Only a few hours since installation, but the plugs appear to be working fine on my IO-520 and are a fraction of the cost of alternatives. Gap is a little tighter than I am used to, but so far, this does not seem to be an issue.

David F Verified Purchase

BG341 Spark Plug 18MM Long

Great value for the price. I bought 24 and all passed resistance testing check, none marginal.

David R Verified Purchase

BG341 Spark Plug 18MM Long

I have been using these plugs for over 200 hours now in a 260 horsepower TCM IO-470-N. Very smooth mag checks, they just work well. They are equivalent to the Champion RHB32E and Tempest URHB32E. I have an STC for these plugs for TCM IO-470 engines that use the equivalent plugs as well as IO-520 engines that use the equivalent plugs. The STC came out before TCM introduced the IO-550 engines so they are not included in the STC.

I have been using these plugs for over 2 years. Work great, but did have 1 that was DOA. I guess that would be expected considering they were made in 1960. At this price, I replace the plugs every annual instead of cleaning.

Very Good Item, good value and fast delivery.

5 stars for easy ordering, and delivery as promised. We had some of these that had been here for maybe 25 years. Decided to use them. Normal life and performance, which is my main reason for ordering them. Glad they were in your catalog. Our IA recognizes them as a no problem plug.

Very good plug

Be sure to look into the top of the plug. Some of them had some corrosion on the internal contact that I need to clean out. Once cleared they all passed resistance testing and work fine. I have used them for several years now. I am cheap so I will keep using them.. -)

Michael A Verified Purchase

BG341 Spark Plug 18MM Long

Great price on plugs, but be aware-these were apparently low-bid government plugs. I bought 24 for my twin. Out of the first 12 I checked, the average resistance is 3,200 ohms (vice about 1,100 for a new Tempest massive), still within limits, but not impressive. In about a third of the plugs, the insulator ceramic on the inside of the barrel covered part or most of the contact-leading to a weak spark on the bomb tester. I rejected about 1/3 of the first 12, then gave up and ordered some new production plugs. You can get by with these, but theyre not that good a deal after you sort through and reject the ones that dont work. I may just sell mine on eBay, but Ill be honest about their performance.