New Engine build

[andy]

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

 

[john r. lebetski]

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

 

[bill wevers]

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

 

[bd5av8r]

Cummins diesel conversion. Yes it's been done in a GMC, and it would meet
your requirements. Add a diesel generator for a complete system.
Sammy Williams

 

[kosier]

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

 

[roy keen]

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

 

[adolph santorine]

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

>
> 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
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[john r. lebetski]

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

 

[Jim Hupy]

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

> 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
>

 

[andy]

Thanks to all for the thoughts.

Staying under 5000fpm means under 6600RPM, that shouldn't be an issue, he he. I'll further ask around on the Olds forums, but there are lots of guys
running 4.5" strokers, abit in a much different use scenario. I drive about 2k miles a year in the GMC, this might expand to 3k when the boys are out
on their own, if I can get 50K miles out of this engine I'd be happy. By then I'll just install the Walmart knock-off branded Mr. Fusion. :d

--
77 Kingsley

 

[johnny]

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.

--
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" - ol Andy, paraphrased