Calvan 11/16″ drill bit used with air ratchet and 1/2″ socket.

DenLors tools has sold hundreds of the Calvan spark plug repair kits and has had no reported failures. We’ve answered many questions about Ford spark plug thread repairs over the last couple of years and have included them in various places on our site. Now in this auto repair blog ALL of the frequently asked questions to date are posted here in one central location, if you don’t see your question answered, feel free to use the comment form and ask. Included here are questions about repairing spark plug holes after Lisle, Napa, Auto Zone, or other brands may be thicker than the Heli-Coil, but still have managed to fail and allow the spark plug to blow out AGAIN. We are not out to discredit any other spark plug insert company, we just know from our customer feedback what works and what just works for awhile. The questions below answer questions from real customers with this serious problem. We recommend the Calvan Ford spark plug insert repair kit as the best solution for Ford 1998-2004 4.6, 5.4. 6.8 SOHC (2 valve) engines, the following will help show why.

Question:  Are there different size or oversize inserts available for the Calvan insert tool and are they included?

Answer:  There is only one size thread insert for the Calvan repair kit and 8 are included. There is only one size because once the Cal Van is installed, it will not blow out and there is no need for an oversize insert. The Calvan insert is larger than competitive brands and Cal Van’s larger stronger design is one of the reasons it can last the life of the cylinder head. To date the Calvan insert is the largest insert available, that’s the reason it can be used when other brands fail. 

Question: I have a 1999 Ford F150 with a 4.6 liter Triton engine with 126,000 miles on it. The number 3 spark plug blew out of the cylinder head. I called my local repair shop and was told that this was a common problem with this design engine because of the extremely thin (aluminum) casting in the spark plug area of the engine head, there is only about five threads for a spark plug. How is the Calvan insert better?

Answer:  While it is true there are only five threads for the spark plug in this design engine for the spark plug and the Calvan repair insert has five spark plug threads as well, the Calvan spark plug insert is steel not aluminum and the insert itself is held in place with ten external threads. The Calvan spark plug insert improves the design and durability at fraction of the cost of replacing the cylinder heads; and if replacing the heads they would have the same design weakness.

Question: I am selling my truck as fast as I can get a spark plug to stay in long enough to get rid of it. I wanted to use a Heli-Coil because I won’t have to drill, but the thread tool isn’t long enough to reach in the spark plug recess, any suggestions?

Answer:  I personally recommend the Calvan spark plug repair kit because it is a better repair, but if you would rather use the thinner Heli-coil insert, the HEL5396-14 has the longer thread tool than the standard Heli-coil kit.

Question: I have Ford van that has had a parts store insert installed previously, it has blown out and I want to know if the Calvan insert will work since the old insert has left a bigger hole now?

Answer: Yes, the Calvan spark plug repair insert is larger and has worked well for our customers before, saving the expense of replacing the heads. Read on for more information.

Question: I bought a rebuilt head and come to find out one of the spark plug holes had a repair insert, it blew out last week. The cylinder head has a warranty, but I cannot afford the down time of pulling thread all over again. Will the Calvan insert repair this hole?

Answer:  Yes, the Calvan insert is a thicker beefier repair that you don’t have to worry about. And I always tell our customers that when purchasing a rebuilt head of this type to be aware of the possibility that inferior repair inserts may be in the head. Buying a brand new head would insure that there are no cheap inserts, but you would be stuck with the original weak design. The Calvan thread insert repair saves down time, money and is stronger due to the material being steel alloy instead of aluminum like the original threads.

Question: I need to know the size or dimension of the outside of the insert, to know if it will be large enough to repair the spark plug hole threads that have already been fixed once before?

Answer: The outside diameter of the insert is .73″ or 18.65mm, this is measuring on the most outer part of the threads. If a HeliCoil or regular size Timesert (not a Big Sert) was used before in the original repair this will work well. 

Question: I have an insert that blew out after an engine rebuild, I can’t afford the down time to have the engine pulled AGAIN. The insert that’s still on the spark plug is not a thin Heli-Coil, it appears to be a bigger insert, maybe an oversized thread repair. My question is; Will the Calvan thread insrt work in an engine after the bigger insert has blown out? The outside diameter of the bigger insert is .63″ or 16mm.

Answer: Yes, I can say this because the drill bit included in the Calvan 38900 spark plug repair kit is 11/16″ (.6875″ or 17.4mm) so what you’re telling me is you have a smaller hole than what the drill bit size is in our kit. So as long as the previous repair was drilled in the center, the Calvan will work great. Also the Calvan has a guide that fits in the spark plug recess so drilling and tapping will be centered every time, if you have a good view of where you’re working or not.

Question: Does the CalVan insert accept the same spark plug or will I have to remember to use a different spark plug in the repaired port?

Answer: The CalVan insert uses the same spark plug and has the identical taper and same number of threads, just stronger steel not aluminum.

