Prototype Open Chamber L88/ZL1 Head
 

This head recently came to me out of a shop in the midwest in a package deal. I thought it was pretty cool and thought I would share some pics with anyone else who has a sickness for this stuff like I do.

This head has the end plugs and angled exhaust port flanges like cast iron and 392 and 842 aluminum heads. It has open combustion chambers and round exhaust ports as found on the 3946074 head. It has a raised casting number pad with no numbers on it and 2 other casting pads with no numbers. The numbers may have been removed by GM or the shop that has the head, I don't know. It looks like the head was used for flow testing. The intake ports have the walls beneath the valves filled as shown. I removed the filler for one to be sure there was no damage underneath.

Anyway, I just wanted to share with anyone into this stuff.


Happy holidays,


Jason

Looks like a very early 074 based on 2/16/68 cast date. They must have used the plug castings and changed the combustion chambers? How do the combustion chambers look? Cast or have they seen the die grinder?

Thanks for the questions. It is not a 074 head. It is a prototype open chamber head from before the 074 was made. It is based on a 842 head with the plugs on the ends and the sloped exhaust ports. The 074 head used an exhaust port with a different external design that was more upward and rounded. Yes, the chambers are originally open chamber with some casting still intact.

Hard to believe a machine shop would remove the numbers.. why bother? Surprised it does not have an O- number. So apparently this may have been the test bed for the soon to come 074 heads ? Neat stuff ! Thanks for posting !