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Unusual 12G940

Posted: Sat Sep 19, 2020 8:53 am
by imack
I've got 12g940 head with some odd features, not sure if its modified or factory. It has drillings for 11 studs but they've been blanked off with brass plugs but these plugs are not stud hole diameter, they're the same diameter as the brass plugs as the gasket face of the head. The head appears to be standard thickness and the plugs skimmed with the head face.
Secondly the intake ports are 'flat topped' rather than round. I initially thought someone had modified it but the 'flat top' looks cast rather than having being ground.
Anyone seen these 'features' before?

Re: Unusual 12G940

Posted: Sat Sep 19, 2020 1:00 pm
by iain1967s
The intake ports look like they are a bit offset from the stud centerline - possible the core wasn’t positioned properly when it was cast, but more likely the head wasn’t clamped correctly when the round ports were originally milled?

Re: Unusual 12G940

Posted: Sat Sep 19, 2020 4:33 pm
by cooper64
Have seen these heads fitted to the last of the allegro with the brass plugs in the 2 spare end head stud holes

Re: Unusual 12G940

Posted: Sun Oct 18, 2020 7:24 pm
by imack
Quick update on this for anyone interested. Today I drilled the brass plugs. They are just 8mm deep plugs pressed into a counter bore in the extra two stud positions, not a one piece solid slug of brass in an oversized stud hole that I feared they might be. They are infact the same solid brass plugs that are fitted to the gasket face of the head. I've never come across a 33mm intake valve head before that's been factory drilled for 11 studs.