500 caddy big block and a 6spd...!

[no_rice]

so.... last week i bought myself a t56(from a 94-95 firebird lt1) to go in my 70 gmc shortbox, and figured for awhile i would either bolt it up the the old good running 350 i have in my truck, or MAYBE do an ls swap while i swap the trans(just really not wanting to do the ls because of how common its become, even though its a great setup)

well, now i have stumbled across what appears to be a 70 cadillac 500(400 horse 550 torque)... carb to pan, fan to flywheel. ive been researching for the last 2 days what it would take to put this combo together and in my truck.

has anyone seen this combo before? it will apparently take SOME sort of BOP bell housing to get the 2 mated together from the little bit of info i can find. the crank has to be drilled for a pilot bushing or something similar. obvious crossmember and floor modifications...

ill have to figure out headers since i believe the caddy pattern is different from other big blocks?(somewhere i think i came across an adapter to fit 396/454 style headers to the caddy motor)

side question, i think i remember seeing that a big block has trouble clearing the normal power brake booster setup?(just trying to cover bases)

my biggest concern seems to be mating the t56 to the 500. our trucks were available with big blocks so mounts shouldnt be a problem, crossmembers can be moved/modified, floor and shifter can be customized. drive shaft will have to be built and i'll have to figure out the steps for setting the trans to pinion angle correctly.

and guess i should wait on dropping the front another inch if i plan on adding a wee bit more weight to the front end... lol

any useful info or leads on this would be appreciated.

[kwmech]

There have been several conversions to the caddy and oldsmobile engines over the years. Couple of threads just recently, search around and you should come up with them

[low&slow]

I put a 500 caddy in my truck with no issues at all. Turbo 400 tranny. If done right you won't need to massage anything on the firewall.

[low&slow]

Originally Posted by no_rice

so.... last week i bought myself a t56(from a 94-95 firebird lt1) to go in my 70 gmc shortbox, and figured for awhile i would either bolt it up the the old good running 350 i have in my truck, or MAYBE do an ls swap while i swap the trans(just really not wanting to do the ls because of how common its become, even though its a great setup)

well, now i have stumbled across what appears to be a 70 cadillac 500(400 horse 550 torque)... carb to pan, fan to flywheel. ive been researching for the last 2 days what it would take to put this combo together and in my truck.

has anyone seen this combo before? it will apparently take SOME sort of BOP bell housing to get the 2 mated together from the little bit of info i can find. the crank has to be drilled for a pilot bushing or something similar. obvious crossmember and floor modifications...

ill have to figure out headers since i believe the caddy pattern is different from other big blocks?(somewhere i think i came across an adapter to fit 396/454 style headers to the caddy motor)

side question, i think i remember seeing that a big block has trouble clearing the normal power brake booster setup?(just trying to cover bases)

my biggest concern seems to be mating the t56 to the 500. our trucks were available with big blocks so mounts shouldnt be a problem, crossmembers can be moved/modified, floor and shifter can be customized. drive shaft will have to be built and i'll have to figure out the steps for setting the trans to pinion angle correctly.

and guess i should wait on dropping the front another inch if i plan on adding a wee bit more weight to the front end... lol

any useful info or leads on this would be appreciated.

There are a few kits you can buy to fit big block headers on. You'll run into clearance issues though between the frame rails. A custom set will need to be made. The front crossmember required zero mods. I had to make a tranny crossmember though.

As far as weight goes, a 500 caddy weighs less than a 454. The front on my truck actually sits a tad higher than the back.

[Bigdav160]

Does someone make a flywheel for the Cadillac? I can't remember ever seeing anything but an automatic behind one.

[MARKDTN]

I am going to go against the grain and ask why? If you did an LS swap it will fit and you can use standard type parts. With a Caddy and 6-speed you need custom headers, custom bellhousing, drill the crank for pilot bushing (are you going to do it with engine together or take it apart?), custom flywheel..... For all the time and money you are going to spend you could build an LS with similar power that will get better mileage and will be easier to cool and so forth. I like something different, but fuel is expensive and it's only going up. If it is not a trailer queen, you have to consider fuel costs. If you want something different how about a 4.8 LS with twin turbos and a 6-speed. Hot Rod tried to kill one and couldn't. They put 26 lbs boost to it and were over 1200HP and could not blow it up.

http://www.norotors.com/index.php?topic=7879.0

[no_rice]

ill be honest, when i really sit down and think about it, alot of it boils down to the fact that it will be something different. so many things you open the hood on these days has an ls swapped into it. for good reason sure, but its still the same motor that the next guy has.

first, how many of these trucks do you open the hood and see a 500 caddy big block. and on the rare occasion you do, how many of those are mated to a 6 speed. not many.

plus with the torque from that motor, it should be able to pull that double over drive 6th gear really well...!

