Ah thanks cooperman,Our old A-Series engines do thrive on higher compression ratios. I would suggest that you skim the head to achieve around 9.8:1 and if using an Evo001 cam you go for an Aldon Yellow distributor. (That cam is great for mid-range torque and I am just fitting one to a 1293 cc MG Midget).
Before skimming the 295 head, check the depth of the oil way hole and ensure that you have a minimum of 0.050" (fifty thou) remaining depth after skimming. With the larger capacity it's unlikely you will need to skim anywhere near to the minimum in order to get the CR you need. Slightly bigger inlet valves would be good, but not essential.
Yes, check the rocker angles after skimming, but I think that you will not need to shim the rocker pillars, but make sure the rocker pads onto the valves are OK.
Measure and calculate accurately and all will be fine. Come back on here if you need any further advice.
Some say that you can't rev a 1098 engine, but they are fine up to around 6,000 rpm. I once had an MG 1100 engine with the old 731 cam in a rally mini and I regularly used over 6000 rpm. It never blew up.
I've just checked my oil feed depth and it's 2.60" into the head. My head height is 2.73" suggesting a 20thou skim already. I'm not sure if I've measured that right because that would effectively give me 0.13" from the end of the feed to the cylinder surface. Implying I could shave a right chunk off? 80thou
Theoretically, as 20thou has reduced the cc to 26cc then that would roughly suggest that another 60thou skim would achieve a reduction in 4.5cc. Giving me 21.5cc. With all measurements taken into consideration that would get it to 9.6:1
Obviously this is a rough estimation. Which I'm not keen on, so I'll get the graph paper out first and work out the surface area to cc before I get anything done.
Cheers Babs
Edited by babsbrown, 30 November 2024 - 06:41 PM.
