Coolant in the oil

[chickenwafer]

I would say you can ignore the manufacture when actual people have done it before and it has worked on more than one occassion. Although the manufacture does put a lot of R&D into what they sell and the proper way to use it.

Dave

[240ZMan]

I had the block deck and head checked for flatness today and the shop said both were fine. They suggested pressure testing the head and I've dropped it off at a different shop for that, although it will be at least a week before I get it back.

FWIW, both shops thought it very unlikely that the block would have an internal crack so the focus is on the head for now.

[chickenwafer]

rather the head than block- less expensive in most cases. Hopefully you will have it sorted out soon.

Dave

[240ZMan]

Just got a call back from the shop and the head has a hole in it. He says it's under one of the valve springs and "it's a gusher".

To recap, it's an N42 that was recently cleaned up by the previous owner with good condition (but not new) valves, stock springs, new valve seats, and a slightly warmed over cam. Until this I was very happy with the head.

The rest of my engine is as follows:

- N42 block with dished pistons

- I'm going to be installing a set of flat top pistons as part of this project

- 6:1 header with 2 1/2" exhaust

- Stock SU Carbs

I'm looking for feedback on what to do next.

Option 1) Get the existing N42 head repaired. I have no idea if this is really a good idea. I'm out of town and haven't seen the head yet, but the shop says he can't tell if it's a crack or a void. Do any of you have any experience with fixing these heads?

Option 2) I have an E31 head with the smaller valves that was cleaned up with SS seats by the PO. I could install this as-is.

Option 3) On the E31 head I could swap my warm cam over to it. I expect I would need to get new lash pads and carry the rocker arms over as well. Any other issues that might come up?

Option 4) Have a machine shop install the larger valves from my N42 head into the E31 along with the necessary machining to enlarge the valve holes. Swap the warm cam over as well along with the rockers. Probably not cheap. Any one done this?

Option 5) I also have a stock N47 head with about 80k miles on it. I could swap my cam to it, and replace my header with a round port unit. Still not cheap though.

Option 6) Anyone have an N42 head in good condition they want to sell

Thanks for staying with me on this. Looking forward to hearing from others who have done things like this.

[240ZMan]

BTW, the cam is .441 lift and 260 degree duration.

[Bambikiller240]

JMO, but if you have an L28 block, I wouldn't put the E31 head on it UNLESS you also go to the larger valves. (especially if you're going to use that cam, but even with a stock cam, I'd go for the larger valves)

[LanceM]

I'd go with option 6. Unless the head is a rare one it is usually cheaper in the long run to replace it with a known good one that hope that a repair holds. If it was a steel head I would have more faith in the repair than I would with aluminum, JMO. Going with the E31 with bigger valves would cost more than a reworked N42 head, plus depending on which E31 could you take the extra compression? Life is full of options, just most of the time none of them seem like "great" options

[livenbad]

If you have a blown head gasket (or water leak inside the head surface) you will usually see some discoloration around the water jacket hole

[livenbad]

also make sure the water jacket hole in the head gasket matches the head and block. I bought one that did not match up once.

[240ZMan]

also make sure the water jacket hole in the head gasket matches the head and block. I bought one that did not match up once.

I had looked at this very closely. It didn't line up as perfectly as I would like, but it wasn't bad enough either that it looked like it would be a problem.

[First Gen Z]

I've seen aluminum heads repaired many, many times with 100% success. They are easier to repair than iron heads by far.