Bisquik1959 Posted March 8, 2021 Share Posted March 8, 2021 I need to replace my engine in my 83 F100 with the 5.0. I was planning on getting a remanufactured long block to save time instead of doing it myself with machine shop time etc. If I look at Napa or Autozone for example, it mentions that my truck has smog on the back of the heads. I looked and didnt see anything on the back of the heads. Was there a CA emissions and a 49 state emissions in 1983? This truck was bought new in Arkansas and I want to make sure I get the right engine and can pass smog next year. Link to comment Share on other sites More sharing options...
Rembrant Posted March 9, 2021 Share Posted March 9, 2021 Hey Bisquick, They are referring to the Thermactor ports on the back of the cylinder heads. See below picture of my 1984 5.0 as it was originally. There is a tube that runs across the back of the engine and attaches to each cylinder head just above the frost plugs. As far as I know, all small block Ford heads from about 1978-1996 should have these ports (somebody can correct me if I'm wrong). I have a set of late 90's GT40 heads on my 5.0 now, and they do NOT have these ports, but most heads will AFAIK. Link to comment Share on other sites More sharing options...
Bisquik1959 Posted March 9, 2021 Author Share Posted March 9, 2021 Hey Bisquick, They are referring to the Thermactor ports on the back of the cylinder heads. See below picture of my 1984 5.0 as it was originally. There is a tube that runs across the back of the engine and attaches to each cylinder head just above the frost plugs. As far as I know, all small block Ford heads from about 1978-1996 should have these ports (somebody can correct me if I'm wrong). I have a set of late 90's GT40 heads on my 5.0 now, and they do NOT have these ports, but most heads will AFAIK. Mine doesn't have anything there. I just have a tube going to the passenger side manifold from the smog pump. Will I be able to block off those ports or are they all listing the wrong engine? Link to comment Share on other sites More sharing options...
Rembrant Posted March 9, 2021 Share Posted March 9, 2021 Mine doesn't have anything there. I just have a tube going to the passenger side manifold from the smog pump. Will I be able to block off those ports or are they all listing the wrong engine? You can buy plugs for them just Google thermactor port plugs I know places like Jegs and Summit sell them. I believe they are 5/8” so some people just use bolts to plug them. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 9, 2021 Share Posted March 9, 2021 Mine doesn't have anything there. I just have a tube going to the passenger side manifold from the smog pump. Will I be able to block off those ports or are they all listing the wrong engine? You can buy plugs for them just Google thermactor port plugs I know places like Jegs and Summit sell them. I believe they are 5/8” so some people just use bolts to plug them. 5/8-11 x 1/2" or so for Windsors. Use a crush washer under the head of the bolt. Every V-8 truck engine of this era should have come with a thermactor crossover, check valve then plumbed to the A.I.R. pump with a bypass valve. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 9, 2021 Share Posted March 9, 2021 5/8-11 x 1/2" or so for Windsors. Use a crush washer under the head of the bolt. Every V-8 truck engine of this era should have come with a thermactor crossover, check valve then plumbed to the A.I.R. pump with a bypass valve. Here's what they are talking about. This is from our page at Documentation/Emissions/Thermactor Systems. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 9, 2021 Share Posted March 9, 2021 Here's what they are talking about. This is from our page at Documentation/Emissions/Thermactor Systems. Yep! So you see 9B449 (the thermactor tube) 9A487 (the check valve) and 9B289 (the bypass valve) coming from the pump. I didn't realize something as early as an '83 would have another tube for preheating the catalytic converter. I know my non-catalyst heavy duty vehicle used air injection to burn off some of the HC and CO without resorting to a cat. But that doesn't hold true for vehicles under #8,500. Link to comment Share on other sites More sharing options...
Rembrant Posted March 9, 2021 Share Posted March 9, 2021 Mine doesn't have anything there. I just have a tube going to the passenger side manifold from the smog pump. Will I be able to block off those ports or are they all listing the wrong engine? You can buy plugs for them just Google thermactor port plugs I know places like Jegs and Summit sell them. I believe they are 5/8” so some people just use bolts to plug them. Here's a plug kit fyi: https://www.jegs.com/shop/m20ProductDisplayView?catalogId=10001&langId=-1&productId=1681664&storeId=10001&pgGrp=catNav As mentioned though you can just use bolts, many have. Link to comment Share on other sites More sharing options...
Bisquik1959 Posted March 9, 2021 Author Share Posted March 9, 2021 Here's a plug kit fyi: https://www.jegs.com/shop/m20ProductDisplayView?catalogId=10001&langId=-1&productId=1681664&storeId=10001&pgGrp=catNav As mentioned though you can just use bolts, many have. Hmmm.... those diagrams dont match what I have. Nothing on the back of the heads and just a hose from the smog pump to the passenger side exhaust manifold. Looks like I will get the new engine and block these off. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 9, 2021 Share Posted March 9, 2021 Hmmm.... those diagrams dont match what I have. Nothing on the back of the heads and just a hose from the smog pump to the passenger side exhaust manifold. Looks like I will get the new engine and block these off. What's the chance you have a carb swapped EFI engine in your truck? Because that's what it seems like from here. Link to comment Share on other sites More sharing options...
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