Combustion Chamber Volume Check.

Several decades ago, (Early 80’s) when I was quite new to things Lotus, someone asked the following question.

Could you tell me what the CC volumetric capacity of the combustion chambers of the twin cam cylinder head is on your engine?

My dumb newbie answer was… I dunno… what’s CC capacity mean anyway?

And that’s when the learning journey began.

Fast forward to recent times, I now fully understand what checking the CC volume capacity of each chamber means, and how to go about checking the capacity and the simple tools and equipment required, a scientific method will provide accuracy within .1 or.2 of a CC. (Cubic Centimetre)

This particular process will eliminate any guess work, and provide the required results and data you need to build a better performing engine if undertaking a self build, or, pass the data onto your engine builder, if you are farming the engine build out to others.

Your engine builder could also do this work for you if you want, but it will cost you money, because it is a slow and laborious process, so, this is why I wanted to share this money saving information with you.

We have made a series of videos to explain the DIY method of checking the CC or (ML-Millilitre) chamber capacity.

By now, most of the original twin cam cylinder heads have been skimmed or surface machined, many are now under the recommended thickness of 4.600 inch, or 116.84mm, and after several surfacing operations, that also means the chambers will no longer be the correct capacity, which will have an influence on the resulting compression ratio.

You need to know all of the data to dial things in and achieve correct settings when building a new engine.

The first (Part 1) video is below, if you are new to this process, then you will glean much from what we show and reveal.

Combustion Chamber Pt 1 – Tools and Setting Up.

Combustion Chamber Pt 2 – Using the Burette to measure combustion chamber volume.

Extra notes: With each chamber volume measure, don’t forget to write down or record the results, just make up a simple table ona sheet of paper denoting each chamber, number them 1 to 4 and you are good to go, and record the date of the test.

Also record other details of the cylinder head, such as the serial number, measure and record the thickness or depth of the head, to see if it varies from what the original measurement is.

Combustion Chamber Check Pt3 – Comparing Std Stromberg Combustion Chamber Capacity.

Tools:
There are plenty of online science lab suppliers, the writer bought a low cost polycabonate burette, it works just fine, also purchase with the burette the special holding clamps, the writer nearly didn’t include the clamps in the order, but glad he did as they are worth their weight in gold.
The special support stand and base was DIY made, the base consisting of  a lump of scrap steel, 100mm Dia X 60mm thick mild steel bar, with a drilled and threaded hole, the tall rod for the support stand was a length of mild steel rod 1/2″ dia, threaded and screwed into the base.
Set it all up on the bench and the volume testing can begin.