ACF cylinders

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flat38
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Re: ACF cylinders

#16

Post by flat38 » Tue Nov 26, 2019 2:48 am

I must eat a bit of crow here. I reported that my cylinder bores were egg shaped by .020". I was using a new bore gauge and when I remeasured yesterday I realized that I read .002" as .020". The gauge is marked 10, 20, 30 etc. and I misread it. I will not need to re-bore, but I do need to cut the base flange to be square to the bore and remove about .050" from the deck to get proper squish. I have made a tapered mandrel for the cylinder bore and will turn it between centers.



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Re: ACF cylinders

#17

Post by Buddhahoodvatoloco » Tue Nov 26, 2019 8:43 pm

It's not Crow hombre, it's a admirable manning up. Kudos :lol:
flat38 wrote:
Tue Nov 26, 2019 2:48 am
I must eat a bit of crow here. I reported that my cylinder bores were egg shaped by .020". I was using a new bore gauge and when I remeasured yesterday I realized that I read .002" as .020". The gauge is marked 10, 20, 30 etc. and I misread it. I will not need to re-bore, but I do need to cut the base flange to be square to the bore and remove about .050" from the deck to get proper squish. I have made a tapered mandrel for the cylinder bore and will turn it between centers.

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Re: ACF cylinders

#18

Post by Raytag » Wed Nov 27, 2019 9:35 am

flat38 wrote:
Tue Nov 26, 2019 2:48 am
I must eat a bit of crow here. I reported that my cylinder bores were egg shaped by .020". I was using a new bore gauge and when I remeasured yesterday I realized that I read .002" as .020". The gauge is marked 10, 20, 30 etc. and I misread it. I will not need to re-bore, but I do need to cut the base flange to be square to the bore and remove about .050" from the deck to get proper squish. I have made a tapered mandrel for the cylinder bore and will turn it between centers.
I`ve zero knowledge about flatties
We`re talking castiron barrels aren`t we ? .002 ovaled ? Do you intend to straighten the bore with a hone?
Would love to see that mandrel.

Ray

flat38
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Re: ACF cylinders

#19

Post by flat38 » Wed Nov 27, 2019 11:56 pm

Yes, they are cast iron. The out of round is only at the bottom of the bore and the small part is the same as the rest of the cylinder. I will most likely touch it up with a fine stone as the clearance is less than I would like. It is .003" and I would like .0035 to .004". There are also some deep hacks from pulling the roughing hone out too fast at the top of the bore. They need to be smoothed out a bit. I will try to post a pic of the cylinder on the mandrel when I have it in the lathe.

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Re: ACF cylinders

#20

Post by Larry » Thu Nov 28, 2019 2:58 pm

Does the cylinder become round when the base is torqued?

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Re: ACF cylinders

#21

Post by RooDog » Thu Nov 28, 2019 3:39 pm

Larry wrote:
Thu Nov 28, 2019 2:58 pm
Does the cylinder become round when the base is torqued?
Very good question. Perhaps all this work , except squaring the base to the bore, should be done with both base and head torque plates, another added expense....
....RooDog....

flat38
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Re: ACF cylinders

#22

Post by flat38 » Thu Nov 28, 2019 7:58 pm

I have both base and head torque plates and they will be used when I hone the cylinders. Whether or not torquing the base will make the bore round is not a concern at this point as the bases need to be trued to the bore. The smallest part of the out of round condition is the correct bore size and is only at the bottom below the base flange. it does not concern me as this will only see the skirt of the piston anyway.

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