Guest Grapeman Posted June 21, 2016 Share Posted June 21, 2016 I have read much about the intake manifold soft plugs on the 401. I recently had my engine apart for head work. Upon putting it back together, I realized that I did not re-install the large soft plug in the manifold. Now, the motor runs very rough at idle. I have checked the usual, dwell, timing, wires, points, etc. My specific question is: What is the purpose of the soft plugs? If they are leaking or not installed, will that effect engine performance....more specific...idle? I have plugged the exhaust channel that was used to pre heat the carb as it is not necessary in Calif. Also, I understand that a standard dorman 2" freeze" type plug will work. Anyone familiar with these and there functions...? Link to comment Share on other sites More sharing options...
1965rivgs Posted June 21, 2016 Share Posted June 21, 2016 Are you referring to the type of plug which looks like a freeze plug and is installed in the bottom of the intake manifold? This is simply a plug for the exhaust crossover passage and shouldnt affect idle quality. Did you install the intake manifold gaskets upside down? This can be seen just by looking at the manifold sealing surfaces. You will need to remove the manifold again to install the plug anyway....... Tom Mooney Link to comment Share on other sites More sharing options...
Guest Grapeman Posted June 22, 2016 Share Posted June 22, 2016 Tom Thank you for your input. Can you be a bit more specific on how to determine if intake manifold gaskets are installed correctly? How do I tell by looking at them? The service manual says to have the points on the gasket to face in (toward motor). Looking at my installed gaskets, I believe I have the points facing out. I have attached a pic of my installed gasket. This is on passenger side. Is the pointed part of the intake gasket the one that the service manual is describing? If so, then I believe I do have them on incorrectly? your thoughts? Link to comment Share on other sites More sharing options...
1965rivgs Posted June 22, 2016 Share Posted June 22, 2016 If you have them installed incorrectly you will be able to see the raised sealing bead exposed when it should be covered by/underneath the manifold. Tom Link to comment Share on other sites More sharing options...
Guest Grapeman Posted June 22, 2016 Share Posted June 22, 2016 Tom Based on your explanation, it appears that I have them installed incorrectly. Can I re-use the gaskets or do I need new ones? They are the fel-pro steel gaskets. Link to comment Share on other sites More sharing options...
telriv Posted June 22, 2016 Share Posted June 22, 2016 Since they were crushed improperly to begin with for less hassles I would install NEW gaskets. They don't cost that much & would save time removing & replacing the manifold AGAIN!!!. Link to comment Share on other sites More sharing options...
Guest Grapeman Posted June 23, 2016 Share Posted June 23, 2016 OK, I installed NEW intake manifold gasket and it solved the problem. I did have them installed incorrectly. Running smooth as can be....And the soft plug was intact. There was a "cover" that came off the soft plug, but it did not compromise the plug at all. I did butter it up with JB weld to make sure it would not leak. All is good. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now