Overbore Size

Carl Stouffer

Carl Stouffer

Well-known member
Jan 15, 2009
4,693
381
83
Tucson, Arizona 85718
Long story, but I have a full reciprocating assembly that I acquired from Steve Ferguson, that HE got from another GMCer who received it as part of a
warranty settlement from Mondello. The only problem is that (I believe) it has .060 over pistons and rings. I am looking for opinions on whether or
not this much of an overbore is an issue on a 455. If it is even questionable, I will try to work out some kind of a deal on those parts and go with
about a .030 overbore.
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member
 
.060" is OK on the 455. .030" on the 403. If in doubt, have a sonogram
done on the block. Probably not a bad idea in any event.
Jim Hupy
Salem, Or.

> Long story, but I have a full reciprocating assembly that I acquired from
> Steve Ferguson, that HE got from another GMCer who received it as part of a
> warranty settlement from Mondello. The only problem is that (I believe)
> it has .060 over pistons and rings. I am looking for opinions on whether or
> not this much of an overbore is an issue on a 455. If it is even
> questionable, I will try to work out some kind of a deal on those parts and
> go with
> about a .030 overbore.
> --
> Carl Stouffer
> '75 ex Palm Beach
> Tucson, AZ.
> Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive,
> Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American
> Eagles,
> Solar battery charging. GMCSJ and GMCMI member
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
On a LOT of engines 0.060" is probably over the RECCOMMENDED maximum.
Ken H. knows some engine people that could probably give a very educated opinion.
0.060" might work on a particular block but not on another of the same type/brand, etc.
Core shift.
Ken H's friend might also be willing to tell us about "core shift"
--
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
 
Dave,
You are not that far from Dick Paterson up in Coldwater, ONT. You can reach him at 705 325-4554. He is the go to person on the 455 engine and the 403 too.

J.R. Wright
GMC GreatLakerTech Editor
78 Buskirk 30' Stretch
75 Avion Under Reconstruction
Michigan

>
> On a LOT of engines 0.060" is probably over the RECCOMMENDED maximum.
> Ken H. knows some engine people that could probably give a very educated opinion.
> 0.060" might work on a particular block but not on another of the same type/brand, etc.
> Core shift.
> Ken H's friend might also be willing to tell us about "core shift"
> --
> DAVE KING
> lurker, wannabe
> Toronto, Ontario, Canada
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
It's worth the time to contact people like Dick Patterson as he is familiar with the 455/403

Sent from my iPhone

>
> Dave,
> You are not that far from Dick Paterson up in Coldwater, ONT. You can reach him at 705 325-4554. He is the go to person on the 455 engine and the 403 too.
>
> J.R. Wright
> GMC GreatLakerTech Editor
> 78 Buskirk 30' Stretch
> 75 Avion Under Reconstruction
> Michigan
>

>>
>> On a LOT of engines 0.060" is probably over the RECCOMMENDED maximum.
>> Ken H. knows some engine people that could probably give a very educated opinion.
>> 0.060" might work on a particular block but not on another of the same type/brand, etc.
>> Core shift.
>> Ken H's friend might also be willing to tell us about "core shift"
>> --
>> DAVE KING
>> lurker, wannabe
>> Toronto, Ontario, Canada
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Keep in mind that .060" is only .030" on each side. Less than 1/32". The
455 is an "OLD SCHOOL" engine. SMALL bore, LOOONG stroke. Lots of meat
around the cylinders, and a really good casting with high nickel content.
Not much problem with "core shift" in these engines compared to "modern"
engines like 350 chev. Don't believe me? Ask Dick Paterson.
Jim Hupy

It's worth the time to contact people like Dick Patterson as he is familiar
with the 455/403

Sent from my iPhone

>
> Dave,
> You are not that far from Dick Paterson up in Coldwater, ONT. You can
reach him at 705 325-4554. He is the go to person on the 455 engine and
the 403 too.
>
> J.R. Wright
> GMC GreatLakerTech Editor
> 78 Buskirk 30' Stretch
> 75 Avion Under Reconstruction
> Michigan
>

>>
>> On a LOT of engines 0.060" is probably over the RECCOMMENDED maximum.
>> Ken H. knows some engine people that could probably give a very educated
opinion.
>> 0.060" might work on a particular block but not on another of the same
type/brand, etc.
>> Core shift.
>> Ken H's friend might also be willing to tell us about "core shift"
>> --
>> DAVE KING
>> lurker, wannabe
>> Toronto, Ontario, Canada
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

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.060 over is somewhat common. The only real down side is that it can't be bored again. In a motorhome. You'll never live long enough to have that as an issue. Bob Dunahugh
 
With the amount of work it takes to R and R an engine in a TZE, I would not want a + .060 in mine when pulling a long long grade over 6%.
I would put a meatier block in the MH and use that one in a Cutlass, 442, or 98 where long term heat loads are much lower.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
John, you are certainly entitled to your opinion. Spend your money however
you see fit.
Jim Hupy

With the amount of work it takes to R and R an engine in a TZE, I would not
want a + .060 in mine when pulling a long long grade over 6%.
I would put a meatier block in the MH and use that one in a Cutlass, 442,
or 98 where long term heat loads are much lower.
--
John Lebetski
Woodstock, IL
77 Eleganza II

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I have a 10k engine that runs great so hopefully I won't be spending any money on it at all!
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
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