240/E-31 & 2.4L block

[Tony Genovese]

I have a "little" problem. Engine's out of the car...due to an ahem, "miscalculation" on my part, actually make that major brain fart, I over-adjusted the cam timing on my motor & caused piston crown/valve contact on start-up. I put a substitute L28 in my motor's place in meantime, but now I'm faced with varying possibilities on how to go about fixing my cylinder head. It's an E-31 head, a good one, so I don't want to toss it. Only the exhaust valves were contacted. The bottom end looks fine...pistons aren't damaged, just slightly nicked/scuffed where the valve edges hit. Everything I know tells me to replace all the exhaust valves (I do have a spare set of valves). I'm assuming even the slightest contact will ruin the valves. Anyone ever have an experince like this? It's not a catastrophic failure, just a hiccup. But I wanted to pose this to the forum to get some advice so I can cover all my bases...Thanks for any & all help. TG

[SteveK]

For what its worth change them.

They may look straight but stick them in a drill and spin them up and check for wobble with a dial gauge

If you try and straighten them, you'll spend hours and still wont get them right, (got one of those tee shirts somewhere) then they wont seat properly and consequently wont seal properly, then you run the risk of melting one (or the seat) under load due to gas bypass, bits fall in cylinder and rather than spend what $100 on new ones you'll be building a new bottom end.

[e_racer1999]

i would say change them. send me a PM and we can meet up. i have some E88 valves that i'm not using

[Tony Genovese]

Thanks for the advice & offer to help!! Looks like I'm replacing exhaust valves & heading to my machinist.

[Curtis240Z]

Put in bigger valves since you are doing the head and drop it on the 280 block, free extra 400cc and a lot more torque.

[Walter Moore]

Your E31 head may have already been reworked once, but if it hasn't be aware:

My E31 still had the original brass intake valve seats in it. (I don't know why Nissan used brass...) Those seats have to be cut out when they go bad, and after they are cut out you basically have to up-size the intake valves to the 44mm valve and hardened seat from the L28 (280Z) This makes working on the E31 a little more expensive than it would be otherwise.

As for putting it on the L28, how easy is it to get racing gas in your neighborhood?:cheeky:

[Curtis240Z]

If you have the L28 with the dished pistons you can put on the E31 and run pump gas and still be ahead of the L24!