High Performance Big Block Cadillacs
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Author Topic: 500 Cadillac in a '54 GMC 1-ton  (Read 28197 times)
OldSub
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« Reply #30 on: November 30, 2009, 04:03:17 PM »

I like the idea of running a big gasoline powered V-8 in my tow rig, but resist the idea of spending a lot of dollars (racing valves and such) to make the motor live in this application.  I know for very modest dollars I can go Diesel instead since Cummins 6BT's can be found cheap.

Am I wrong to think the Cadillac 500 can function in a truck application as well as say a Chevy 454?  Maybe my expectations are out of whack.

I expect the motor to be turning less than 3000 rpm most the time.  Yes under acceleration it will turn more than that, but I doubt I'll ever turn it past 4500.

Based on my planned rear axle ratio (3.42) and tires (265/75-16) 70 mph is 2600 rpm.  75 is 2800.  80 is 3000.  Aside from getting a load into motion, which is a short term task, I expect the motor to work hardest sustaining highway speed with a load going up a hill.  I've crossed Marathon Pass in Colorado and it might have taken two hours of climbing (I really don't remember) to reach the summit.  I've done that with a 454 powered 1-ton pulling a trailer.

I've said my goal is to be able to cross Wyoming on I-80 at the speed limit (75) and be able to pass any time I want. 

That statement originates with experience I've had driving across Wyoming in the 454 powered 1-ton, same tire size, with 4.11 gears.  That truck had 20 inches more wheel base, four-wheel-drive and weighed probably 1000 pounds more than what I expect this truck to weigh when finished.  Its performance was adequate but not exciting. 

I'm loosing 1000 pounds and picking up 46 cubic inches while also changing rear end ratio significantly.  I was turning the 454 nearly 3400 rpm at 75 and it was not real responsive when asked to go faster.

Bigger motor with more torque, turning a little slower, I'm expecting to at least match if not beat the 454 for performance.  Today marks two years since that 454 powered truck was totaled, and I'm at least a year from finishing the '54, so by time I try it my memory may be gone...

Are the valves in the Caddy heads so weak that I'm dreaming to think I can use this motor this way?

Its not too late for me to switch my thinking to a Cummins 6BT though I'd really rather go the Caddy route.
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ST Dog
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« Reply #31 on: December 03, 2009, 11:04:08 PM »

Am I wrong to think the Cadillac 500 can function in a truck application as well as say a Chevy 454?  Maybe my expectations are out of whack.

No problem with the Cadillac in that setup.

You should not see high exhaust temperatures. You asked for a limit, and you got one. 1300o with stock valves.

Maybe a call/email to MTS or CPP and ask their opinion?

For the life of me I don't remember what CPPs dyno was set to warn at, not that they were using stock valves.
Watch the runs here, and maybe you can tell what it was (the horizontal bars lower/center of the screen)
http://www.youtube.com/watch?v=sYHQXRHiof4
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OldSub
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« Reply #32 on: December 03, 2009, 11:34:53 PM »

For the life of me I don't remember what CPPs dyno was set to warn at, not that they were using stock valves.

I could never quite read the numbers, but since it was clear the number of digits changed after the first three I'm thinking the scale was 250-500-750-1000-1250-1500 and so forth.

It looked like their line was about 1500, maybe a little lower.

I did observe that the exhaust temp never went high until that motor was turning much faster than I expect to ever turn mine. 

I think if I honor a 4,500 rpm red line I won't have any trouble keeping it cool enough to live.

Thanks for that link!  Watching that was helpful!
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dave brode
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Best of 11.66, 113.96, 1.59 sixty


« Reply #33 on: December 04, 2009, 03:23:45 PM »

Normal EGT gauges react fairly slowly.

The valve in the caddy are not "weak", and may well be better quality compared to other car engines' valves from the 70s. My concern about "car" valves may be over-paranoia. I do know that most truck engines have valves that are not the same as valves from a similar, but built for a car engine. 454 for instance. $10 says that the 1 ton and larger truck engines used a better valve.

Many a normal car has towed a heavy load. Mom, Dad, the kids and a full load on vacation gear with the A/C on, with the big camping trailer in tow.

I'm not saying that I would not tow with a good running all stock engine.  I AM saying that if I did the heads on a tow engine, I would spend the money and put a very high grade exh valve in it.

Dave
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3960 lb '71 C-10. 11.7-1 CR 514". PEP I beam rods floating MTS 18cc dish Probes, Elgin solid cam, home ported heads, MTS 2.19/1.84", Potter/Probe shaft rockers, edel 2115, 4781 850. Switch-pitch TH400, 12" 1800/3200 Tri-Shield convertor, 4.30 gears. Best so far of 11.66, 114.8 mph and 1.59 sixty
OldSub
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« Reply #34 on: December 04, 2009, 04:05:32 PM »

I do know that most truck engines have valves that are not the same as valves from a similar, but built for a car engine. 454 for instance. $10 says that the 1 ton and larger truck engines used a better valve.

