Lotus Elan

Core Plugs

PostPost by: Britcar82 » Thu Jan 31, 2019 9:47 pm

I just finished rebuilding my engine and an engine stand to test it on. I was only able to run it for about 30 seconds before I realized the carbs that I thought would work needed to be rebuilt. I have sent those off to Joe Curto. Unfortunately, Joe has a 8 to 10 week backlog. In it's short run time the only issue besides the carbs seemed to be that all 3 core plugs are weeping. The 2 smaller plugs are 1 5/8" and the large plug is 2". These sizes correspond to several responses on this forum. I ordered new plugs from Ray at RD Enterprises and the set I received were marked 1 41/64 and 2 1/16. I'm trusting that the slightly larger size will help with sealing? Also, per the machine shop that did the work and supplied the plugs I put The Right Stuff on the edge of each plug. It did not seem to do it's job of sealing the plugs so does anyone have any suggestions for something else? In searching the internet I have found a few ideas:
1. Permatex Ultra Black
2. The Right Stuff (which did not seem to work for me)
3. Permatex Indian Head Gasket Shellac
4. JB Weld. This is recommended by John Twist who is the MG equivalent to Miles Wilkins. I'm not sure about using JB Weld as the MG engine uses a domed style core plug as opposed to the cupped style on the Lotus engine.

Any suggestions/hints on installing the plugs so they won't leak would be appreciated.

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PostPost by: miked » Thu Jan 31, 2019 10:29 pm

I have always used Wellseal. Never had a leak. Remember they are meant to blow out if a block froze. Mike :)

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PostPost by: 2cams70 » Fri Feb 01, 2019 1:58 am

Did you clean out the holes properly with some wet and dry before installing the plugs? The best stuff to use is an anaerobic adhesive like the OEMS do - I used some Loctite 243 in my engine

http://www.dpaonthenet.net/article/5372 ... ounts.aspx

Be aware also that you aren't supposed to knock them in with something flat by the edge. I used a circular piece of nylon cut to fit the ID of the core plug from an old cutting board. I then knocked them in with a socket. The purpose of the nylon was to protect marring the core plug surface with the socket.
Last edited by 2cams70 on Fri Feb 01, 2019 2:34 am, edited 1 time in total.
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PostPost by: billwill » Fri Feb 01, 2019 2:07 am

Did you hit them with a hammer?

When they arrive they should have a slight bow to them that faces outward, You put them in with sealant then hit the centre with a soft eg Brass drift to flatten the disk. this makes the edges expand outwards to grip the recess.

Hmm, this applies to the shallow ones, I'm not sure about the cup shaped ones. The one on the underside of the head at the rear is a shallow one, methinkx.
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PostPost by: RichardHawkins » Fri Feb 01, 2019 8:30 pm


I took advice from Loctite UK who advised Loctite 243 as used by Ford UK. This is the same advice as 2 Cams. I bought from core plugs international who I think advised on fitting method.

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