| New Engine build [message #315172] |
Tue, 28 March 2017 19:22  |
dr.diesel
Messages: 85
Registered: April 2015
Location: The Haute, Indiana
Karma: 0
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I've read just about every engine build thread available here, but nothing matches what I've got in mind!
Goal:
- 2-3 week vacation duration (so a bit more gear weight)
- Towing enclosed trailer with 5000lb vehicle
- Ability to *better* maintain grades
- Willing to sacrifice fuel economy for performance, value is not a primary build consideration
- Mostly likely 3.70 final drive ratio
Considering the following:
- 4.5" Stroker 455
- C Heads (I realize at the factory 3.07 final drive Cs make no sense, but at 3.70s and 3000RPM cruise (~490ci engine) these may hold a benefit perhaps??)
- 8.5:1 True compression ratio (fully polished combustion chambers, 180F thermo)
- Roller cam
I wasn't able to find conclusive documentation on the J vs C heads in terms of intake CCs, J heads approx 190CCs and ~240 for the Cs as my guess? The Js make perfect sense at a 2400RPM cruise but the Cs might begin to shine nudging +3000RPMs. Hardened exhaust seats would of-course be installed if I went Cs.
I've already got the AL intake and Doug Headers on my current, but tired 455. This build has yet to begin, so nothing is concrete and all options are open. My local machine shop has an engine Dyno, so whatever combo I end up will WILL be dynoed.
All thoughts welcome and appreciated, thanks.
77 Kingsley
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| Re: New Engine build [message #315173 is a reply to message #315172] |
Tue, 28 March 2017 20:31  |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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I'm not an Olds engine builder, but be sure that the stroker idea makes mechanical sense before going that route, meaning increased side loads on piston and rods and exposed piston skirts. If I were diong an engine today the first thing I would look at is higher comp 9 to 9.5 to 1. Traveling through the Rockies last fall it seemed higher compression would help with enemic power at altitude. Seems you could retard timing a few at sea level and at altitude detonation is not an issue anyway. Rather than longer stroke it could be made up more economicly with compression and a few more RPM. The ultra low compression of the late 70s seems to be creeping up each year on new cars and granted electronic controls, but EFI with spark control could be added and beneficial.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: New Engine build [message #315180 is a reply to message #315172] |
Tue, 28 March 2017 21:12 |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
Karma: 5
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Maybe C heads will work if you install exhaust valve seat inserts.
I used G heads on mine. They were the first year with hardened valve seats for unleaded fuel.
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: [GMCnet] New Engine build [message #315186 is a reply to message #315172] |
Tue, 28 March 2017 22:19 |
Kosier
Messages: 834
Registered: February 2008
Karma: 1
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Senior Member |
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The true and correct answer is 500 inches of Cadillac.
Gary Kosier
77PB w/500Cad
Newark, Ohio
--------------------------------------------------
From: "Andy"
Sent: Tuesday, March 28, 2017 8:22 PM
To:
Subject: [GMCnet] New Engine build
> I've read just about every engine build thread available here, but nothing
> matches what I've got in mind!
>
> Goal:
>
> - 2-3 week vacation duration (so a bit more gear weight)
> - Towing enclosed trailer with 5000lb vehicle
> - Ability to *better* maintain grades
> - Willing to sacrifice fuel economy for performance, value is not a
> primary build consideration
> - Mostly likely 3.70 final drive ratio
>
> Considering the following:
>
> - 4.5" Stroker 455
> - C Heads (I realize at the factory 3.07 final drive Cs make no sense, but
> at 3.70s and 3000RPM cruise (~490ci engine) these may hold a benefit
> perhaps??)
> - 8.5:1 True compression ratio (fully polished combustion chambers, 180F
> thermo)
> - Roller cam
>
> I wasn't able to find conclusive documentation on the J vs C heads in
> terms of intake CCs, J heads approx 190CCs and ~240 for the Cs as my
> guess? The
> Js make perfect sense at a 2400RPM cruise but the Cs might begin to shine
> nudging +3000RPMs. Hardened exhaust seats would of-course be installed if
> I
> went Cs.
>
> I've already got the AL intake and Doug Headers on my current, but tired
> 455. This build has yet to begin, so nothing is concrete and all options
> are
> open. My local machine shop has an engine Dyno, so whatever combo I end
> up will WILL be dynoed.