You are probably right. 

It is also my understanding that small block equipped bigger trucks have lower compression because of the expectation they will see more sustained extreme usage.  That is consistent with your recommendation to stay at stock compression rather then increasing it.

I tried to confirm the better valves using an '89 K3500 as the 1-ton, because I used to have one.  I could not find a lighter '89 Chevrolet with a 454 to compare against.  The exhaust valves were $18.70 each from Rock Auto which may or may not be expensive but feel that way to me.

Actually I talk about that truck as if its gone.  It was totaled two years ago and I've been parting it out.  Much of it is still setting on the far side of my shop.

I'm not saying that I would not tow with a good running all stock engine.  I AM saying that if I did the heads on a tow engine, I would spend the money and put a very high grade exh valve in it.

I agree.  I'm just not eager to tear down a motor that runs and spend a bunch of money when I don't know how well I'm going to like the finished truck yet.

Once it's done if it proves out, I may well rebuild the second motor and upgrade many things.

I appreciate your input on this project!
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ST Dog
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« Reply #35 on: December 04, 2009, 09:55:04 PM »

Many a normal car has towed a heavy load. Mom, Dad, the kids and a full load on vacation gear with the A/C on, with the big camping trailer in tow.

Many a 50s, 60s, and 70s Cadillac has towed a big Air Stream (or similar) camper cross country.
The designers of Cadillac engines starting with the OHV engines certainly considered it in the design.









Some good discussion and pictures in this (long) thread
http://www.airforums.com/forums/f238/vintage-tow-vehicles-16089.html
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~JM~
Shop Keeper
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« Reply #36 on: December 05, 2009, 11:48:27 AM »

I recall seeing several variations of Cadillac & horse trailer combo's cruising across the SW desert in my youth. Some even had a set of Long Horns attached to the hood in Boss Hoss style. Cheesy Cool
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PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
ST Dog
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« Reply #37 on: December 05, 2009, 12:15:33 PM »

Can you imagine trying something like that, or an Air Stream, with a modern sedan?

What's the towing capacity of a Lexus or Mercedes?

Hell, what about a STS or DTS?
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OldSub
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« Reply #38 on: December 05, 2009, 12:28:26 PM »

Some good discussion and pictures in this (long) thread
http://www.airforums.com/forums/f238/vintage-tow-vehicles-16089.html

Long is right!  33 pages.  I've made it through the first 12 and saw lots of older cars and trucks pictured pulling trailers.  After my butt recovers from sitting so long I'll look at some more pages.

That group does not seem oriented toward explaining details of modifications, which is my real interest.

Thanks for the link!
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OldSub
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« Reply #39 on: December 05, 2009, 12:52:55 PM »

Can you imagine trying something like that, or an Air Stream, with a modern sedan?

What's the towing capacity of a Lexus or Mercedes?

Hell, what about a STS or DTS?

Ask google...

I found a page that shows an STS or DTS with 1,000 pound towing capacity.  Mercedes models mostly don't list a towing capacity, or they list a much higher one.  I'm not real familiar with the model numbers but suspect the ones that tow are SUV's or very big cars.  Lexus looked similar.

http://auto.howstuffworks.com/auto-parts/towing/towing-capacity/vehicle/towing-capacity-chart5.htm
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SRB
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« Reply #40 on: December 06, 2009, 07:30:01 AM »

Hello to all.

      I appreciate the knowledge and experience this forum has contributed to my Cad/Chevy project. I've been gleaning engines (3 1975 500's, 1 1971 472, 1 1968 472 and of those 2 run well) and parts for a 2000 Chevy 3500HD/6.5 turbo./auto that is shot. Intending to haul/tow as well I was thinking about using a low comp 500/4l80e with a manual valve body for three reasons.  Final ratio effect. I can buy the 4l80e's in good condition for $300. I'm thinking unloaded the upshift process would not take to long and relatively painless. 
     Right now the truck gets ten MPG loaded, or 10.5 MPG unloaded downhill with the wind,  diesel is not getting cheaper, turbos are expensive, yada, yada, yada.
     Any advice on pitfalls is greatly accepted.

Regards

Steve
       
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OldSub
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« Reply #41 on: December 06, 2009, 11:15:58 AM »

Any advice on pitfalls is greatly accepted.
Look for posts by rickpilgrim.  He has put Cadillac's in some later trucks including converting a Diesel and he seems to have some good ideas on how to make it work.

