Pre HE engine to HE Engine

Just thinking out aloud here - what is involved in making a Pre HE engine into a HE engine? None US Spec. Ignoring ancillaries with the core engine itself, is it just the complete heads and pistons, or does it go further to things like conrods, timing gear etc.



I did this on my first E-type. Best is to replace pistons AND sleeves along with the heads. Note that HE and pre-HEAD gaskets differ, so you need to fit HE head gaskets with the HE heads.

The result (which included converting to EFI) was very impressive, but I maintain that a transmission with a deep overdrive top gear (0.7 or less) is worth far more than pre-HE to HE conversion.

That’s assuming both engines are 5.3 litre.

kind regards

So what was the reason for replacing the liners? Best practice or there is a need for a HE engine.

Yes looking at the gearbox overdrive arrangement as a separate issue.

Thanks for the input.


Yes both would be 5.3 - if i wanted to replace with a 6 litre, it would be cheaper to just source a whole engine rather than modifying a 5.3 to a larger capacity.

You might be surprised how worn your bores are. HE (hi comp) engines can be dirty if the bores aren’t perfect, lots of blow-by.

What impressive results did you get? I have this half-baked idea to convert a 6.0 liter I have laying around to using the Heron-type chambers of the pre-HE. This means getting pistons with the appropriate dish and compression height. I have possibly found the pistons already, 3 sets of them actually, because they are really made for the Chevy 2.0 liter 4-cylinder as was found in the Lumina, Corsica and S-10 pick-ups, etc. Piston pins are the wrong size, though. They were too cheap to pass up and are probably no longer available, but I’ve done nothing beyond that and haven’t even broken down the 6.0 since getting it 25 years ago.

My E-type was able to keep up with an XKR 4.2L.

I should add, that I had a std exhaust with a light weight alu flywheel. The engine was EFI’ed , using XJS hardware, with Megasquirt2 for mapped fuelling and dissyless timing.