The Stovebolt Site Forums The Parking Lot Big Bolts 454 Quadrajet, 454 TBI or Cadillac 500 Quadrajet

I've asked a couple other questions as I'm planning my '54 GMC 1-ton. Current plan is a GM 14-bolt rear with 3.42 gears. Transmission will be a TH400 if I go Cadillac, and either a TH400 or a TH475 if I go 454.

I plan to use this truck to pull my 18 foot flatbed trailer with loads as big as a 2-ton truck. I don't plan to run it very far but would not rule out a multi-thousand mile trip sometime in the future.

Most trips will be within 200 miles of home and while I am not likely to run faster than the speedlimit, I don't like to loaf, so maintaining highway speeds is important. And I want plenty of grunt for pulling loads uphill. I've already decided I can handle 10 mpg for a limited use vehicle even at $5 or $6 a gallon.

I have the three motors I mention as options. The 454 Quadrajet and the 454 TBI are both still in vehicles and with a battery they both start and run without smoking. Neither is low milleage, but both should have lots of life left. The TBI motor I've driven thousands of miles, the Quadrajet motor I've only driven a few miles, but know its history back about 15 years. Both 454s are truck motors, one in a 1-ton the other a motorhome.

The Cadillac I know less about. Knowing when Cadillac made the 500 I know its older than the other two, but know nothing else about its history. I've never seen it run and currently it sets on my floor in my shop. It was sold me as a runner, but I don't know that with certainty.

Which would you choose? I'm feeling inclined toward the Cadillac, but could be persuaded to use one of the others. What do you think? What would you want to know before deciding?

I hope to be mounting the motor in the coming months, so I really need to decide which motor... One of the motors not used in this project will be used in my COE project. I'm sure I'll use the third on something also.

I am guessing Cadillac, but being as you don't have a diesel choice I don't have much of an opinion.

Have you done a compression check on the 500, that may decide for you one way or the other really quick..
It may be worth puling the heads to peak at the cylinders and possibly a valve job?

Do both engine choices fit the same, is one physically smaller or shaped better to fit your truck than the other?

Grigg

I would use a stand alone computer and run the 454 TBI just for the ease of driveability. It will start right up, fast idle, idle down after warm up and not vapor lock when pushed hard. There's also the availablity and economics of parts that are available most everywhere for the 454's over the Caddy engine.

There's my opinion, but I may be a bit biased. I'm putting an '89 TBI 454 in my 54 COE one of these days, LOL,
Scott

Well Grigg you know me and Diesels, I'd rather hear a gas powered V-8 growling than the Diesel. It may have something to do with the Diesel milk truck that wakes me several times a week but more likely its just the old hot rodder in me coming out.

I've not checked compression on any of the three and probably should. I've been toying with putting the Cadillac in some kind of test stand to run it before mounting it in the truck. I'd like to think once choosing one of the three I'd be willing to spend enough to freshen that motor if required.

Scott my TBI 454 is in an '89 too. But its not original to that truck its a replacement so I don't know what year you would say it really is. I'm still new to computer controlled motors and that aspect alone argues against that motor for me.

The Cadillac weights less and makes more torque. Those are factors that make it appeal to me. Also its not a Chevy so its not a belly button motor. The dimensions are similar and since I have to move the steering box either way the other measurements don't make a lot of difference.

I can buy an engine mount for the Chevy but will have no choice but to make one for the Cadillac.

Most the easily replaced parts for the 30 year old Cadillac are not hard to find. It would be much harder to rebuild along the side of the road, but ignition and carb parts aren't hard. It might take a day to get a water pump or starter.

Thanks for the responses guys!

Any comments on the torque versus weight comparisons on these motors for my application?

The 429/472/500 Cadillac engines are real sleepers. They only weigh slightly more than a small block V-8 and they make gobs of torque. My family put over 300,000 miles on a 472 in a Fleetwood Brougham, including a trip from Tennessee to California and back, towing a big trailer. On the return trip, the gross weight of the car/trailer combo was 16,700 lbs. The 3-axle trailer had a little over 10,000 lbs. on it. I got 5 MPG for over 2,500 miles, but the old Caddy never missed a beat. Here's the kicker- - - -it rolled over on 200,000 miles on the outbound trip! When I retired the car for major front end wear, the car was well over 300K and neither the engine nor the transmission had any major repair- - -just tuneups, fluid and filter changes, etc. It did twist the center out of the flex plate- - - - -twice!

Keep the engine and transmission well-lubricated and cool, and that Caddy will do anything you ask of it!
Jerry

I'm starting work on a 47 Fletwood Caddy that has the 472 in it,from 1972 and matching trans, and I'm not too impressed, there has been some carb work done and a couple other things, but knowing what goes on I'll end up rechecking everything, timing may be off a little and the plugs need to be changed, this may require removing fenders or the inners.

Okay you guys have helped me decide to at least further evaluate the Cadillac.

I particulary appreciate the story of a Fleetwood Brougham (weighing at least what my truck does) pulling a 10,000 pound trailer cross country. It confirms I'm not nuts to consider that motor for this application.

I'll get the motor on the engine stand and pull the pan and check compression and maybe even pull the heads to peak inside. Unless I find something really wrong (guaged by my comfort spending money the day I make the choice) it looks like the Cadillac will be the new power plant.

And Scott, I've read of a few guys using the TBI setup off a 454 to convert one of these big Cadillacs to EFI. If I get brave I may even try that...