Hello Listers:
I have begun tearing down the engine on my '49 TC EXU # 7715 w/matching engine # XPAG 8504. The cylinder head #22952 has the production date 26A8 (January 26, 1948) so I believe that it is also original to the car. The head has been modified with larger 34 mm exhaust and 36 mm intake valves. These are the same valves that Moss Motors calls out as standard for the TD Mark II, 1500 cc engines. The intake support posts have been contoured for better breathing and the head has been nominally shaved.
After removing the cylinder head I took a quick measurement of the cylinder bores and to my surprise got a reading of 2.833". Even more surprising was to find the top of the pistons marked "std". I know that the standard bore on the XPAG engine is 2.618". The largest overbore pistons available from Moss are +.120" which would result in a cylinder bore that would be 2.738". These existing cylinders are +.100" over the largest oversize pistons available for the XPAG engine.
According to WKF Wood manual, the stock XPEG engine has a bore of 2.8346".
Question #1: Is it possible that a prior owner could have had XPEG sleeves installed in this XPAG block and then used "std" pistons called out for the XPEG 1500 engine?
Question #2: If so, is it safe to overbore the existing sleeves using +.020" pistons for use in the XPEG 1500 cc engine?
Question #3: Or... could the PO have had XPAG sleeves pressed in and then bored them out enough to accept std sized XPEG pistons without breaking through the sleeves?
Question #4: Could I have this block re-sleeved using XPAG cylinder liners and then install std XPAG pistons or will the XPAG sleeves be too small for the larger existing bores?
Craig Siler
'49 TC EXU 7715
'47 TC 2208