I've seen 4L80e transmissions on craigslist as low as the $300 neighborhood, but you also need a computer to run that transmission.  What are your plans regarding that?

What are the rear gears in this 3500HD and what size tires are you planning to run?
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SRB
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Yep, its a oil road.


« Reply #42 on: December 06, 2009, 05:50:36 PM »

Hello Oldsub
     From what Transgo says I can run a totally manual vb Kit on the 4l80e ( $125 ) if I don't mind shifting and forget the controller.  If I understood their adds correctly I can take off in any gear and full throttle any shift.  Hah!   Tires are 225/75/19.5, rear axle is 4.63, definatelly not ideal even with the .75 od ratio of the 4L80E but I have to start somewhere.
     The 6.5 has never (owned it for years) been impressive on performance or mileage compared to my Ford 1 ton 7.3 turbo. It gets 12MPG and will pull the Chevy sideways, starts good cold, on and on.  Don't get me wrong, I don't like much about Ford BUT the powerstroke has earned it's due.   
     Anyway... I don't think I want to spend $$$$ for a duramax, so I'm looking at options. 
 
     What is your game plan?

Regards

Steve   
     
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OldSub
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« Reply #43 on: December 06, 2009, 06:41:39 PM »

What is your game plan?

This thread is really about my project and reading the first page gives most the information.

Today the frame is setting in my shop with the 14-bolt (10.5 FF) with 3.42 gears already installed.  The IFS conversion using '72 Chevy C20 stuff is almost complete, lacks drilling a few holes, and a little welding and grinding on the adapter brackets.

The power steering will be completed along with the IFS install.  I need to fab up one more steering box mount and haven't mounted the idler arm yet.

With the IFS and steering done I want to mock up the engine and transmission mounting and refit the cab and fenders to be sure everything is going to fit as I need it to.

It appears to me that I will have a problem around the exhaust outlets.  I'm leaning toward mounting the motor an inch or maybe two inches higher and lifting the cab.  While this is a 2-wheel-drive truck I would like it to stand proud, and lifting the cab and front fenders will also improve tire clearance, which is one of the challenges created by using the IFS I've chosen.

I'd like to stay with cast manifolds rather than headers to reduce noise.

With the cab and fenders in place I plan to push the truck outside and work on the motor and perhaps deal with some other projects.  I have a 472 block and an extra TH400 that will probably be in the truck as mock up instead of either of the 500s I have.  That's how I can mock it up and work on the motor at the same time.

Current thinking is I'll use my running '76 500, and I'll replace the timing chain and sprockets and valve seals.  Replace the intake with the Edelbrock 2115 and the cam with the MTS #5 or maybe the #3.  Since this motor came from a Deville I'll be changing the pan and pickup and thinking hard about replacing the oil pump.

Other issues....

I plan to use the tilt-tele column from a '76 Deville in the truck mostly because I have one.  I have a set of worn Honda Accord leather bucket seats that I like and will probably use in this truck.  My plan is to adapt a swing pedal and firewall mount brake booster/master though I've not done anything toward choosing one or mounting.

I have both a '54 GMC cab and a '55 1st.  I have changed my mind several times regarding which one will end up on this frame.  The '55 1st needs more rust repair but I keep thinking of another project where I'd like to use the '54.  I still haven't got the paperwork sorted out on the '55 1st and to use it I really need to get that done.

I've said I'm going to mount a utility box on the back of this truck, but have several other ideas and no immediate need to make my mind up.  One idea is to use the body from a 1-ton panel to create a rounded bed.

I haven't found the right wheels yet.  I've seen pictures of what I think I need, from a Dodge 3/4-ton pickup, but haven't found any yet.  I have three nearly new Michelin 265/75-16s ready to mount once I have the wheels and will need a fourth tire at some point.

Meanwhile the transmission is failing in my K2500 so I'm going to need to repair it or finish this project or get another truck to tow my trailer.  My preference is to finish this project though I know I'll have to fix the K2500 even to sell it.

So you may have more info here than you really wanted...

This is all moving in slow motion because I'm also dealing with some health issues and what might sound like a weekend's work is likely to make me months at my current pace.
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Fishwacker
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« Reply #44 on: December 06, 2009, 10:15:49 PM »

I've heard that the filter relocation kits have failed allowing the motor to loose oil pressure.  I'm trying to think of a source for that information and not coming up with anything at the moment.  Maybe I'm worried about a non-issue?

I've also seen some posts here and elsewhere regarding oil pumps, maybe I'm confusing the two.

 If you install one of Summit's Oil Pressure Safety Switches per the instructions, it'll shut the engine down to prevent damage.  http://www.summitracing.com/parts/SUM-G1438/ Might be a good investment @ $16.95.
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