Question: The price for one insert seems high, are you sure I don’t get more than one insert for this price?

Answer: I understand this seems like a lot but for an insert of this quality it’s like many things in life, you get what you pay for. Who wants to trust a weaker design insert to hold in a spark plug, if it fails on a coil over plug design it may break a $50 plus coil, require the job to be done over again, or worse cause extensive engine damage requiring the replacement of the head.

Question: How long will the Calvan spark plug repair last?

Answer: The Calvan inserts are designed to last the lifetime of the engine and are stronger than the original threads.

Calvan’s leak down tool to determine when the valves are closed.

Question: Time Sert says the only 100% way to know the valves are not open is to remove the valve cover and inspect the cam, making sure that it is not depressing the valves on the damaged spark plug hole. Do I have to remove the valve cover with the Calvan Ford spark plug insert tool kit?

Answer: No. The Calvan tool kit allows the mechanic to verify valves are closed with an included cylinder leak detector. Plug the rubber stopper from the leak detector into the spark plug hole with a low amount of air from an air compressor going through the hose. The rubber cone will pop out of the spark plug hole when the valves are closed. The video shows this as well.

Question: How do I know all the aluminum metal shavings are out of the cylinder?

Answer: borescope is used to make sure all foreign debris is removed. A video inspection scope can be used as well, we have a fairly inexpensive video based scope, that in our opinion is better and easier to view than the fiber optic borescope shown in use in the instructional video.

Calvan’s metal sleeve or guide is used to center the drill bit and the tap.

Question: I’m afraid I might start drilling or tapping the hole crooked, am I going to damage my head beyond repair?

Answer: With the Calvan specialty tool kit that we sell, since it is made specifically for Ford 4.6, 5.4 and 6.8 Triton engines, it has a guide that fits into the spark plug recess to perfectly guide the drill and the tap making the repair centered, even in hard to access areas.

Question: Will my spark plug be properly grounded through the engine, since the insert will have JB weld on the threads?

Answer: I’ve only had one person ask this. The answer is yes. JB weld or Loctite with some other brand inserts is being used on the threads, but there is a large enough percentage of metal to metal contact that provides ground, to allow proper firing of the spark plug.

Question:  The Ford cylinder repair kit instructional video (showing the repair done with the engine on a stand) is good, but can this repair be done in the vehicle?

Answer:  Yes, the video is showing how the kit is used with an engine on a stand, however the tool kit is designed to be used on an engine that is in the vehicle.

Question:  There doesn’t seem to be much room under the cowl area of my truck. How can I drill in that tight area?

Answer:  This repair kit is used in tight areas, on trucks and even in vans. The drill bit, which is used in the guide so the hole is drilled in the correct position. And to allow drilling to be done in confined areas, the drilling is actually done with an air ratchet. The drill bit accepts a 1/2″  socket that is used with your air ratchet, so drilling is done on a right angle. The guide is also used with the thread tap, so making a perfectly centered hole is easy.

Question:  On the CAL38900 – Hi, I’ve got a 1998 Ford E350 w. Triton v10 (6.8L) with a blown plug ( second from the front on drivers side.) I’m just wondering what length the tap tool is? I only have about 6-8″ above the engine to work with and was hoping I could do this without dropping the engine. Also, is there any special type of air-ratchet I should use on the job?

Answer: I understand your concern. This kit is designed to be used in the vehicle, even in vans. The length of the tap is 7 3/8″ long. The bit is 7″ long. A 3/8″ air ratchet like the Ingersoll Rand 109xpa works well.

Question: I am working on a motor that has had a cheap parts store brand insert installed. The problem is there’s a holes burned along the side of the hole. I’m not sure if the Calvan insert is big enough to take care of that extra width. Is there a larger insert available?

Answer: Yes. But first since you already have the Calvan kit I would try it first. The top of the Calvan insert has a shoulder that may help seal up the extra hole that was burned through from driving the vehicle with the compression leak along the side of the part’s store insert. If there is still a compression leak heard, after trying the Calvan insert I would turn the motor off quickly to prevent burning an even larger hole beside the insert. We have the Time Sert 5600 which uses an insert inside another insert to end up with the largest outside diameter possible. See the following listing for more information on the largest Ford Spark Plug Thread Repair kit available. It requires the entire kit because it is larger, but it’s still better than pulling the head and replacing it.

Related Links and Products

Ford Spark Plug Blow Out Problems How to Repair – Original article

Calvan 38900 Insert Kit – Product in this blog for sale. 

Calvan 389-100 DLT Inserts – Additional inserts sold separately.

Expedition Cylinder Head Removal w/Body Off – NOT required with the 38900 DLT see what you’re missing 

Time-Sert and Big Sert Thread Repair Kits FAQ’s

Difference in Lengths for 5553 and 38900 Reamers