The Ford Barn

Ken/Alabama · 12-07-2011, 02:33 PM

Anyone know how far you can bore the later V-12 blocks ? I have a 46-48 V-12 with 2 7/8" bore and want to bore it to 3 1/16 and use Ford pistons. That would be .187 overbore. I have a couple of V-8s that big but not sure about the V-12 .

Kahuna · 12-07-2011, 03:27 PM

I don't know about your area, Ken, but if you could have a shop sonic test it, and tell you the wall thicknesses, you'd have a pretty good idea of how far you can go. I was always told to have at least .100" wall thickness and would be OK.
Jim

v8nut · 12-07-2011, 08:34 PM

You are just asking for overheating problems when boring out cylinders to the max. Much more heat goes into the water with thin cylinder walls.

Jim

V12Bill · 12-07-2011, 08:45 PM

The 1942 and early 46 blocks had a 2 15/16 bore and had the cylinder walls just as thick as the 2 7/8 bores. However a 1/8 oversize on the larger bore block is still courting problems. You could do a sonic test, but may still run into a thin spot. What do you think ,Dee?

frenchy dehoux · 12-07-2011, 11:50 PM

If you have a 1946 to 1948 block I would not go any bigger than 0.60 over. I just finished one of them you can view it on you tube.

Frenchy

Ford Flathead · 12-08-2011, 10:19 AM

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On v12's you should not go over .060. Plus there is no gaskets that will work with a bigger bore. The walls are generally thin and you do not want to junk that block.

Ol' Ron · 12-08-2011, 02:33 PM

Don't forget to send the cam to Cam techniques and have an L-100 profile put on it. Man I wonder what that would sound like??

Dee · 12-08-2011, 04:01 PM

Bored a '42 V12 block to 3-1/16" and no heating problems in fact had to install thermostats in order to get it to run 1/2 gauge ( ~170 deg's). The Water pumps are Skip's upgrades so that probably helped. Head gaskets are close and they come right up to the edge of the cylinder so you do need to be selective. You may have to have someone like Olsen's Gaskets make up a set. Running a 77B grind and adjustable tappets. This cam doesn't do alot for a flathead Ford but it really brings this V12 to life. still idles ok with a noticeable lope and gives great throttle response with the autolite 4100 carb. Had to keep this fairly "mild" as it's installed in a '48 club coupe that's intended to be a driver.

12-07-2011, 02:33 PM	#1
Ken/Alabama Senior Member Join Date: May 2010 Location: Alabama Posts: 3,261	Boring a V-12 block Anyone know how far you can bore the later V-12 blocks ? I have a 46-48 V-12 with 2 7/8" bore and want to bore it to 3 1/16 and use Ford pistons. That would be .187 overbore. I have a couple of V-8s that big but not sure about the V-12 .

12-07-2011, 03:27 PM	#2
Kahuna Senior Member Join Date: May 2010 Location: NorCal Posts: 2,617	Re: Boring a V-12 block I don't know about your area, Ken, but if you could have a shop sonic test it, and tell you the wall thicknesses, you'd have a pretty good idea of how far you can go. I was always told to have at least .100" wall thickness and would be OK. Jim

12-07-2011, 08:34 PM	#3
v8nut Senior Member Join Date: Dec 2010 Location: San Jose, CA Posts: 202	Re: Boring a V-12 block You are just asking for overheating problems when boring out cylinders to the max. Much more heat goes into the water with thin cylinder walls. Jim

12-07-2011, 08:45 PM	#4
V12Bill Senior Member Join Date: May 2010 Location: Mt. Holly,NJ Posts: 1,822	Re: Boring a V-12 block The 1942 and early 46 blocks had a 2 15/16 bore and had the cylinder walls just as thick as the 2 7/8 bores. However a 1/8 oversize on the larger bore block is still courting problems. You could do a sonic test, but may still run into a thin spot. What do you think ,Dee?

12-07-2011, 11:50 PM	#5
frenchy dehoux Senior Member Join Date: Jul 2010 Location: Queen Creek AZ Posts: 519	Re: Boring a V-12 block If you have a 1946 to 1948 block I would not go any bigger than 0.60 over. I just finished one of them you can view it on you tube. Frenchy

12-08-2011, 10:19 AM	#6
Ford Flathead Member Join Date: Jul 2011 Location: La Crescenta, CA Posts: 92	Re: Boring a V-12 block Sponsored Links (Register now to hide all advertisements) On v12's you should not go over .060. Plus there is no gaskets that will work with a bigger bore. The walls are generally thin and you do not want to junk that block.

12-08-2011, 02:33 PM	#7
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,862	Re: Boring a V-12 block Don't forget to send the cam to Cam techniques and have an L-100 profile put on it. Man I wonder what that would sound like??

12-08-2011, 04:01 PM	#8
Dee Member Join Date: May 2010 Location: Port Orchard, WA Posts: 67	Re: Boring a V-12 block Bored a '42 V12 block to 3-1/16" and no heating problems in fact had to install thermostats in order to get it to run 1/2 gauge ( ~170 deg's). The Water pumps are Skip's upgrades so that probably helped. Head gaskets are close and they come right up to the edge of the cylinder so you do need to be selective. You may have to have someone like Olsen's Gaskets make up a set. Running a 77B grind and adjustable tappets. This cam doesn't do alot for a flathead Ford but it really brings this V12 to life. still idles ok with a noticeable lope and gives great throttle response with the autolite 4100 carb. Had to keep this fairly "mild" as it's installed in a '48 club coupe that's intended to be a driver.