Project 2 - Forty Minus SJM 21109

[robhc1000]

Good afternoon,

I have a Forty Minus that uses a 8 COM spark plug, what would be modern replacement for it please? Also the engine is seized, is this repairable? - I dont want to go to mad with this engine as have a working 102 which I am going to tidy up and repaint over the winter.

Rob.

[charlesp]

NGK AB 6 NGK A6 Champion D16

Best is the first, available cheaply online.

Seized doesn't mean dead. First thing is to work out which end is stuck..

[spiderg]

Hi, you will find previous posts about seized engines on the forum, however can I just tell you, this makes it a better feeling when it's restored. Just the thought of it being a solid lump to start with, then with lots of patience it's brilliant to see and hear it running.
Whatever end is seized, my advice is to let it soak in a petrol/diesel mix for a good month. Don't attack it with a hammer. Winter is almost on us so you're in no rush, give it time and get it right. It will come loose, whether it's in one piece is entirely up to how much patience you have.

Search the forum, the topic has been talked about numerous times.

Good luck
Gerard

[The Tinker]

A mixture of 50/ 50 acetone and ATF (Automatic transmission oil) works very well to free up stuck parts.

[robhc1000]

Thank you gentlemen, I will gently take it to bits tomorrow night and see whats what.

Updates to follow.......

[robhc1000]

NGK AB 6 NGK A6 Champion D16

Best is the first, available cheaply online.

Seized doesn't mean dead. First thing is to work out which end is stuck..

The spark plug is the same as the one used in my 102, I have taken the old one out of the forty minus - The collar on the forty appears to be too long to fit a NGK AB6, does that have to be removed from block first?

[charlesp]

I suspect that the collar you refer to is in fact part of the plug itself. 8COM plugs were, together with many other earlier designs, made to dismantle for cleaning. Frequently it's just the inner bit that people remove.

[Collector Inspector]

NGK?

Not for my flock.

B

[david1230]

For my 71' Silver Century, I find the 8 COM plug to be better performing than the NGK or the Champion 16. Easy to dismantle and clean, the engine just purrs at most rpm's, as compared to the Champion which seems a little hot.
Although the Champion 16 seems to be the standard, I guess it depends on the engine (compression etc) and proper point and plug gap adjustment. Many swear by the NGK, but as for me I keep it and a Champion 16 for spares.
I also like the fact that the 8 COM dismantles for a thorough cleaning... those Brits went all the way to minimize spark plug problems on open water.
My aging uncle was a mechanic all his life and he said he had never seen a plug like the 8 COM...saying that it would have been so easy to get all the grit out of its innards and always being able to replace a perfectly cleaned plug all the time back in the motor.

[charlesp]

Sadly the 8COM is no longer manufactured. It was discontinued some years ago.

[skyetoyman]

8COM plugs do appear on ebay but tend to be fairly expensive

[robhc1000]

Right, will have a go at unscrewing collar then. Thank you.

[mrford]

Hi Look up Tams model A parts they have champion 3x three peace take apart plug brand new sit down hold your breath 27 dollars good you only need one don't know if the heat range is correct and they have motercraft 34 for 3 . 50 this will have the same heat range as the 3x ! VIC