im interesed in the gm performance L88 replacment heads the only thing thats throwing me off is the catalog says semi-opened chamber is this a mistake or did they change the head the part # im looking at is 12363410 thanks mike

I don't know if this will mean much or not so PLEASE take it as trying to help..

To me a -206 head is a closed chambered oval port head. (96 to 97cc's).

A -215 head is a semi-closed chambered oval port head b/c it's laid back some by the plug side. (101 cc's).

A -781 head is an open chambered oval port head. (From 113 to 119 cc's??).

And finally a -950 head is an open chambered oval port "smog" head that has the area by the exhaust valve "squared" out so that there is less deck in that area. (From 112 to 124 cc's??).

Are they talking about closed chambered rect. port heads like a -215's chamber??

pdq67

With a semi-open chamber you are probally looking at around 110CC. It would be like the old L78, L88, LS6, L72?? heads. A great head on a bigger cubic inch engine but they are a little too large for a street 396 or 427. There intake ports are very big but can help kill some low end torque.