[gvw5400]

If your committed to the cost and work involved I say GO for it!
Making this into YOUR truck is hard to put a price on.
My thoughts are do an assessment on time ,cost and work involved so you
don't get bogged down in the project and have to walk away from it.
I love seeing someone going against the grain to build YOUR OWN truck.
All the best, Dirk

[davepl]

Different is good, but different is work. You have to make the call of whether the amount of work it's going to take is worth the ability to say and show a Cadillac motor in your truck. You have to do the calculus on that though. Just don't confuse an idea what feels exciting today with a project you're still going to want to be fabricating on 60% of the way in.

As for your username:

[geezer#99]

I say dare to be different!!
There's a couple sources out there for parts including flywheels and adaptors for bellhousings.
Check these out.
http://www.cad500parts.com/
http://www.500cid.com/
http://www.cadillacperformanceparts.com/

[Steeveedee]

Originally Posted by davepl

Different is good, but different is work. You have to make the call of whether the amount of work it's going to take is worth the ability to say and show a Cadillac motor in your truck. You have to do the calculus on that though. Just don't confuse an idea what feels exciting today with a project you're still going to want to be fabricating on 60% of the way in.

As for your username:

I likes my spuds, and have little use for rice, though my wife likes it, lol. ONE furrin car in the family, my long distance commuter, a Corolla. Now, the back tires on that car equal MEAT.

[1972RedNeck]

I helped stick a 472 in '70 Highboy Ford. On the first go around, my brother built his own bell housing to mate a Clark 5 speed to it. We machined our own flywheel that bolted on with the flex plate (flex plate had the ring gear to start it). We scrounged a pressure plate out of our junk pile. We found one that had 9 bolt holes and figured that it must be heavy duty. Unbeknown to us at the time, this was off of a 270 GMC which basically made the whole project go bust.

The manual all bolted up and worked good until the clutch got smoked. When trying to find a new clutch set, we figured out what we had for a pressure plate. Long story short, they use a small diameter bolt circle and are obsolete.

We could find no other pressure plate with a bolt circle small enough (he made the flywheel none too big) so instead of making a new flywheel we reverted back to the turbo 400 which was promptly smoked.

We then bought a BOPC to Chevy adapter and ran a 700R4. The adapter plate was too thin and flexed which ate flex plates. So we built our own 3/8" thick adapter plate. ll was well until the 700R4 crapped out. It was built up and then was starting to slip when we got frustrated and sold it.

IIRC, for the pilot, we took one out of an FE, turned it down to the right size and drilled the center out a smidge. The crank had a recess.

[1972RedNeck]

This place has flywheels and other goodies.

http://www.cad500parts.com/index.htm

[lowrollin70gmc]

It is fun to be different, but I would worry about 500 cubes of caddy torque going through an early T56. They're only rated to 400 ftlbs and can spit up synchros easily. Double overdrive also wouldn't be a great idea with a lot of torque, as overdrives are weaker than a direct drive and create a lot of heat. That can be overcome by not hammering it down in 0.50 6th, but something to be mindful of.

Another worry would be the clutch and flywheel. LT1 T56s use a pull type clutch/pressure plate instead of the more normal push type pressure plate. I run an LT1 T56 behind my 250 inliner and it takes a specific "pull" flywheel, not the standard flat flywheel. If I remember right a two piece seal SBC to LT1 T56 flywheel runs at least $400 (I run one on my 250) so one for a Caddy has to be up there in price as well and I'm sure entirely custom machined out of a 2" thick blank.

[SS Tim]

Take a good hard look at that trans deal. Stock early T56s had problems living in stock Camaros. It wasn't until the later post 2000 IIRC that things started getting better. If you are set on a Caddy engine just to "be different" then use a three or four-speed automatic behind it.

[68C15]

Longhornman had a web page years ago on his caddy swap.

mine is getting a NP A833 3 speed overdrive. I will run a racing bell housing since they have BOP and chevy patterns. I was thinking of taking a BOP flywheel and re-drilling the crank pattern. Then off the shelf parts will fit.

