Caddy Big Block in 67 C-10?

[72c10step]

I was wondering if I could get some input on this topic from some of the people on the board here. A friend of mine has a 67 C-10, and access to a (complete car, FREE!! ) 79 Cadillac with a 7 liter engine (425? I believe) that runs, and he wants to stick it in his 67 C-10. I know some of the guys on here have done this swap before, (Longhorn Man I believe has the same setup in his truck), and was hoping I could get some tips, advice, words of wisdom, things to watch out for, etc. for this swap. Is there any write up on this type of swap yet, and can any of you give us some pointers so we aren't going into this blind? Thanks

[Tx Firefighter]

I'm pretty sure Andy has a website describing his install.

[JAKES 68GMC]

Theres another member here with a Caddy BB in his truck, 71cadc10 is his name. Andy would be THE MAN to talk to.

[Jayss109]

ive got a 500 in mine as well. Heres some pics. Ive got more somewhere, but cant seem to find them at the moment.

http://web.mac.com/jason_hall/iWeb/T...%20photos.html
________
Honda integra dc5 history

[veedublu]

Nice pics Jayss109... did you dent your firewall to clear the driver's side head?

I would like to ask anybody with a running Cad-powered Chev what they are using for axle gears and what their thoughts are when it comes to performance? I'm considering 3.08's for mine... I want to run it down the highway once in awhile, but for the most part it will be an in-town playtoy. Tires will be 30" tall or just slightly taller (285/70/15). I do have a big cam, 10:1 compression, Edelbrock intake, and headers, so my truck might like a few more rpms than one with a stock engine.

I didn't do the standard motor mount idea of using stock Cadillac rubber mounts, I wanted something a bit cleaner and stiffer. Here is what I came up with:



Here is the engine in the chassis, can just barely see the mounts. I thought long and hard before notching the frame for the headers... could have run stock manifolds without cutting anything, but really didn't want to choke the engine down at all. I realize shorty headers aren't the best, but they are a heckuva lot better than the stock manifolds! Anyways, I decided that notching the frame was ok because it was right near the crossmember (and I'm running the 3/4 ton inner braces where the crossmember bolts on as well).



I did not dent the firewall for clearance, but it's gonna be a snug fit. I put a 500ci Cadillac into a '79 Toyota 4x4 and it was easier/had more room than this truck!

John

[68C15]

it looks sweet. I like the mounts. would you be interested in selling me a pair?

[JAKES 68GMC]

Those are some rugged motor mounts. Also one sweet looking Caddy.

[70c10]

Cool pic. How much power do these Caddy motors make in stock form?

[JAKES 68GMC]

The best ones were 68-71. 472's were 375 HP and 500's were 440 hp? I think the 68-71's had somewhere around 535 ft.lbs of torque. Research time....

EDIT: 68 472's had 375 hp and 525 ft lbs. of torque. The best 500 had 400 Hp and 550 lb feet, and that was in 1970.

Heres a caddy board. http://www.cadillacforums.com/forums/500-472-425-368/

Looks like theres some pretty good info, IMO.

[70c10]

Originally Posted by JAKES 68GMC

The best ones were 68-71. 472's were 375 HP and 500's were 440 hp? I think the 68-71's had somewhere around 535 ft.lbs of torque. Research time....

Day-um!, never knew that!

[Jayss109]

Man, looks sweet! Im still waiting on the guys doing some R&D on some shorty rear exit headers that should fit just fine. Im right by Sanderson headers, but they want $1500 to make me a custom set!!! Manifolds will do fine for now! =) Yes, I did massage the firewall a little bit for the head to fit into. This is my 2nd Cad motor, 1st one was bone stock, didnt change the timing chain, so all the nylon cloggged up the oil pickup and BOOM. Then save up for the 2nd motor, which is NOT stock. Hehe

I run 3.08s with a 29' tall tire. Cruise along at 2600 at 65mpg, figure about 2-300rpm for convertor loss. My enigine really seems to like cruising at that rpm, or 3000 (80mph) even better.

Can be a little scary when you realize that you can break the tires loose at 50mph. LOL Its a fun ride.

J
________
Trax

[veedublu]

Thanks for the kind words guys. When I get the truck closer to completed I will probably post a build thread. Right now all I have to do is run new fuel lines (down the driver's side of the frame) before the cab goes back on for the final time. Then everything should go pretty quickly, I expect to have it on the road in the next month or so (finances are the tough part).

68C15 - I'm not really interested in selling motor mounts. I've got way too much time into them - getting the angles right was pretty difficult... the Cadillac mounts are about 4" forward of Chevy mounts so the frame starts angling down as well as in, yet I wanted the bushing tubes to be parallel with the block. Unfortunately I didn't keep the templates I used to make these, so I can't duplicate them easily. Also, you might not want your motor exactly where I put mine... just too many variables to consider.

When talking about stock power output, don't forget they changed the way they rated horsepower in 1972, so the earlier motors look stronger in comparison to the later ones. The only real change was 1970 and earlier had right around 10 to 1 compression, later engines had approximately 8.5 to 1 (this applies to both 472's and 500's). In 1974 both engines got 120cc chambers in the heads vs the 76cc chambers of the '73 and down motors (with different pistons to keep the compression about the same). There were other slight differences (camshafts, etc) but nothing that made a huge difference in power.

