240Z E31 Head Gasket Options

[Zed Head]

Thanks very much for this thread link. I think it proves my theory that the gasket is for a F54 block based on the water passages drawing you so kindly mentioned.

 

I asked the engine builder if he felt he could punch in four more holes in the gasket and use it, but he was very apprehensive.

 

This gasket is not your typical composite head gasket it is very tough and most likely difficult to punch.

 

Still at a loss why the later blocks had reduced cooling passages.

It could probably be drilled.  Sandwich it between two blocks of wood.

 

The early blocks and heads apparently had dead zones in the coolant passages that didn't flow much coolant.  This lead to hot spots.  The later design is probably just meant to keep cooling flowing at the rate that the pump could pump it and well-distributed.  If your pump does 10 gallons per minute and you have passages for 50, you won't get good flow distribution.

 

So, you could even consider improving the flow distribution in the head.  But you'll have to make educated guesses.  Too much knowledge to be comfortable now.

[redzedsled]

For clarity...

Yes, this is the section where the passages are blocked.

[Zed Head]

See reference pics below showing ring dimensions.

 

Aftermarket generic head gasket at top and original head gasket off E31 head at bottom.

 

Nissan superceded to 11044-27L00 and 11044-27L01 most likely because of the size this oval ring.

 

The only issue is the Datsun 810 and early Maximas gaskets dont have the same cooling holes as the original gasket.

 

DSC01819.JPG  DSC01820.JPG

 

DSC01825.JPG  DSC01826.JPG

Seems like this would be the match.

[redzedsled]

After downloading the Stone Gasket Catalog online, the profile of their gasket for the L24 is part number JA-01067, which is exactly like the gasket I have from the regrind kit.

 

This gasket supercedes part numbers 11044-U8720 and 11044-27L00 respectively. The L24S, and L24E engines on select models also use this gasket.

 

Whatwith depleting Genuine Nissan engine parts available we are at the mercy of the aftermarket companies who are making one size fits all gaskets it seems.

 

Or does Nissan have pure logic in mind when blocking off some water passages from the block to intently restrict water flow as some have suggested.

 

It seems that the L24 blocks after the 240Z era began to utilize less cooling passages up through the block to the head to support this notion.

 

This is noted in the image of the 280Z block where fewer holes are running vertically though the block and into the head.

 

Is the firing ring size more important than the distribution of cooling through the earlier L24 blocks according to the gasket maker Stone in this case.

 

Often with Nissan supercessions, parts and their fitment can become lost in translation, and Nissan parts support centers here in Canada are not very helpful.

 

This issue will arise for more Datsun 240Z owners as they try and locate the correct head gasket for their restoration.

 

I see many of this type of new design gaskets being purchased online, so I hope to see more thoughts and insights.

[siteunseen]

My '77 2.8 block runs way cooler than both of my 2.4 blocks but there's some differences other than water passages.  Temp sensor in the thermostat housings are different as well as the temp gauges in the 240s.  The 280s have bigger radiators, plus fan shrouds.

 

Everything I've read about other 240s is the excessive needle reading towards the hot side.  Could be older gauges or newer blocks?  Good question. 

[LeonV]

My '77 2.8 block runs way cooler than both of my 2.4 blocks but there's some differences other than water passages.

 

Did you check that with a thermometer?

[siteunseen]

Did you check that with a thermometer?

My orange one with the 280 radiator and shroud reads 176.  I'll check the 280 tomorrow and let you know.

[madkaw]

Revisting the oval/round fire ring aspect. The perfect round fire ring type HG should be avoided for the fact that most head rebuilts include installing larger valves that WON'T likely clear that type gasket, or clear your cylinder bore for that matter. Any unshrouding work would also make that HG useless. 

[redzedsled]

Steve, although I am running stock valves, another consideration is the use of over-sized pistons.

 

If you use over-sized pistons like most would during a rebuild, it also makes the head gasket even closer to the firing ring edge.

 

The stock bore is 83mm, and with say a 40 over piston it brings the bore up to 84mm.

 

With a stock factory firing ring measuring 85mm x 89mm, that only leaves a 0.5 mm clearance around the head gasket in some areas.

 

Just another observation I had along the way. A larger firing ring would provide more clearance, but how much does it affect compression.

 

The later 260Z and 280Z head gaskets at least don't block the cooling holes coming up from the block.

 

Still torn and have to make a decision quick whether to use the Stone head gasket!

[siteunseen]

Revisting the oval/round fire ring aspect. The perfect round fire ring type HG should be avoided for the fact that most head rebuilts include installing larger valves that WON'T likely clear that type gasket, or clear your cylinder bore for that matter. Any unshrouding work would also make that HG useless. 

So using a 280 HG on a worked E31 head on top of a 2.4 block, one could avoid these issues (other than the block notching)?

[redzedsled]

So using a 280 HG on a worked E31 head on top of a 2.4 block, one could avoid these issues (other than the block notching)?

To be honest, I never really explored the larger valve option, so I really couldn't comment on the block notching.

 

You bring some very interesting points in your discussion though.

 

If the larger firing ring doesn't affect compression too badly, then may be the 280 HG would be the answer.

[madkaw]

What i am saying is that the oval shaped fire rings are big enough for the larger exhaust or intake valves to be intsalled. Most HG's have the oval shape already. It seemed the OP was concerned with getting a perfectly round fire ring on the  HG . Well that might not work for anything other than stock. The only way to be sure is to lay the HG on the head to make sure it doesn't impede into the combustion chamber.

If you have your "how to modify" book, look in there. The oval fire ring allows for some nice unshrouding which is strongly recommended on the L24. Cliff-you shouldn't use a 280 Hg