The Ford Barn

trvguy · 03-28-2014, 07:48 PM

can any one tell me if any flatheads were factory relieved? what years?
thanks
trvguy

scooder · 03-28-2014, 08:42 PM

Yep, they certainly did. It ain't a fancy hotrod style shaped relief. Just a kind of milled straight sided slot.
When they started or finished I don't know for certain, but got a 99A here (1939 Merc type) with factory relief.
I have been led to believe that the relief was done because the stock area tween the valves and bore forms a sharp ridge, and this sharp part acted as a stress point, and when used on the big trucks with air brakes, the mixture leans out when theses braked are applied, and this lean out would cause that Sharp part to go silly hot, and then crack. This is what I was told, and it sorter makes sence. I say sorter cause I'm not fully versed on these old air brakes and how they worked.
Martin.
Just re-read this and didn't clearly say, the relief removed that Sharp part (stress riser if you will) and helped to combat the crack. So I wad told.

Neal · 03-28-2014, 09:38 PM

I have the same answer as scooder. I have one and it was in a truck, am guessing around 39 or 40. It had a 3 3/16 inch bore.

Neal

Graeme / New Zealand · 03-28-2014, 09:41 PM

I've got a 99A block that is also relieved.

GB

59ab · 03-28-2014, 09:42 PM

I have a 59A engine (1945) 239 cid factory relieved.

Walt Dupont--Me. · 03-29-2014, 07:12 AM

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I've rebuilt quite a few 59 blocks factory reliefed. They all came out of big truck engines. I understood the factory did this to the big truck engines to keep them from pinging with a big load on. Some street rodders think they have something with this block but to me there just loosing compression. I'm sure they work good with high RPM engines and with a super charger. Walt

scooder · 03-29-2014, 10:45 AM

Walt, good call on the ping, spose the sharp bit that's removed with this relief could also with its stupid hot possibility could also onset ping and or detonation.
Martin.

rg130 · 03-29-2014, 10:56 AM

I have a factory relieved 59 block 239 with a raised area for the intake manifold. I'm not sure what year it was produced. Were 59 blocks with raised intakes produced prior to 1946? If so, were they only for trucks? Thanks for any input.

flatheadfan · 03-29-2014, 11:33 AM

I have a 59L that I believe was a late War issue and it has a relief.

Tom

03-28-2014, 07:48 PM	#1
trvguy Member Join Date: May 2010 Location: upper peninsula of michigan Posts: 80	factory relieved blocks can any one tell me if any flatheads were factory relieved? what years? thanks trvguy

03-28-2014, 08:42 PM	#2
scooder Senior Member Join Date: Jul 2010 Posts: 2,593	Re: factory relieved blocks Yep, they certainly did. It ain't a fancy hotrod style shaped relief. Just a kind of milled straight sided slot. When they started or finished I don't know for certain, but got a 99A here (1939 Merc type) with factory relief. I have been led to believe that the relief was done because the stock area tween the valves and bore forms a sharp ridge, and this sharp part acted as a stress point, and when used on the big trucks with air brakes, the mixture leans out when theses braked are applied, and this lean out would cause that Sharp part to go silly hot, and then crack. This is what I was told, and it sorter makes sence. I say sorter cause I'm not fully versed on these old air brakes and how they worked. Martin. Just re-read this and didn't clearly say, the relief removed that Sharp part (stress riser if you will) and helped to combat the crack. So I wad told. Last edited by scooder; 03-28-2014 at 09:15 PM.

03-28-2014, 09:38 PM	#3
Neal Senior Member Join Date: May 2010 Location: North Dakota Posts: 129	Re: factory relieved blocks I have the same answer as scooder. I have one and it was in a truck, am guessing around 39 or 40. It had a 3 3/16 inch bore. Neal

03-28-2014, 09:41 PM	#4
Graeme / New Zealand Senior Member Join Date: May 2010 Location: Lower Hutt , New Zealand Posts: 2,126	Re: factory relieved blocks I've got a 99A block that is also relieved. GB __________________ "you can't make honey out of dog sh*t" "You're a long time looking at the lid"

03-28-2014, 09:42 PM	#5
59ab Senior Member Join Date: May 2010 Location: Huntsville,Alabama Posts: 247	Re: factory relieved blocks I have a 59A engine (1945) 239 cid factory relieved.

03-29-2014, 07:12 AM	#6
Walt Dupont--Me. Senior Member Join Date: May 2010 Location: Gardiner Me. Posts: 4,200	Re: factory relieved blocks Sponsored Links (Register now to hide all advertisements) I've rebuilt quite a few 59 blocks factory reliefed. They all came out of big truck engines. I understood the factory did this to the big truck engines to keep them from pinging with a big load on. Some street rodders think they have something with this block but to me there just loosing compression. I'm sure they work good with high RPM engines and with a super charger. Walt

03-29-2014, 10:45 AM	#7
scooder Senior Member Join Date: Jul 2010 Posts: 2,593	Re: factory relieved blocks Walt, good call on the ping, spose the sharp bit that's removed with this relief could also with its stupid hot possibility could also onset ping and or detonation. Martin.

03-29-2014, 10:56 AM	#8
rg130 Member Join Date: May 2012 Location: Placerville, CA 95667 Posts: 96	Re: factory relieved blocks I have a factory relieved 59 block 239 with a raised area for the intake manifold. I'm not sure what year it was produced. Were 59 blocks with raised intakes produced prior to 1946? If so, were they only for trucks? Thanks for any input.

03-29-2014, 11:33 AM	#9
flatheadfan Senior Member Join Date: May 2010 Location: West Michigan Posts: 1,218	Re: factory relieved blocks I have a 59L that I believe was a late War issue and it has a relief. Tom