zpodski

So I thought I would share what I found for the internet's collective knowledge but I know it is a 1.6 so no one cares...

I was killing some time looking at a valve catalog and found that the '96-01 Hyundai Elantra 2.0L exhaust valves should nearly drop into a 1.6/B6 head. RockAuto has the Enginetech EM3467 valve for $6.28/ea or $50.24 for the set of 8.

The OAL is 0.0035"/.09mm shorter but you can easily sink the valve while re-cutting the seat to solve that. The only "issue" comes from the stem diameter, as it is 0.001"/.0279mm thinner; however, the matching Elantra exhaust valve guides (SBI 1408571 -$24 for 8) are spec'd to the same OD with a slightly tighter ID compared to the Miata guides. The guide's OAL is 0.07"/1.778mm longer and will need to be trimmed for the proper guide installed height.

So for $50-$75 you too can upgrade to +1.25mm exhaust valves for your screaming 1.6 turbo build and save almost $100 over the supertech SS +1mm's Or end up buying a set of NOS SBI Inconel std size valves for $80 on ebay like I did. I killed time hooray!

Bonus oversized intake valve info: The BMW '91-00 328 intake valves are a +2mm (possible candidate to backcut and profile down to +1.5mm/+1mm) with a good stem diameter. The obstacle on this valve is that the stem is 0.0514"/1.306mm too long and has 3 keeper grooves. Rockauto - SBI 10695 for $7.12/ea. I'm tempted to grab a few and see how the BMW keepers interface with the Miata retainers OR what it looks like welding up the keeper grooves and re-cutting the stem tip for a miata 1G keeper followed by heat-treating/case-hardening or fitting lash caps but since I would have to cut an oversized valve seat first, I need to find a "junk/free" 1.6 head since I'll be staying stock for now.

Ted75zcar

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LeoNA

The reason the aftermarket manufacturers offer 1mm over valves is to offset the reduced installed height from cutting the seats. Sinking a valve always reduces output.

zpodski

I agree on not sinking valves if you don't need to. Since the stem length is only 0.0035"/.09mm shorter the valve installed height may well be within the FSM range anyways at original seat depth. If not sink em a smidge (easy/cheap/worse) or cut the spring bases down(better/harder/more$).

LeoNA

Could just use a thicker shim.