back of my heads as i removed all that smog nonsense..

thanks

 

[TheUser]

Im assuming this will also be the same bolt needed for a pair of Trickflow TW heads as well? I also need to plug the back of my heads as i removed all that smog nonsense..

thanks

the ports should be same on the Trickflow heads if the heads are expected to bolt up to the stock emissions equipment, which I assume they are.

 

[88_GT_5_oh]

yes they are the same on the tw heads... thats what i am running. i looked at it and its the samea s stock.

it would make sence that a spark plug would fit cause those are 5/8 arn't they?

 

[bobcatv8]

This one might need to be a sticky! It's been asked many times.
It is 5/8-11 thread size.
The hole goes straight through the head front to back. Each exhaust port ties into the passage for the thermactor emissions.
Sometimes the hole on the front of the head is used to mount accessories, if so you will have to use a bushing {that will also serve to plug the hole} that shrinks the thread to 7/16 thread. The Ford part # for this special bushing is
F4ZZ-6E086-A. I have heard it is available from other sources too. If you ever have to swap sides with your heads you will have to be bushed on both front and back of the head IF it is used for an accessory mount. It has been my experience that the rear hole is very carboned up and may have to be cleaned or tapped out on used heads. There isn't much room to manuever against the firewall on a Mustang so check that out too.

 

[5.02GO]

Spark plug is 1/2-20 i believe

 

[TheBocSez]

I was lazy and bought the plugs made by Trick Flow from summit for a couple of bucks each.

 

[88_GT_5_oh]

I was lazy and bought the plugs made by Trick Flow from summit for a couple of bucks each.

link or part number? i am placing an order with them anyway.

 

[TheBocSez]

part number is TFS-51400265.

Thermactor plug 5/8 - 11

 

[795.0pacecar]

I just broke the ceramic ends off of a couple old spark plugs and they threaded right in.