8 plug 4 plug z20

[dukerollo]

My friend picked up a 1980 510 parts car. We are taking the engine out to put in his 79. I am fairly ignorant of the z series engines, when looking it over I saw 4 plug wires and assumed it to be a 4 plug head. It is not. We pulled the engine today and looking at me on the intake side of the head were 4 more plugs. Someone had either swapped heads or distributors at one point in the car's life. 

 

My question to you gurus is, how is running half the plugs in the short term going to affect things? 8 plug distributors don't exactly grow on trees. Should I time it like an l20b? Should there be 2 coils? The car only has one and doesn't show any evidence of ever having a second. 

 

Thanks for for any insight you can provide. 

[datzenmike]

Head was swapped. All Federal cars to June '80 had the 4 plug head and distributor. All California emissions and Federal cars from July '80 on were 8 plug and distributor.

 

The 8 plug heads ran a different timing and polluted slightly less that it. A single plug will run something like 8 degrees, dual plugs about half that.

[dukerollo]

Cool. Thanks. I’ll just time it a bit more aggressively.