JPHIL Posted August 25, 2015 Share Posted August 25, 2015 Just had my 346 engine rebuilt, and noticed that the freeze plugs were installed with the convex side turned inward. I seem to recall that these were designed to be installed with the convex side outward , so that a hammer strike would expand them into the opening. Advice ? Link to comment Share on other sites More sharing options...
Guest Posted August 25, 2015 Share Posted August 25, 2015 (edited) Depending how tight they fit before being hammered sometimes (rarely) they would almost turn inside out. I would be suspect of what you see. Perhaps they just used a lot of schmucky on the core plug and stuck it in place. Most shops today are used to Aluminum blocks and perhaps didn't hammer your plugs in. I would certainly question them. You don't need a core plug to pop out on the highway. Edited August 25, 2015 by Guest (see edit history) Link to comment Share on other sites More sharing options...
JACK M Posted August 25, 2015 Share Posted August 25, 2015 You are on to something.You should ask the engine shop why they did this, and when they don't know have them pull these out and replace them correctly. Link to comment Share on other sites More sharing options...
JACK M Posted August 25, 2015 Share Posted August 25, 2015 By the way, freeze plugs don't exist. They are core plugs or casting plugs.Sometimes a guy gets lucky and a core plug will pop out when it freezes. Link to comment Share on other sites More sharing options...
keiser31 Posted August 25, 2015 Share Posted August 25, 2015 (edited) Sounds like they were installed correctly to me. I imagine they would push out easier if the convex side was facing out. Edited August 25, 2015 by keiser31 (see edit history) Link to comment Share on other sites More sharing options...
Guest Posted August 25, 2015 Share Posted August 25, 2015 Correctly installed they should be installed dry, convex side out with one dimple in the middle from a ball pean hammer. I have installed hundreds of them this way and never ever had one leak. The old mechanic that showed me how to do this (back in the 50's) said if you had to hit it twice you should take it out and replace it. He even was upset if the dimple wasn't centered.The convex side is out and hitting the center expands the welsch plug so that it seals tight. Link to comment Share on other sites More sharing options...
HarryLime Posted August 25, 2015 Share Posted August 25, 2015 Most I have seen have the size and manufacturers name or logo on the convex or to say 'outside'. Are yours marked as such as viewed ? Link to comment Share on other sites More sharing options...
Guest newbymachineworks Posted August 25, 2015 Share Posted August 25, 2015 By the way, freeze plugs don't exist. They are core plugs or casting plugs.Sometimes a guy gets lucky and a core plug will pop out when it freezes.Thank you for addressing one of my pet peeves. Link to comment Share on other sites More sharing options...
Scotts_DG8 Posted August 26, 2015 Share Posted August 26, 2015 Were they done different my make/model? Here are a '70 Dodge 318 before and after it went to the machine shop. If you look close you can see the original blue paint on the plug before it went to the machine shop. This is how I recall all Mopar engines. Just a hard example being given. Scott.. Link to comment Share on other sites More sharing options...
Guest Posted August 26, 2015 Share Posted August 26, 2015 Those plugs in #9 are cup plugs, the other kind are Welsh or as GM called them in the 40's and 50's expansion plugs. Expansion plugs are concave or convex depending which side you look at. When they are installed and hit in the middle they expand and make a leak proof seal.Cup plugs are made an interference fit, are coated with a sealant and then driven home making a leak proof seal. The main difference is the thickness of the casting. It needs to be thicker when designed for cup plugs. Link to comment Share on other sites More sharing options...
Scotts_DG8 Posted August 26, 2015 Share Posted August 26, 2015 Thanks for the education on the different type of plugs. Scott... Link to comment Share on other sites More sharing options...
keiser31 Posted August 26, 2015 Share Posted August 26, 2015 Those plugs in #9 are cup plugs, the other kind are Welsh or as GM called them in the 40's and 50's expansion plugs. Expansion plugs are concave or convex depending which side you look at. When they are installed and hit in the middle they expand and make a leak proof seal.Cup plugs are made an interference fit, are coated with a sealant and then driven home making a leak proof seal. The main difference is the thickness of the casting. It needs to be thicker when designed for cup plugs.That is the reason I gave the answer that I did. Thanks also from me on the education of the difference. Link to comment Share on other sites More sharing options...
JACK M Posted August 26, 2015 Share Posted August 26, 2015 Yup ! Link to comment Share on other sites More sharing options...
c49er Posted August 28, 2015 Share Posted August 28, 2015 (edited) Here is the way I install them.... and have for 40 years.A driver that is flat and about 3/4 of the diameter of the plug..convex side out.A bit of sealer in the counter bore. Two or three whacks and the plug is just about flat, looks smooth and factory like.No big dimple in the middle of the plug. Edited August 28, 2015 by c49er (see edit history) Link to comment Share on other sites More sharing options...
Guest Bob Call Posted August 28, 2015 Share Posted August 28, 2015 Ball peen hammer is the poor man's sub for the Miller seating tool shown in Bob's post above. Link to comment Share on other sites More sharing options...
Guest Posted August 30, 2015 Share Posted August 30, 2015 Here is the way I install them.... and have for 40 years.A driver that is flat and about 3/4 of the diameter of the plug..convex side out.A bit of sealer in the counter bore. Two or three whacks and the plug is just about flat, looks smooth and factory like.No big dimple in the middle of the plug. I have an installation tool like the one pictured that has several different size drivers, and always thought of the tool as being for use installing the cup type plugs only. I have installed the convex type using a ball peen hammer while the tool pictured was right there in the tool box. It just never occurred to me that it would work just as well on the convex type. Thanks for opening my eyes. Link to comment Share on other sites More sharing options...
JPHIL Posted September 11, 2015 Author Share Posted September 11, 2015 One more question.... If using a sealer, would a permanent type be better than a flexible one, ie Permatex #2. Link to comment Share on other sites More sharing options...
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