Inliners International Forums General Discussion Engines 261 spark plugs

What is the proper spark plug and gap for a 1962 261? The engine is now in a '49 1/2 ton chevy.

.035 if using points

.045 if using HEI

Thanks for the gapping info., but what model/brand plug is best to use?

Points: Autolite 85/86
NGK BR6S/B6S
If you can find early AC's AC44 S or R

Thanks, I'll go round them up.

Or Champion RJ12YC....

Everybody has an opinion as to what to use for spark plugs, but I have yet to see anything technical as to why I should be using one brand instead of another.
I would think the heat range you use is probably more important than brand, but I would also assume there are some differences between brands (when comparing apples to apples) but I have not seen the kind of data anywhere. If somebody has some real data, I would like to see it...

I have never seen any hard published tech data on plug comparisons but I can tell you from real world experience in almost 45 years of working with stock and modified engines that a manufacturers cross reference does not always work out. Case in point is although an AC xx crosses to a Champion xy or an Autolite xz on paper, if you read carefully you will note that often ONE number of the Autolite or Champ or whatever is covering 2 or more heat ranges of an AC or NGK as an example or vice versa. It makes you wonder just exactly which of the several it covers is the exact match. I've had engines not run well with the correctly cross matched Autolite and gone back to the AC plug and they straighten right out. Like I said this is not hard laboratory proof but it has been very very consistent in my experiences over the years.

The absolute worst plugs I ever tried were Splitfires when they first came out. Curiosity more than anything was the motive to try them.
Despite all the claims the car was now harder to start and got worse gas mileage. After 2 weeks I pulled them and returned them ( 30 day money back warranty ). Replaced them with a new set of AC R45TS - V6 Chevy 229 engine - and it went right back to normal.

Mike

Dear H 49;

I usualy don't get into these debates, but Gearhead & Mike are "right on" here.

After over 50 years of working in the automotive repair industry; It makes no difference on which brand, as long It's of high quality.

My personal way is to use the (brand) that came with the vehicle ie; AC in GM, Autolite in Ford, Chysler & AMC. Champion in industial & stationary engines and NGK in the Japs.

As mentioned; the heat range is the important factor to consider which is learned when the old/used ones are removed at tune-up time.

The 6 cyl Chev uses an AC 45. If you start there the rest can be learned later after the vehicle has been driven a while.

Good luck, Johhn M.....