Chamfering the bottom of cylinders.

General engine tech -- Drag Racing to Circle Track

Moderator: Team

LSP
Pro
Pro
Posts: 362
Joined: Tue Mar 16, 2010 12:33 pm
Location: Charlotte

Re: Chamfering the bottom of cylinders.

Post by LSP »

Disassemble the motor, put about a .050"-.060" radius at the bottom of each cylinder, rewash thoroughly and reassemble.

Doing otherwise may risk having the motor disassembling itself, without your consent.
j-c-c
Guru
Guru
Posts: 6545
Joined: Sat Sep 03, 2016 9:03 pm
Location:

Re: Chamfering the bottom of cylinders.

Post by j-c-c »

MTENGINES wrote: Wed Mar 07, 2018 6:05 am
j-c-c wrote: Tue Mar 06, 2018 10:22 pm Does a sharper edge vs any radius wipe any splashed oil off skirts better and with a more favorable result?
Yes the sharper edge does a better job at wiping oil, along with aluminum from the piston.
So maybe a visible test for this would be in the case of a sharp edge removing any piston skirt coatings?
User avatar
MadBill
Guru
Guru
Posts: 15024
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: Chamfering the bottom of cylinders.

Post by MadBill »

We should keep in mind that the protrusion is less than 3/16"; it's not like the wrist pin is coming into view... :-k
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.
Berserk
Member
Member
Posts: 60
Joined: Sat Jan 09, 2010 12:17 pm
Location:

Re: Chamfering the bottom of cylinders.

Post by Berserk »

The edge does not feel sharp.
peejay
Guru
Guru
Posts: 1946
Joined: Tue Aug 10, 2010 9:16 pm
Location:

Re: Chamfering the bottom of cylinders.

Post by peejay »

MadBill wrote: Wed Mar 07, 2018 5:08 pm We should keep in mind that the protrusion is less than 3/16"; it's not like the wrist pin is coming into view... :-k
That is what I am thinking.... it is not like some strokers I've seen where half the piston is falling out of the hole.

And an inadeqately chamfered cylinder in one of those will do a very fine job of removing metal from the thrust face of the skirt!
groberts101
Guru
Guru
Posts: 1980
Joined: Sat Mar 08, 2008 3:08 pm
Location: Minneapolis

Re: Chamfering the bottom of cylinders.

Post by groberts101 »

It's all relative to the skirt design/length and where that particular pistons gauge point was designed/located. Some very short skirt pistons gauge points can be damned near the bottom of the skirt. What's the specific part #? Look up the spec's or call the mfgr.

Then add the potential for a lower gauge point with the fact that the bottom of the bore has not been radiused on major minor thrust and you can easily score skirts and bore during cold starts. As things wear out it doesn't usually get any better either. Just imagine how that cold piston flops around when the motor goes vroom on every startup.
Post Reply