Jay, what do you have done to your current engine? I'm really trying to nail down the gear ratio the first time around, and I can't find a whole lot of info on the Cadillac boards on where an engine like mine should "like" to cruise. It sounds like our engines may be similar, and it sounds like you're pretty happy with your 3.08's. How does it perform off the line? I'm looking to be able to fry tires at will, and usually 3.08's don't fit into that plan, but these big Cads don't produce the usual torque either

These are Sanderson headers, but just their standard block huggers (coated, of course). I have seen several pics of the "Cad600" header they used to sell (I guess they don't anymore) and it looks like one side would work for sure, the other side doesn't look much different than a block hugger. I'm sure you're aware you can buy Cadillac flanges to weld onto BBC headers? I probably would have gone that route except I already had these in the shop, figured I'd go ahead and use them if I could.

Thanks!

John

[lloyd k]

nice work, 3.08s would be about perfect, my truck had 3.42s in it when i got it and would run out of air really quick, put 2.73s in and it loves it, not much of a change in quickness if any, can run 70-80 mph all day long. my motor is fairly stock , but one with valve springs and a cam would pur with 3.08s. there are some guys running some very hot combos with that gear and big cad , hey Jayss109 you have another link to the pictures, cant find

[JAKES 68GMC]

If the V6 ever blow ups, maybe I'll put in a 500 Cad. That would be a hot ticket with 4.10 gears. Get a flywheel that will accept a clutch (325 bucks) and get a Buick/Olds/Pontiac/Caddy to Chevy bellhousing adapter, and I can run a 4speed! Yeeeee Hawwww.

[Jayss109]

Im at .30over, keith black pistons, 9.0-1compression, stainless valves, shaft rocker setup, stiffer springs...It is a later block/heads. Running MSD distributor, box, coil all the goodies. damn I cant remember all the specifics of everything. I had to have someone build it for me, cause, at the time I didnt have a garage!
I am running a 300T cam from Flashcraft. Well, cams and cads are like finding a pot of gold or some bs. Everyone if very secretive about their cam info, but It doesnt bother me any. Im headed out the door, but I'll post my cam card later. Hi lift and duration....its a big cam, just enough vaccum to run power brakes. I only have a edelbrock750, so I think thats the next upgrade... along with a bigger fuel pump. I dont think Im getting enough fuel into this beast! (Dont plan on any LONG jourenys without some stock in Chevron or something!

Even a BONE STOCK cad motor can burn the biggest tires off. Peak torque on a stockie is at like 1300rpms till 2200rpms. seriously, I would spins the tires, even when I didnt want too. That stck cam if Lame-o, but still more torque than a sbc!

Heres the link again, sorry I had played around with my site and forgot I had changed a few things.

http://web.mac.com/jason_hall/iWeb/T...%20photos.html

J
________
Headshop

[Jayss109]

Heres the info on my cam.

Lobe centers 112*, Intake opens 8* BTDC @ .05 lifter rise

Valve lift (with shaft setup) @.549/.549

Duration 286*/286*

Pretty lumpy, idles at 800rpms in gear



J
________
HONDA CR80

[Longhorn Man]

Wow... how the h*ll did I miss this thread?
Here is my site... I never really finished it, but it does show the basics I went through.
http://www.geocities.com/caddyoneton/
You do NOT want 4.10 gears with a caddy engine... I have them, and even with my 31 inch tall rear tires (235/85 R 16) it revs so quick I am throwing the torque out the window.
Here is a huge thread about this;
http://67-72chevytrucks.com/vboard/s...ad.php?t=20020
I love mine, and it feels kinda sick. I got another 425 headin my way and this 500 will be getting rebuilt.

[longhorn70gmc]

I love the way you made the Headers fit with out damaging them. Awesome! Good Job.
Respectfully

[veedublu]

All - thanks for your inputs on the gear ratio... sounds like I will do well with 3.08's

Jay, thanks for the additional engine info. Sounds very similar to mine, except I have the early heads, a touch more compression, and probably too much cam. I bought an MT15 cam from MTS - don't remember exact duration right now, but do remember it is 110 degree lobe separation, and .327 lobe lift (so .5232 valve lift with my 1.6 to 1 shaft rockers). I did install it 5 degrees advanced, wanted to keep some low-end.

Thanks again for the help with the gear ratio, and keep your eyes open for a build thread in the next few weeks... I finished the fuel lines and got the cab back on the frame on Friday.

John

[JAKES 68GMC]

Originally Posted by Longhorn Man

You do NOT want 4.10 gears with a caddy engine... I have them, and even with my 31 inch tall rear tires (235/85 R 16) it revs so quick I am throwing the torque out the window.
.

OK, maybe I'm having a brain fart on this one, but how would lower gears cut down your torque??

[Fred T]

With the torque/weight ratio a 3.08 posi should work pretty good with the smaller engine for a driver. With the 500 you could go with 2.73s. I hadn't realized Andy had 4.10s in his. You can't get enough traction in a pickup to keep the tires from spinning with those gears and that much torque.

[JAKES 68GMC]

OH, ok. I get it. If you have gears too low with a high-torque engine, then you are losing your torque due to higher engine RPM's. That makes sense. That would be the same theroy with a GMC V6.

[lloyd k]

depends what the rpm range is of your motor

[Jayss109]

With all them Cubes, she wants to "tug", not Rev.
Scary part is when you look at one of them huge pistons, and realize that they are actually bigger than most TopFuelers. Wheww, no replacement for displacement.

J
________
Shower video

[crazy longhorn]

Tug, not rev is right on! I ran both BB Caddy, & Olds in my longhorn, & they loved the snot out of a mid 3's gear(best of both worlds). My 383 is already gettin tired from spinnin those 4.10 gears.....not as big as the bad boys,but the 383 sb has a long flat powerband(tug ). My 383 is running 3.40 gears now, & a cool 5000 rpms is right on 120.....about a grand short of the red line tho! A big motor in one of these old trucks will run fast enough on the open road, to scare the chit out of this CRAZY old man(what the he!!, I like to be scared L