Datsun Roadster Forum-311s.org

Not sure exactly where to post this so I will start with it here. After not finding an easy solution to head gaskets to work with 90+mm bores on the U20 I am building up, I have talked to SCE Gaskets and will be having some of their ICS Copper gaskets custom done. Info can be found here. https://www.scegaskets.com/hrf_faq/ics- ... tallation/ The gaskets will be fine for both normally aspirated and forced induction applications. These will be a one time run and if anyone is interested, I will be glad to add a few extra in, cost would be US$150 plus shipping. If there is enough interest so they are doing 15+, pricing will drop. Delivery would be in early Feb.

Before I had my Arias pistons machined a bit more to reduce an overly high compression, I strongly considered trying a copper gasket. However, I was not able to find one that was 1) new and 2) thick enough to make the targeted compression drop. (As an aside, there are also other factors to consider when chasing detonation that are discussed on various sites in regards to "quench" that can change by using different gasket thicknesses that can effect (and possibly increase) the likelihood of detonation even while dropping compression).

How thick will these gaskets be? Reusable? It's very nice that they don't require an o-ring.

Curious as to what displacement this engine you're building will be? Look forward to hearing more about the build if you want to share!

We do currently have a few copper head gaskets in stock for both U20 up to +.040" and R16 up to 3.5" bore at .093" thickness. No o-ring required, re-usable.

Larger bores are not a problem either, just specify what you need. They do not take long.

In general we don't really recommend thicker gaskets, (thicker heads are virtually always a better plan), but made these due to customer requests.

R16 shown. We may add an o-ring at the oil passage as extra insurance, but these do seal ok if the surface is prepped correctly.

What kind of pricing do you have on the gaskets?

Good to know JT, was not aware!

I was at UHauls engine repair center as tech line operator and warranty clerk .... they had/ put brass shims on trucks under the gaskets ...they decked the head ,shinny new , used dots of aviation gasket sealer and copper coat because customers never bought premium gas
My 83 Audi 5000 turbo diesel had a fiberglass head 3 different sized gasket in layed with steel core and neoprene gasket

Gregs672000 wrote: ↑Fri Dec 24, 2021 9:24 pm Before I had my Arias pistons machined a bit more to reduce an overly high compression, I strongly considered trying a copper gasket. However, I was not able to find one that was 1) new and 2) thick enough to make the targeted compression drop. (As an aside, there are also other factors to consider when chasing detonation that are discussed on various sites in regards to "quench" that can change by using different gasket thicknesses that can effect (and possibly increase) the likelihood of detonation even while dropping compression).

How thick will these gaskets be? Reusable? It's very nice that they don't require an o-ring.

Curious as to what displacement this engine you're building will be? Look forward to hearing more about the build if you want to share!

We are shooting for something in the .040-.055 range (actual thickness will be determined by the engineering guys), the gauge of implanted sealing ring in the gasket and the clamp force between the head and block that we are shooting for determines finished sizing. Technically you could reuse them but the sealing compound on the gasket around the water jackets and oil passages are only good for a one time install, any reuse would require some sort of sealant. I am not planning to reuse mine, if I tear the motor down, I will use a fresh gasket. They also are not as finicky about surface finish to get a good seal.

Displacement should be in the 2150cc area. Running KA pistons, with a set of LouM's long (R16) H beam rods, we may offset grind the crank a touch for a little extra stroke but will have to wait to see how all the parts measure up. Head will have stock valves with mild port clean up and unshrouding the valves, cam is a LouM spec grind, Building a long tube header for it and at least initially will be running Mikuni HSR carbs though will probably go with EFI eventually.

Respectfully, if you haven't already bored the block, you might re-think this direction. If you have bored the block that is pretty much the last waltz for that particular block.

We sell pistons up to 89mm (not 90) specifically to avoid all the issues you are running into. At 89mm (3.5") the Nissan HG works perfectly, and it is hands down the best gasket available.

At 89, you could go to 89.5 if there was really a need and the power difference at 90 vs. 89 sure isn't worth the hassle or risk.

At 90mm you have pushed the bore to the max and some blocks have failed completely at that bore. There is just very little left of the cylinder walls. Hope you had the block checked with ultrasound if you did bore it already. Guessing the motivation is to use the cheap KA pistons? It's pretty messy when a cylinder wall lets go.

Word to the wise, many times it's best not to be on the bleeding edge by pushing bore to the absolute limit unless the engine is considered a throw-away.

In all cases we recommend using the Nissan HG if possible. Nissan got it right with the current generation of gaskets-pretty much trouble free.

JT, thanks for giving your opinion but this build has been VERY well planned. Going "cheap" is not a motivation on this build for the pistons or any other item going into it. I have had multiple blocks ultrasound tested and the best one was selected for this build. You are correct this is the ragged edge for wall thickness but with the right block it is fine. The KA pistons were picked as they allow the use of a longer rod NOT because they were cheap.

The engine spec I am building has been done before a number of times with no issues and if it goes bang, it goes bang. Thats what track cars do on occasion......and if it happens, I will build a different configuration for the next one.

You are correct Nissan really did do a good job on the head gaskets and would use one if it would work. The gaskets, I am having done, should seal as well and definitely better than available options.

Sounds good, I didn’t realize it was a track car. As you say, in that case it doesn’t really matter, and it’s good you had a few blocks to choose from.

That being said, GOOD u20 blocks are getting scarce, hate to see one get bored to 90mm if usable at a “less final” bore. For a track car, cast KA pistons would not be a great choice, but forged would hold up fine. KA cast pistons tend to grenade when pushed too hard- I’ve owned seven 240sx over the years, so lots of ka24 experience, Best of luck with your build!

25 years ago I had sent the R16 & U20 factory head gasket's to a company called Copper gaskets unlimited to be patterned. It was owned by Mike Malone SR., his son Mikey and Mother Verna who took it over after Seniors death. I don't know if she is still running it or who runs it now as I lost touch with them when I opted for the thicker composite gaskets with fire rings that we sold for years. The all copper gaskets were around $80.00 then, but with the rise in copper costs I imagine they must be over $100.00 easily. A quick search on the internet I found this: https://coppergaskets.us/
Ed Johnson used them also and we came up with the annealing procedure "installer instruction sheet" that actually worked better than the companies instruction sheet. I would contact them to see if they still have the patterns. At the time I had dealt with them they had one price for everyone. They also will set the bore diameter on the gasket to whatever size your pistons are.

Dean
(Asptj)