239 Oversize piston?
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From: Detroit Lakes, MN
239 Oversize piston?
I have started working on the motor of my 52 F2 and found that that one piston had a chunk missing out of it and left a big dimple at the top of the wall. The bores are already over by .040 and I am hopefull that the bores clean up to +.060 but in the event they dont I know sleeving is an option but has anyone ever put larger like +.080 pistons and if so who sells them?
Thanks, Scott.
Thanks, Scott.
Fleet Owner
Joined: Jul 2004
Posts: 27,288
Likes: 1,053
From: NM
"Back in the day" folks seeking big cubic inches would bore earlier flatties all the way to +.125". Plenty of them at +.080". With later 8BA's you'd be wise to have the bores sonic-checked for wall thickness before going too big. Minimum wall after boring should be 0.100", as I recall, for a street motor.
Egge and many others offer all kinds of pistons in many O/S's. You can still find OEM Ford piston sets at the major parts houses like JobLot, Dennis C., and more.
Sleeving the one cylinder might be the way to go if the rest of the bores clean up at .060", but sleeving a flatty is different than sleeving an OHV. The head won't clamp the sleeve all the way around, because of the transfer area between the cylinder and the valves. The proper methods for sleeving them may not be understood by modern machine shops, so I'd hope for a simple bore taking care of it.
Egge and many others offer all kinds of pistons in many O/S's. You can still find OEM Ford piston sets at the major parts houses like JobLot, Dennis C., and more.
Sleeving the one cylinder might be the way to go if the rest of the bores clean up at .060", but sleeving a flatty is different than sleeving an OHV. The head won't clamp the sleeve all the way around, because of the transfer area between the cylinder and the valves. The proper methods for sleeving them may not be understood by modern machine shops, so I'd hope for a simple bore taking care of it.
Fleet Owner
Joined: Jul 2004
Posts: 27,288
Likes: 1,053
From: NM
I've posted a request on the Flathead forum to gather info on it. On OHV engines, they machine a lip onto the top of the cylinder so the head clamps the sleeve in place. Can't do that on a flatty. When the cylinder was cracked and leaking coolant, you need to use a sealant that also locks the sleeve in place. I don't remember all the details; hopefully the flathead gurus will chime in and give details. Guys on the Ford Barn probably have this info too. My block is blessedly free of cracks and scratches so honestly I didn't pay a whole lot of attentiion when it was discussed years back.
Fleet Owner
Joined: Jul 2004
Posts: 27,288
Likes: 1,053
From: NM
Here's what I've gotten so far:
Many of the stock sleeves used the upper flange (certain early '30's blocks were sleeved from the factory, not 8BA's). When repairing a non-sleeved block , always leave a shoulder at the bottom of the cylinder bore to press the new sleeve down against, when boring the wall to accept the sleeve. The type of sealant isn't a critical issue, not necessary at all, unless the sleeve gets wet (i.e., cracked cylinder wall). Usually chill the sleeve and install quickly, but many have been done with brute force.
More as it comes in......
Many of the stock sleeves used the upper flange (certain early '30's blocks were sleeved from the factory, not 8BA's). When repairing a non-sleeved block , always leave a shoulder at the bottom of the cylinder bore to press the new sleeve down against, when boring the wall to accept the sleeve. The type of sealant isn't a critical issue, not necessary at all, unless the sleeve gets wet (i.e., cracked cylinder wall). Usually chill the sleeve and install quickly, but many have been done with brute force.
More as it comes in......
