|
Sponsored Links (Register now to hide all advertisements) |
|
|
Thread Tools | Display Modes |
06-30-2022, 08:19 PM | #1 |
Member
Join Date: Jun 2010
Posts: 95
|
model B piston clearance in the block
when you bore a new cylinder, what should the clearance be for the piston? Thanks, steve
|
06-30-2022, 08:36 PM | #2 |
Senior Member
Join Date: May 2010
Location: Wa.
Posts: 5,409
|
Re: model B piston clearance in the block
|
Sponsored Links (Register now to hide all advertisements) |
|
06-30-2022, 09:23 PM | #3 |
Member
Join Date: Jun 2010
Posts: 95
|
Re: model B piston clearance in the block
clearance between piston and cylinder wall on a new bore steve
|
06-30-2022, 09:33 PM | #4 |
Senior Member
Join Date: May 2010
Location: Santee, California
Posts: 3,505
|
Re: model B piston clearance in the block
Pete gave you the proper answer.
|
06-30-2022, 09:36 PM | #5 |
Member
Join Date: Jun 2010
Posts: 95
|
Re: model B piston clearance in the block
.o30 pistons nos , no info
|
06-30-2022, 10:02 PM | #6 |
Senior Member
Join Date: Jun 2010
Location: 34.22 N 118.36 W
Posts: 1,057
|
Re: model B piston clearance in the block
Sponsored Links (Register now to hide all advertisements)
Depending on the design, the proper clearance can be .003-.010 J
__________________
As Carroll Smith wrote; All Failures are Human in Origin. |
07-01-2022, 05:55 AM | #7 |
Senior Member
Join Date: Jan 2012
Location: Western North Carolina
Posts: 3,903
|
Re: model B piston clearance in the block
The clearance is measured at the points cross wise in the engine (side to side not fore and aft). The pistons are ground eccentric so that the clearance fore and aft is greater. This allows for expansion of the piston. That applies to a piston with a full skirt. The clearance in the side to side direction will be about 0.004.
For pistons that are ground round (don't use these) the clearance is greater, perhaps 0.010. For pistons that have only a partial skirt (slipper pistons), like Egge pistons, the clearance can be less, and I don't know what it should be. As Pete said, use the recommendation of the piston manufacturer. If not supplied with the pistons, contact them to get their recommendation.
__________________
A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. |
07-01-2022, 06:02 AM | #8 |
Senior Member
Join Date: May 2010
Location: Largo Florida
Posts: 7,225
|
Re: model B piston clearance in the block
Yep, what Pete said.
A general rule of thumb is .001" per inch of bore. And I think loose is better than tight. |
07-01-2022, 08:15 AM | #9 |
Senior Member
Join Date: May 2010
Location: Long Island, NY
Posts: 3,472
|
Re: model B piston clearance in the block
The November 1932 Service Bulletin, Page 66, indicates the fit for aluminum alloy split skirt pistons is 0.0005" to 0.0025".
__________________
Bob Bidonde |
07-01-2022, 10:03 AM | #10 |
Senior Member
Join Date: May 2010
Location: So Cal
Posts: 8,755
|
Re: model B piston clearance in the block
|
07-01-2022, 11:31 AM | #11 |
Senior Member
Join Date: Jun 2010
Location: Temecula, CA
Posts: 4,091
|
Re: model B piston clearance in the block
Don't use the info above! This was for pistons with a full split skirt, not like todays pistons. I usually bore to .003" and hone another .0005" looser is better than too tight! Racing pistons are a different story, and require much more clearance. Too tight will result in scouring of the pistons and walls, you don't want this.
|
07-01-2022, 11:44 AM | #12 |
Senior Member
Join Date: May 2010
Location: Oregon
Posts: 1,375
|
Re: model B piston clearance in the block
Regarding the quote from nkaminar in Post #7: "For pistons that are ground round (don't use these) the clearance is greater, perhaps 0.010"
I wonder what is wrong with concentric ground pistons? I know it is old technology but I have pulled this type of piston from old engines that had an apparently long and useful life. These were also split skirt pistons which were set up much tighter than the 0.010 inches cited. |
07-01-2022, 01:39 PM | #13 |
Senior Member
Join Date: May 2010
Location: Eastern Tennessee
Posts: 11,520
|
Re: model B piston clearance in the block
Steve, have you actually measured the pistons? Often times, I find that pistons are generally manufactured in a (under)size so when the cylinder is bored (-and then honed) to the nominal oversize, the correct amount of clearance the manufacturer desires is there.
|
|
|
Sponsored Links (Register now to hide all advertisements) |
|