I'd like to take mine to a whole new level with fuel injection. I don't like aftermarket kits ($big). I'm still researching a way to amalgamate a few OE systems together. I did it years ago with a 235 straight six.

[Coley]

I like the idea of going with a 500 Caddy motor...very cool....very, very cool...and you will get lots of mileage out of the conversations around that at a show'n shine.
The LS motors are great motors and technically advanced but are complete 'yawners' at a hoods up show'n shine.
I agree tho' with going with an automatic trans on that application.
keep us posted on how it goes.
Coley

[no_rice]

Originally Posted by davepl

Different is good, but different is work. You have to make the call of whether the amount of work it's going to take is worth the ability to say and show a Cadillac motor in your truck. You have to do the calculus on that though. Just don't confuse an idea what feels exciting today with a project you're still going to want to be fabricating on 60% of the way in.

As for your username:

here is my ride that caused the user name.






i talked to cad500parts yesterday and they have a pilot bushing that goes into the hole already in the crank, they also have a flywheel from the caddy crank pattern to most normal gm clutch bolt pattern. yes the flywheel is like $450 or so...

he said they have had more then a few people do the t56 behind the caddy motor. a few viper setups, and the ls trans setups. that being said, he doesnt remember one being from an lt1 setup. but... the 94-95 trans i have is rated for 450tq factory spec. 93 and older were only 350tq. the later vipers were 550tq, but otherwise most of the 6 speeds were rated 400-450tq.

he also said that most of the guys they have had do that have used their custom pilot bushing, and their adapter plate which has allowed them to bolt the stock bell housing up to the caddy motor without a BOP bell housing...

believe me, i have some concerns about this swap, but i also know what my real use for this truck is, and its not racing, although i havent had it to a show either... just never been to big on sitting around all day. a couple hours at one and im ready to go. i think in the couple years ive had it ive only even spun the wheels a couple times. and ive never been big on clutch drops to produce tire spin.

i "believe" with the life it would lead, and the fact that its a stock motor it should hold together. that being said, if i need to i can always go back in and build the trans internals if that becomes a problem.

i still have alot of figuring to do, but i appreciate the input. whether it is for or against the swap.

[68C15]

engine rated torque is one thing. The work it does is another. For example a light Camaro will not abuse a trans the same way a truck will. Plus the caddy makes GOBS of torque right off idle. Kind of like having a bomb with a short fuse. The temptation to light them up while cruising at a steady speed will likely arise. "look dude, I'm in 4th and I can spin them without downshifting.

another great thing about the big caddys is the inherent fuel economy. They simply don't work hard at all so the MPG will surprise you.

[MARKDTN]

Originally Posted by 68C15

...another great thing about the big caddys is the inherent fuel economy. They simply don't work hard at all so the MPG will surprise you.

I had a '71 Eldorado with the 502. It got 11-12mpg whether you dogged it or babied it. The overdrive will help, but the truck is less aerodynamic than an Eldo and weighs about the same. I doubt you will get 15 or so even with the overdrive.

[jlaird]

I'm with you, I like different. Go with the caddy mill. If you still have questions, give Mike Forte a call from Fortesparts.com. I bought my Tremec from him. He knows his stuff and is a nice guy to deal with.

[ole dollor]

them older caddy motors were great , but I don't know if Cadillac would let you put a standard trans behind it.... to many old farts might complain ..

[no_rice]

Originally Posted by MARKDTN

I had a '71 Eldorado with the 502. It got 11-12mpg whether you dogged it or babied it. The overdrive will help, but the truck is less aerodynamic than an Eldo and weighs about the same. I doubt you will get 15 or so even with the overdrive.

i was looking up specs on the 2, and from everything i could find for curb weight, the eldorado out weighs the truck by over 1000 pounds!

either way, they are both like pushing a wall down the road.

im still researching. even if i have to build the trans at some point. itd still be fun. but that being said, if i set it all up for this motor and trans together in the truck, i'll be deep enough in that this will probably HAVE to stay in the truck forever lol.

[no_rice]

Originally Posted by low&slow

I put a 500 caddy in my truck with no issues at all. Turbo 400 tranny. If done right you won't need to massage anything on the firewall.

what did you do for headers on that? and a regular set of big block motor mounts?

[Dieselwrencher]

I say go for it! We used to have several early to mid 70's caddy's and the only time they got bad mileage was when you were doing burn outs with them. The old man's eldo may have been hooked to a pick up or two in high school and there were some pick up owners with hurt feelings.