Spark plug boss / bulge in combustion chamber - remove to ??

DaviesDJ · Post by **DaviesDJ** » Sat Mar 16, 2013 5:24 pm

Beginning to port and sort on my home made flow bench etc, got thinking about the spark pug boss. Very large on the 300 heads, noticeably on the to et, wonder what the benefit of it being there is?? I am tempted to remove them to aid in swirl and spead of combustion?? Do you guys remoe and blend with the rest of th chamber, am going for a heavy skim to bring CR up as I have a two part intake manifold that can be adjusted to the height loss, what do you guys reckon????

DaviesDJ · Post by **DaviesDJ** » Sat Mar 16, 2013 5:26 pm

Terrible syntax due to auto txt-

thinking that the river head swirl could also do with having these removed?? And Ben skim 3mm off for CR on the 300s

Greg55_99 · Post by **Greg55_99** » Wed Mar 20, 2013 5:13 pm

I read in an OLD magazine article (from 1963) that those doohickey’s in the chamber are to prevent spark plug wetting on startup. They come in two different shapes depending on whether they are early or late 1963-64 castings. Visit Dan Jones’ site. Looks like he just got rid of them.

http://www.bacomatic.org/gallery2/v/hid ... 0/album12/

Greg

sidecar · Post by **sidecar** » Wed Mar 20, 2013 6:38 pm

Mr MuscleManta and I worked on a 3.9 lump a while ago, for one reason or another we had to gain some volume in the combustion chambers. Those funny lumps were the first thing to be removed. The engine starts and runs fine!

DaviesDJ · Post by **DaviesDJ** » Sat Mar 23, 2013 5:36 pm

I'm sure it would still run fine, but as far as optimising burn and swirl??? They look awfull on the rover and worse on the buick 300!!

Boosted LS1 · Post by **Boosted LS1** » Sat Mar 23, 2013 6:39 pm

If you wet the plugs it'll never start. I'd certainly leave the boss in place if planning to use a carb. With efi set up properly I'd be happy to remove the boss.