When I had my LPG V70 I found that the best plugs by far were the bog standard copper-cored Denso ones, as listed for the B5252S engine by Denso. From memory they came in at about £1.50 - £2.00 each I think!
I tried all sorts over the years it was necessary to change them every 10k, otherwise misfires would start to appear.
Fancy multi-pin plugs of whatever make would last no more than a few thousand miles, with Bosch being utterly useless.
I reckon to have used probably 25 sets of plugs in the 9 years / 250,000 miles I had the car, and never had any issues with the Denso plugs.
The other thing I did was to replace the plug leads every 70-80,000 miles.
For LPG to burn properly everything electrical has to be in really good condition, so I got into the habit of cleaning up the distributor contacts every oil change, and making sure that the lead guides were intact and not allowing leads to chafe against the cylinder head.
Jack
|