What plugs work best in a 8ba with 4 stroke .060 overbore ,mild cam offenhauser heads,running iffy intake and 97s stromberg carbs (2x2). Looking for suggestions of different plugs.Thank you!
Used to run Champion H 10 or Autolite AL7. there's an NGK crossrefrence but I can't remember what it is.
These plugs are NOT correct for Offenhauser heads. They are cast of aluminum and have deeper plug holes, requiring longer reach plugs. The plugs mentioned are fine for stock iron heads, but will be badly shrouded when used in the Offenhauser heads. Also, do not chamfer the bottom of the plug holes as some suggest because it will remove threads needed to hold the plugs in the weaker aluminum. Offenhauser heads are problematic, because the plug holes are too deep for "L" series Champions (and equivalents), but not deep enough for "N" series Champions (and equivalents). There is a thread on the "Ford Barn" where this subject has been dealt with in detail; I will try to find it and post it here.
I tried Champion and Autolite 216. Didn't work with my 286 CI build. Switched to NGK's, problem solved. Went with the hotter plug of the two choices. B-4L. I run Offey heads also. Had a lot of fouling with the Champion and Autolites.
I don't doubt it with those short plugs. You say you had to go hotter with the NGK's; I don't doubt that either.
Here are the thread I am referring to : https://www.fordbarn.com/forum/showthread.php?t=302200&highlight=Offenhauser. The bottom line is Champion "N" (or equivalent) series (3/4" reach) with a .21 spacer. EDIT : I found the original original thread that has all of the details : https://www.fordbarn.com/forum/showthread.php?t=272052. Here's what the body of the plug should look like when screwed into the head. (This not a perfect example, since these are Edmunds heads. On Edmunds heads, the spark plug location has been moved enough so it is not directly over the exhaust valve; this allows the use of extended tip plugs.) These are L82YC. In Champion nomenclature, "L" means 1/2" reach (full 1/8" more than stock) and the "Y" means "extended tip", which you can run with Edmunds heads. The important thing is that the bottom of the plug body is flush with the combustion chamber in the head. BTW, here is a picture of a stock (3/8" reach) plug in an Offenhauser head. Sure, the engine will run, but that doesn't look optimum to me. How about the color of the deposits in the transfer area; sumpin' ain't right,
I'm rather long of tooth, so my memory is not the best, but seems I used to run Autolite 216's in my V8-60. I also had Offy heads and had "cleaned" them up several times, to make sure they stayed flat and to enhance compression. The 216's seemed too short, but they worked great. At one point, I took the heads to a "machine shop" (I think it was a home for idiots) to have them pressure tested. The owners father chewed my ass out, saying I was running the wrong plugs. So enlighten me says I. He says that he is an expert on flatties, and gave me an NGK number, and has a set waiting for me at the local parts joint. I reinstalled the heads, put in the "correct" plugs, and turned over the mill to pump some oil. Didn't sound right, like it was turning over with no compression. The "expert" gave me plugs that were too long, and yes, I should have checked. I had exploded the end of the plugs, including the porcelain. This had scored the tops of the pistons and bent every exhaust valve. Luckily, I had a spare mill so I yanked and cranked 'till 2 in the AM to fix the issue. Went back to the 216's. The bad part is that was scheduled to leave at 6 that same morning to head for the vintage races at Laguna Seca. Turns out it ran fine, with the wrong plugs, and the dickwads at the machine shop refused to answer my calls.......
With respect, V8-60's are a whole other ball game. We are concerned here only with 8BA Offenhauser heads. One of the reasons I was so involved with the "Ford Barn" discussions is because I happen to have a set of never been installed Offenhauser 8BA heads in pristine condition. Thus I knew exactly what was involved. After much measuring and test fitting various spark plugs, we came to the conclusion that the Offenhauser heads were designed to run 5/8" reach plugs. The Offenhauser heads had to have been designed at least 70 years ago. Perhaps 5/8" reach plugs may have been available then, but we could find none available from any manufacturer now. Thus, the only practical solution was to run commonly available 3/4" reach plugs with a .21" spacer. I got into this first in 1961 when I was racing a flathead-powered early Ford coupe in "D/Altered". I had a set of Edelbrock heads for that engine that had been run with H-10's. The engine didn't perform all that well, and the bottom 1/8" of threads were all carboned up. After carefully cleaning up the threads, I consulted a Champion Spark Plug Catalog. It showed that Allard sports cars used "L" series (1/2" reach) spark plugs. A little research showed that early Allard's with flathead Fords used Edelbrock heads. I purchased the plugs listed. They fit perfectly and the engine ran considerably better. Thus, I have been sensitive to using the proper reach plugs in aftermarket aluminum heads ever since. Edelbrock's used "L" series plugs, and as shown earlier, they are a perfect fit for Edmunds heads. I have no experience with other makes of heads, but I would expect that they use the longer plugs as well. It only makes sense; aluminum is not as strong as cast iron and requires more threads to hold the plug. Offenhauser, on the other hand, are oddballs. I had a set about 25 years ago on an 8BA in a '36 3-window, and had the same problem. I ended up using some marine surface gap plugs that had the proper reach. Generally, that shouldn't have worked very well, but that engine had an MSD-6 box and matching distributor and coil. I have the Edmunds heads pictured above on the '51 Mercury in my '51 coupe. I installed the heads and plugs in 2016. I put several thousand miles a year on that combination, and it still runs flawlessly with the original plugs. The reason that I still have the unused Offenhauser heads is that the Edmunds have shown themselves to be superior because of the spark plug location and I have been lucky enough to accumulate several pair over the years.
Hi Tubman. Question on this old post, do we add the .21 spacer on top of the existing crush washer? Thank you,
I just posted the link to "The Ford Barn" because I thought it might be helpful to some folks. It was not my original information, but was posted by one of the experienced engine builders over there. I believe it was "Bored and Stroked" or "FlatJack9", both of whom are excellent sources. I would check over there with the original source, as second-hand information has ways of getting mis-interpreted more often than not.
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