The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Miker on 11.09. 2020 08:32
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I have measured the bores on my barrel with a micrometer and they seem to read average 2.771" or 70.3834. Allowing for piston clearance would that be standard or +020" . Trying to figure out what next size up pistons to buy. *conf*
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What is the reading for the Most worn part ? ( 1/2" or so from the top, front to rear) The size you have would seem to be a worn 0.010 O/S
Or a really flogged out STD. 70.5mm would be +0.020"
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G'day Miker.
70.500mm is +20 thou. Double check your measurements and the accuracy of your measuring sticks.
1mm = 0.0393701"
Cheers
ironhead beat me.
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Now that you mention it the cases did have +010" pistons in them but I have a few barrels that came with all the parts and wasn't sure if this barrel was from that engine. If that is right would I be able to go +020" assuming my measurements are right(I will take it to an engine place to get it double checked) There is a slight lip at the top and minor surface rust. What is the clearance for 7:25:1 pistons?
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G'day Miker.
The piston manufacturer normally quotes the clearance required. Modern material pistons require a little less than the originals. 2 to 3 thou with solid skirt pistons should be OK, 1&1/2 thou for split skirts.
Cheers
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dunno what happened to my post - I'll try again....
.060" is roughly 1.5mm. Your bore @ 88mm is 3mm oversize, or 1/8" (.125 ins)
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dunno what happened to my post - I'll try again....
.060" is roughly 1.5mm. Your bore @ 88mm is 3mm oversize, or 1/8" (.125 ins)
Who’s got an 88 mm bore?
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https://en.wikipedia.org/wiki/8.8_cm_Flak_18/36/37/41
An anti-aircraft gun like this one maybe?
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TT / groily - dunno what's going on here. Originally I was replying to a post about 'what barrel do I have' or similar, where someone said std was 85mm but their barrel was 88mm. Then my reply disappeared and I ended up on this post. Summat strange going on ..........