MN47 inspection and L24 build help

[s30zgt]

Over the weekend this I pulled this MN47 off a 1984 Nissan Maxima. I have a 07/1971 240Z with a e88 head L24. Its in need of a rebuild and thinking that the e88 will need work anyway, I thought it might be a good idea to work with a head with a better starting point. I like the idea that i can use my SU's in the mean time and switch to O.E.R carbs or their Sports Injection ITB setup later down since it already has injector port notches.

 

This is the first time I've pulled a L series head so while it looks good to me (no corrosion,no cracks) and i will be taking it to a machinist eventually, I was wondering if there are any glaring issues with this head.

 

Here are a few pics of the head.

 

Ive read as many MN47 threads as there are on hybridz, but most were about using them on a L28 block with flat top pistons and the resulting detonation, retard timing, and general issues with that combo but nothing about using them on a L24 block. Most of the info i could glean on using it on a L24 block is to eyebrowing the block or risk the valves self clearing themselves.

 

This is kinda what im shooting for in terms of power on a safe and reliable engine. Im not too concerned about the power number but using it more as a personal benchmark.

 

From the OZDAT engine utility, my compression ratio should be around 9.79 with a 39cc combustion chamber which is what ive read to be the size on the MN47. From the info Brapp posted, its better to run a lower compression ratio with full advance timing than it is to run a higher comp and have to run the timing retarded. From anyone experience, is 9.79 comp ratio as safe number to run the correct timing or will I experience pinging and have to retard on a MN47/L24 block combo?

 

Thank you all for your help and insight.

[Heroez]

Ive got a mn47 too in my head collection, and did some reading back when. I think you are correct that the mn47 would be better because of the design. Be sure to use pistons that match the heads chamber shape to take advantage!

[s30zgt]

Yeah i wanted to use the MN47 since it was a high quench design for detonation resistance, had injector notches, and steel valve seats already installed so it would have most of the work done that i would need on my e88.

My plan was to utilize the stock flat tops that come with the l24 block. Are you suggesting that i get custom pistons that have matched dish to decrease compression or a slight matched dome to increase compression?

[Xnke]

The stock pistons will work fine. the head came off an l24, it will go back on an l24 just fine.

[s30zgt]

Ok great. One last question. I still have a lot more to research on this part but which camshaft would be better to use? The e88 cam, the mn47 cam or invest in a aftermarket cam? I know the e88 cam is externally oiled so if i used that one i would have to install a spray bar into the mn47. The mn47 cam was probably focused on lower rev range power and fuel economy so it probably not the right cam to use compaired to the e88 cam right? Thank you again for all the advice.

[s30zgt]

On the brochure i posted above, the L24 they have listed runs a compression ratio of 10.5:1. Ive searched for more info on this engine and from what i read, they didnt release this engine due to tightening emissions regulation. Does anyone have any detailed info on this engine and how they were able to run 10.5:1 safely back in 70's? Was it ever released or even exist?