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working out compression ratios
#17
(08-10-2018, 08:28 PM)JonE Wrote:
(30-09-2018, 02:39 AM)Tony Press Wrote: The standard Compression Ratios seem to be

1923-1933 4.8 (or 4.9) to 1

1933-1936 5.2 ? to 1

Having observed the depths of the cavities of the early LC head for the priming arrangements, does the increase in compression ratio essentially come down to the effects of their removal? I didn't think they went on as long as 1933...


Under the post Head Identification I wrote-

I think this is the progression after reading the cards and parts books -

The earlier low compression head with tap primer plug holes was 1A 38 (Part No BC 28)

The primer holes were deleted, but other than the parts listings deleting the plugs there wasn't a change in the part number or casting number shown on the cards for this later style of 'low compression' head up to 1933.

(no mention of a higher compression ratio at the removal of the priming plugs)

Casting number 1A 670 was introduced under Part Number BC 82 in August 1933 with a slightly raised compression (5.2?) .

(the cards specifically mention this higher compression ratio)

Casting number 1A 684 for BC 82 appeared sometime before 1936 (not sure of the change here but it is listed for the three bearing engine ?). 

In 1936 head number is listed as 1A911 - the new so called 'high compression' with two bolt water outlet.

Out of interest the later head gasket is shown as 1A 912 Klingerite or 1A 915 C/A.
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Messages In This Thread
working out compression ratios - by JonE - 29-09-2018, 02:20 PM
RE: working out compression ratios - by Chris KC - 29-09-2018, 03:35 PM
RE: working out compression ratios - by JonE - 29-09-2018, 06:28 PM
RE: working out compression ratios - by jansens - 29-09-2018, 10:43 PM
RE: working out compression ratios - by jansens - 30-09-2018, 07:12 AM
RE: working out compression ratios - by JonE - 08-10-2018, 08:28 PM
RE: working out compression ratios - by Tony Press - 08-10-2018, 11:44 PM
RE: working out compression ratios - by jansens - 30-09-2018, 11:14 AM
RE: working out compression ratios - by JonE - 30-09-2018, 12:34 PM
RE: working out compression ratios - by jansens - 30-09-2018, 08:57 PM
RE: working out compression ratios - by JonE - 01-10-2018, 08:59 PM
RE: working out compression ratios - by GK5268 - 08-10-2018, 10:00 PM
RE: working out compression ratios - by JonE - 09-10-2018, 09:39 AM
RE: working out compression ratios - by JonE - 10-10-2018, 08:53 PM
RE: working out compression ratios - by JonE - 12-10-2018, 11:04 AM
RE: working out compression ratios - by JonE - 11-10-2018, 07:36 AM
RE: working out compression ratios - by jansens - 11-10-2018, 08:14 AM
RE: working out compression ratios - by JonE - 11-10-2018, 10:00 AM
RE: working out compression ratios - by jansens - 11-10-2018, 10:17 AM
RE: working out compression ratios - by Dave Mann - 11-10-2018, 10:23 AM
RE: working out compression ratios - by Dave Mann - 11-10-2018, 08:30 PM

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