HC-E Oversized Head Gasket

Hi folks!

I recently posted a topic in Q&A about off-the-shelf MLS head gaskets (HG).
We concluded that the off-the-shelf option doesn’t exist and that if one were to go the MLS path, it would be a custom job.

This brings me to another question;
What about oversized composite head gaskets?

The reason for all these HG questions are this
I’ve had my block re-bored by 0.50mm with new pistons. Now my composite HG is overhanging the bore and is misaligned on some bores.
I’m no mechanic, but I’ve done 2 university years of motorsport studies and numerous readings on engine dynamics to know that the HG bores should always be slightly larger than the cylinder bores.

Anyone have personal experience with this issue?

I have come across this problem with E series engine’s in particular I bored out my current engine to 72mm from 66.6 to take ejde piston’s from there the ef/el and ed10/20 head gaskets were too small in the bores to fit. The solution for Myself and anyone else that has done this was to use the ejde head gasket which had the benefit of being mls also. I just wonder if the hd-e or the he-e gaskets may be a bit larger considering they are the bigger engines in the H series? or is the bore size the same?

The bore sizes are the same across all the H series, the stroke differs though.

Good to know I’m not the only one with this issue!

After interrogating my machinist, he has informed me of a head gasket manufacturer in VIC:
Ridgecrest Engineering

Conclusion: For a re-bored block, a custom gasket (copper or MLS) is the only appropriate head gasket for the H series engine if the re-bore is more than +0.5mm. Approximate cost; AUD $110-$130 (Depending on thickness)
This applies to those in Australia looking to source local parts.

I hope this info helps other people.


I have a collection of old head gaskets (various brands) - some of them are 76.5mm bore and others are 77mm. The 77mm version would no doubt be fine on your 0.5mm oversize pistons.

Have a look at the link below for some options:



77mm is what I need for sure. I’ve gone with the copper head gasket this time (thickness=1.2mm), but that’s a great link!
(At AUD$70 after shipping that’s very good)
Your post will be the new answer for this question. :grin:

Edited my last post

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