800-734-8665 x251 We have customers calling everyday asking for thread repair kits to repair a spark plug hole that was previously fixed, but the repair failed. Although we sell kits for other makes, Ford seems to be the one with the most spark plugs blowing out. Many vehicle owners and auto repair shops end up going with an inexpensive thread repair from a local parts store to save time and because it's convenient. This is understandable because the vehicle is not usable until the repair has been made. However, time is not really being saved if the repair does not last. It even costs more in the long run when the repair isn't done with a quality kit. We have more information about repairing holes for Ford Blown spark plugs. We've been selling spark plug thread repair kits since 2005 to help our customers get their vehicles back on the road with a lasting repair. We find the best fix for our customers. We sell a lot of the Time Sert 5553's which have an insert that measures .68" on the outside edge of the threads. It is muc thicker than a thin coil of wire like a Helicoil and thicker than the solid Heli Coil Sav-A-thread. This is a Big Sert so it is big. Therefore it's big enough to repair the holes when wire type and other thin type inserts were used and have failed. The Big Sert is held in with a locking pin embedded in the side of the insert. It also used lock tite. And thirdly uses the self locking design by the installation driver finishing the bottom threads and cold rolling them which expands the bottom of the insert locking it into place. This is called cold rolling. We like this kit a lot and it works great. It's a good fix. Another kit we sell for limited applications from around 1998 to around 2004 is the Calvan 38900 DLT. It is only for 2 valve Fords with 4.6, 5.4 and 6.8 engines. It does not work on DOHC engines because of the way the line up piece goes into the spark plug well. It does have an insert which is bigger. It measures .73" on the outside diameter which is a little bit bigger than the ones that come in the 5553 Time Sert Kit. It is a different brand so it is held in differently. The manufacturer recommends JB weld and the top of the Calvan insert also has a shoulder on it that tightens down similarly as the head of a bolt does, it tightens up against the contact surface. Now for the biggest. The Time Sert 5600 is the largest Ford Thread repair kit in the world. It has tooling in it that allows you to install an insert inside an insert. This makes the outside diameter the largest available measuring at .77" on the outside of the threads. So if there has been an insert fail that was big or if there was a compression leak on the outside of an insert this is the kit. We have have had customers call that have had a hole burned on the outside of the old parts store repair insert. A hole actually burned through an extra portion of the cylinder head because of the leak. If that is what you have we recommend the Time Sert 5600 because it is the largest and the best chance of repairing the sparkplug hole without replacing the head. If you have a question regarding spark plug thread repair or other applications visit our site or call us at 800-734-8665. http://wiseautotools.com/brands/Time%...