How should I plug these coolant ports?

khwilm · November 23, 2018, 9:13pm

Any ideas on how best to plug these two coolant ports? This is an 86 XJ Series lll engine and I plan on using the early triple SU carbs with the triple intake manifold. I had thought of using freeze plugs but the finish of the surface is a rough cast and I doubt I could get a good seal. The diameter of the port is approximately 1 1/16" -26.91mm. Any suggestions would be appreciated.
Thanks - Kevin

L.Lynn · November 23, 2018, 9:47pm

Hi Kevin,
I used ‘freeze out’ plugs on mine but I cleaned up the surface (with a file and then sandpaper on a dowel) and then used JB Weld to ‘complete’ the sealing.YMMV
Cheers,
LLynn

kassaq · November 23, 2018, 11:08pm

My SII E-type engine is from an 87 XJ6. I am running a series I triple SU intake. The two holes in my engine’s head are threaded and plugged with a large (female) allen socket plug. I think if you can get the plugs and tap, you will be able to easily thread and seal the holes. If you use some axle grease on the tap, you will be able to keep the shavings from going down into the head.

Ray_Livingston · November 24, 2018, 12:07am

Just use regular cup-style core plugs. Clean the bores well, slather the plugs with JB-Weld, and push them in. Did this ~15 years ago on a friends S2, and haven’t had a single problem.

Regards,
Ray L.

khwilm · November 26, 2018, 12:58pm

Thanks. It looks like I’ll go the plugs with JB Weld if i can find two 1 1/16" plugs. Spent all day yesterday stopping at every local auto parts store trying to find two 1 1/16" plugs. Is anyone aware of any online sources?

Geoff · November 26, 2018, 1:41pm

Check ebay under freeze plug 1 1/16… there are a number of listings.

khwilm · November 26, 2018, 3:02pm

Thanks, i was looking for the cup style plug and only saw one listing.

Ray_Livingston · November 26, 2018, 3:10pm

Seems to be an unusual size for the US, but lots of them on EBay in the equivalent
Metric size of 27mm. Even though most come from outside the US, they can still get here in about a week.

Regards,
Ray L.

Tucurious · November 26, 2018, 6:33pm

I once made an aluminum blanking plate that looked like an intake gasket. With gasket, plate, gasket and some sealer it worked with a 4 lb. radiator cap. IIRC there was some weeping but if I used a thicker plate next time it might have resolved that. Every time I look at a straight port head I think if I take this to a shop for a valve job I’ll have them bore those holes round and maybe leave a shoulder. It shouldn’t be a problem if the head is already in a machine set up for a valve job.
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