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tips, technology, tools and techniques related to vehicle driveline components

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BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Spark plug holes
Posted by: BlownMGB-V8
Date: January 21, 2009 04:23PM

Here's a new one for you, it turns out there's a whole industry built around repairing spark plug holes in aluminum heads. Apparently Ford gave this industry a tremendous boost by spending the last 10 years making and selling defectively designed heads, and have had a rash of spark plug thread failures ever since. But for us this is good news, as some very high quality spark plug thread products are now on the market, at reasonable prices, for on-the-car repairs. Names like Lisle, Helicoil, TimeSerts and Lock-n-Stitch sell them, and the process is essentially to ream out the hole, tap it to a larger size, vacuum out the chips, screw in the solid one piece insert using a high temperature locktite, and swage it in pace to lock it securely. The inserts are either steel or hard anodized aluminum, leaving a better than new thread.

Why did Ford do this? Evidently they felt 4 threads were adequate to hold a spark plug in a cast aluminum head, and then just for giggles they used weak robots that couldn't hold torque. A local shop tells me they will do this repair on the car for $200. That's a bargain, as long as only one blows out. The kits to do these repairs run about $350 and if you find yourself in that position you have to ask yourself, if one blew out how likely is it that another will also. But for our aluminum heads it's usually just the #1 cylinder. That means we have some very useful new tools at our disposal, and a convenient service just down the road.

Jim



Edited 1 time(s). Last edit at 01/21/2009 05:49PM by BlownMGB-V8.


Bill Young
Bill Young
Kansas City, MO
(1337 posts)

Registered:
10/23/2007 09:23AM

Main British Car:
'73 MG Midget V6 , '59 MGA I6 2.8 GM, 4.0 Jeep

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Re: Spark plug holes
Posted by: Bill Young
Date: January 21, 2009 04:54PM

Jim, good information, but this wouldn't have any connection to your engine problems coming home from the winter meeting would it?
I haven't used any of the new kits, but have been using Helicoil and ReCoil products at work for years now in all sorts of aluminum parts with great success. I've also used them on a couple of engines, one to do a spark plug thread in a motor cycle and again on an exhaust manifold stud on my Midget. The only problem I ran into was how to remove the tang on most thread inserts without losing it. Not a problem in a part where the hole isn't blind or where you can't pick it up and shake it out, but on a cylinder head on the engine that might be a bit more problem since most of the inserts are stainless steel and non magnetic. Perhaps this would be a good place to use a pair of hemostats to clamp the tang tightly so it wouldn't go flying off when you break it off.


hoffbug
Tony Hoffer
Minnesota
(323 posts)

Registered:
10/15/2007 05:25PM

Main British Car:
Olds 215 EFI

Re: Spark plug holes
Posted by: hoffbug
Date: January 21, 2009 06:57PM

Most of the machinists I know use the timesert inserts...


ex-tyke
Graham Creswick
Chatham, Ontario, Canada
(1165 posts)

Registered:
10/25/2007 11:17AM

Main British Car:
1976 MGB Ford 302

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Re: Spark plug holes
Posted by: ex-tyke
Date: January 21, 2009 07:16PM

Hmmm.....Thought I'd read recently that Ford did not recommend spark plug hole repair using a Helicoil type product - their solution was to invest in a new head. ;-(
As far as this hole failure issue and low plug thread engagement, I think this pertains to the newer Triton Engines and not the aftermarket Ford Racing heads for our SBF 302 engines. The plug reach (thread engagement) on a 302 aluminum head engine is about 5/8" - or about 12 threads :-)
....so if you're running a sbf 289/302, not to worry.......


ex-tyke
Graham Creswick
Chatham, Ontario, Canada
(1165 posts)

Registered:
10/25/2007 11:17AM

Main British Car:
1976 MGB Ford 302

authors avatar
Re: Spark plug holes
Posted by: ex-tyke
Date: January 21, 2009 07:37PM

JIm, you've opened up a can of worms with this thread. For the heck of it, I just did a search on this Ford issue and it gets better.
Quote:

Broken Spark Plugs.

Ford has redesigned the cylinder head on the 5.4 engines used in Ford trucks, Expeditions, Mustangs etc. unfortunately the new design has a different problem. When removing the spark plugs in these newer 5.4 Ford engines the spark plug can break leaving a metal sleeve (electrode shield) in the spark plug hole. The threaded part comes out but the remaining portion stays behind and can be a real nightmare to extract.

Ford has made a removal tool kit, the Rotunda 303-1203 for removing the spark plug sleeve when this break occurs. The Rotunda 303-1203 is a specialty tool that has been in huge demand from many unsuspecting repair shops that were performing regular maintenance on their customer's vehicles. The Ford TSB describes how to try to prevent the break, although the procedure yields less than desirable results...........

This could get expensive for Ford if it gets to the recall stage........


MGBV8
Carl Floyd
Kingsport, TN
(4511 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

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Re: Spark plug holes
Posted by: MGBV8
Date: January 23, 2009 03:26PM

Heh, heh, all my favorite F.O.R.D. acronyms are leaping to mind. ;)

Sorry to hear you had problems with your truck, though.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Spark plug holes
Posted by: BlownMGB-V8
Date: January 23, 2009 05:26PM

It's fixed. New insert, new plugs, new coil. About $500 total. But, that beats the heck out of a head swap. I let the shop do it because they had the tools (about $350) they had the experience, and it's very hard to get in there and work on it. Seemed worth it. The other plugs looked just fine and torqued down with no problems whatsoever, so hopefully I'm done with that problem. This was plug #6 fwiw.

I like the looks of those inserts. It's good to know that's an option.

Jim



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