>
> All thoughts welcome and appreciated, thanks.
>
>
>
> --
> 77 Kingsley
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: [GMCnet] New Engine build [message #315188 is a reply to message #315186] |
Tue, 28 March 2017 23:59 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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You are asking a lot for an aspirated gas engine with a 3 speed transmission . Towing a 5,000 lb car in a 3,000 + pound trailer would be a heavy load for a turbo charged diesel with a 6 speed Alison in the western mountains. I wouldn't consider it but I wouldn't have a big problem with it flat land towing if you have really good brakes on the trailer . Don't do it if you plan on climbing any steep grades believe me you will hate it.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] New Engine build [message #315191 is a reply to message #315188] |
Wed, 29 March 2017 07:39 |
Dolph Santorine
Messages: 1236
Registered: April 2011
Location: Wheeling, WV
Karma: -41
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Senior Member |
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Besides, an enclosed car trailer with a steel frame is more like 5,000 pounds.
But the real issue it taking a look at the rear frame on the coach. I don’t believe it’s up to it, no matter how you reinforce it.
But that’s my .02. Your mileage may vary.
Dolph Santorine
Wheeling, WV
26 foot Palm Beach
> On Mar 29, 2017, at 12:59 AM, roy keen wrote:
>
> You are asking a lot for an aspirated gas engine with a 3 speed transmission . Towing a 5,000 lb car in a 3,000 + pound trailer would be a heavy load
> for a turbo charged diesel with a 6 speed Alison in the western mountains. I wouldn't consider it but I wouldn't have a big problem with it flat land
> towing if you have really good brakes on the trailer . Don't do it if you plan on climbing any steep grades believe me you will hate it.
> --
> Roy Keen
> Minden,NV
> 76 X Glenbrook
>
> _______________________________________________
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| Re: New Engine build [message #315196 is a reply to message #315172] |
Wed, 29 March 2017 08:48 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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All engines have their inherent weakest links. Caddy have the rockers and thrust bearing oddities. Can be addressed and solved. For Olds I would say rod bearing big end issues from experience. For that reason I questioned the wisdom of stroker in comment above. Anything that further taxes that part of the engine seems a bad idea. I would rule out a steel frame trailer right away. All aluminum is only way to go for this situation. Neo makes some really nice ones with aluminum wheels as well.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] New Engine build [message #315197 is a reply to message #315196] |
Wed, 29 March 2017 09:25 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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The Olds 455 is already a "stroker" configuration. Lengthening the stroke
will not do much for its longevity. But, you said you only wanted to make
one run out west and back, so I interpret that as meaning you are
relatively unconcerned about longevity. But, length of stroke is not the
only way to increase torque. Intake runner design and size, valve
diameters, compression ratio, chamber design, exhaust port size and shape,
manifold design, vs headers, exhaust system, camshaft selection and timing
all play a much larger role in torque production than stroke length. Stay
under 5000 sfpm piston speed if you don't want it to self destruct. Diesel
conversion becomes economic reality when spending the kind of money you
will need to make the level of torque you will need to flatten the hills
with the loads you propose. You might look at 4:10 to 1 final drive, too.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Mar 29, 2017 6:49 AM, "John R. Lebetski" wrote:
> All engines have their inherent weakest links. Caddy have the rockers and
> thrust bearing oddities. Can be addressed and solved. For Olds I would say
> rod bearing big end issues from experience. For that reason I questioned
> the wisdom of stroker in comment above. Anything that further taxes that
> part
> of the engine seems a bad idea. I would rule out a steel frame trailer
> right away. All aluminum is only way to go for this situation. Neo makes
> some
> really nice ones with aluminum wheels as well.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: New Engine build [message #315206 is a reply to message #315172] |
Wed, 29 March 2017 15:32 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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OK, you're gonna haul 8000 pounds behind an 11000 pound GMC with a stroker 455 which is already undersauqre and turn it up with a 3.7 gear set? You're probably going to break things. I believe I'll stand back and watch. Just for the hell of it, ask Manny Travao what warranty he'll offer for one of his beefed up rebuilds in that service.
Good luck,
Johnny
n.b. Local guy is looking to sell a GM 4106 conversion with an 8v71 in it. It would haul that load without a lot of problem, though you'd need to come down a gear or two over the hills.
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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