[gquincoces]

Hello, a newbie to this forum but I have 3 GTOs (66/389, 70/400, and 70/455).

I own a 70 GTO 455 Convertible auto 4BBl with the PHS documentation that is one of 241. I have rebuilt the whole engine and the cylinder heads have freeze plugs that I like to replace (I did the engine freeze plugs). I researched this forum and there are two sizes quoted in the same thread, one for a 1 3/16" size and one for 1 13/64", same post. There is no resolution discussed as to why the two numbers.

Are the differences so small it does not matter? I do not want any hassle, or having to disassemble the heads again if I use one that leaks at a later time. Hence this post.

Any help would be appreciated. AS stated above, when I ran my first search in Google ("GTO 455 Cylinder head freeze plugs") I wind up in this forum (here): https://forums.maxperformanceinc.com...d.php?t=850624

The first size quoted in that thread is made by Dorman for which a box of 10 has to be purchased, the 1 3/16" is sold individually in Ebay. I am not looking for cheap parts, I need the correct sized one (even if I have to buy a box of 10). Thanks. Guillermo

[25stevem]

The Dorrman part number for what you need is 555-020.
It's a 1 1/8" .470"deep.

[25stevem]

Sorry my above post is 100% wrong !

[gquincoces]

Originally Posted by 25stevem

The Dorrman part number for what you need is 555-020.
It's a 1 1/8" .470"deep.

that was quick and certainly worth the wait, Still a different size, but the writer took the trouble. So, thank you so very much. Guillermo

[johnta1]

Here is what I show for the freeze plugs:

Pioneer EPC-80(B) The EPC-80 is 1 3/8". (goes on front and back of head)

and EPC-134(B). it is 1 13/64". This goes where the intake bolts on (intake face side.)

(the 'B' is for brass plug)

[gquincoces]

Thanks for the information, I purchased the wrong ones, but I will try to cancel th order and get the right ones. Guillermo

[25stevem]

Here’s the info right off a set of my heads just to help you rest assured that indeed what John kindly posted for you is correct, unlike what I had in my first post trying to go by memory.

Each end of the head takes a Doorman 555-025 ( 1 3/8”. ) so you need 4 of those, and then on the intake flange they are 1 13/64”.
Mine are perfect circle brand PC 134.

[gquincoces]

Originally Posted by 25stevem

Here’s the info right off a set of my heads.
Each end of the head takes a Doorman 555-025 ( 1 3/8”. ) so you need 4 of those, and then on the intake flange they are 1 13/64” which is also 1 3/16”
Mine are perfect circle brand PC 134.

Ok 4 for the 1 3/8 and how many for the 1 13/64??

[Joe's Garage]

This is for the opening at the back of the head behind the intake.

The other side will have the heater hose nipple in it.

[25stevem]

You need 3 of the second type if your still running the nipple to hook up the heater.

[b-man]

Originally Posted by 25stevem

You need 3 of the second type if your still running the nipple to hook up the heater.

Incorrect.

Only one if you’re using the heater hose nipple on the passenger side head.

Two if you’re not running the heater and plugging the hole where the heater hose nipple would normally reside.

The intake manifold front coolant crossover covers two of the holes so certainly no plugs needed there.

[25stevem]

Thanks for the correction!
I’ve needed a spare at times though.