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-   -   Cadillac 390 to Chevy 350 Engine Conversion (http://www.hotrodders.com/forum/cadillac-390-chevy-350-engine-conversion-115548.html)

62cadillac 05-07-2007 04:19 PM

Cadillac 390 to Chevy 350 Engine Conversion
 
I have a 1962 Cadillac with a X-Frame Body and would like to see if anyone has any pointers on converting to a Chevy 350 Small Block Engine?

matt167 05-07-2007 06:10 PM

why not upgrade to a 500 caddilac?

curtis73 05-07-2007 08:32 PM

good point; about the same cost when you consider its mostly a bolt-in and waay more torque, plus you won't have to change trannys. I just sold a running 500 for $50

Converting to chevy is no problem with a bit of drilling/welding, but you'll need a different tranny, and chances are the caddy tranny is the super long tailshaft. You'll need a different driveshaft, different tranny, engine mounts, etc.

joe_padavano 05-08-2007 12:21 PM

Quote:

Originally Posted by curtis73
good point; about the same cost when you consider its mostly a bolt-in and waay more torque, plus you won't have to change trannys. I just sold a running 500 for $50

I'm pretty sure the 62 tranny uses a different bellhousing bolt pattern than the BOP pattern on the Caddy 500. Even the 64-66 Caddy TH400s used a unique bolt pattern and do not interchange with any other GM motors.

oldbogie 05-08-2007 01:34 PM

Quote:

Originally Posted by 62cadillac
I have a 1962 Cadillac with a X-Frame Body and would like to see if anyone has any pointers on converting to a Chevy 350 Small Block Engine?

You will feel the loss of torque big time. But the only real problem which is simple to fix is the engine to bellhousing bolt pattern. Adapters can be had.

But if I didn't want a caddy motor, I think you'd be happier with a big block Chev in there.

Bogie

joe_padavano 05-08-2007 02:06 PM

Quote:

Originally Posted by oldbogie
But the only real problem which is simple to fix is the engine to bellhousing bolt pattern. Adapters can be had.

Don't bet on it. The 62 trans uses a different bolt pattern than the later model BOP transmissions. Adapters are NOT readily available.

matt167 05-08-2007 05:38 PM

Quote:

Originally Posted by joe_padavano
Don't bet on it. The 62 trans uses a different bolt pattern than the later model BOP transmissions. Adapters are NOT readily available.

adaptors can be made for anything. there are company's that will make them custom. my friend had 1 done by a guy ( 1 man company ) in Washington

Deuce 05-08-2007 06:04 PM

I like 350 Chevrolets as good as anyone and better than most but WHY ???
The Cadillac is heavy ... and needs a lot of torque to get moving. If you must change engines ... find a later, bigger Cadillac engine ...

Trust me ... :thumbup:

Trans Am Tony 05-09-2007 12:16 AM

I would buy a 500 Caddy and put the 472 heads on it. Hot Rod magazine did that in an issue a while back, and got over 500 lb/ft of torque running 91 octane. They put that monster into a 1978 Chevy Chevette (required full rollcage, removing the firewall and other major mods). It was a BEAST!!!!!!!!!!!! :D

joe_padavano 05-09-2007 08:44 AM

Quote:

Originally Posted by matt167
adaptors can be made for anything. there are company's that will make them custom. my friend had 1 done by a guy ( 1 man company ) in Washington

Agreed, but responses to this thread had implied that a 500 would bolt up to the 62 trans or that you could use a BOP-to-Chebby adapter available from Summit to install the SBC. Most seem to be unaware that the 62 Caddy trans and engine used a unique bellhousing bolt pattern.

62cadillac 05-09-2007 03:40 PM

well my main concern was to find something that anybody can work on for cheap. I've already purchased a 350 Chevy Engine and 350 Turbo Trans to do the swap. I'm not trying to build a Race Car or anything, just a Daily Driver that I can depend on.

oldbogie 05-10-2007 11:47 AM

Quote:

Originally Posted by joe_padavano
Don't bet on it. The 62 trans uses a different bolt pattern than the later model BOP transmissions. Adapters are NOT readily available.

Thanks for making me realize how ancient I've become. When first reading the thread, I couldn't understand all this talk about not being able to mate a Chev engine to a Hydro-Matic. I knew that B&M made an adapter, I could see it in my minds eye. So I went to the B&M site but couldn't find a reference. When I got home, I pulled the old B&M catalog off my bookshelf and looked it up and sure enough, just as I remembered, there it was! So I plugged into the web at home and fed it the B&M part number, nothin'. So I went back to the catalog thinking I messed up the part number. At that point I realized the musty, tattered, brown paged catalog was 45 years old.

Great, just great! Now it has tear stains to go with its aged pages.

Bogie

joe_padavano 05-10-2007 02:17 PM

Quote:

Originally Posted by oldbogie
Thanks for making me realize how ancient I've become.

Great, just great! Now it has tear stains to go with its aged pages.

Bogie

Yeah, getting old is a ******, but it sure beats the alternative... :thumbup:

62cadillac 05-11-2007 03:33 PM

So does anyone know of anything I need to look for with doing the install or have any tips/pointers that might help me get it done?

oldbogie 05-11-2007 04:23 PM

I think we pretty much bashed this idea into few options for you.

The limiting factor is the old Dual Range Hydro-Matic transmission. It only bolts to pre-1964 engines. The new 64 up BOP-C bolt pattern on the block doesn't accept the older bell-housing. The Chevy bolt pattern is different again and while it possible to purchase Chevy/BOP-C adapters; the only source of 64 and up BOP-C or Chevy to Hydro-Matic transmission adapters has long ago dried up.

This limits you to using a pre-64 Caddy engine, there's worse things in life, if you want to retain the DR Hydro-Matic. Or:

1, You get lucky and find an old B&M adapter Chev to DR Hydro-Matic at a swap meet, Hemmings, e-bay, something like those places. Or you stumble into a 64-up adapter for BOP-C which would let you use the more modern Caddy V-8s.

2, You change to a TH-350/400, 700R4/4L60, 4L60E/4L80E gearbox which will let you run any modern GM V8. Once again this is simpler as Chevy to Chevy; but Chevy can be commercially adapted to 64-up BOP-C and some of these came with both bolt patterns.

Lastly you need to realize that the Cad's value to collectors goes way down with any non numbers matching engine and a non-original type transmission. So I guess before breaking the numbers matching stream you have with the 390, it would have to be a basket case before I go down that road.

If you don't care about numbers matching and want to be in a world where parts are available at reasonable prices, my modern response would be a BBC with a TH-400 or if wanting more recent technology, still a BBC with a 4L80E. The latter gear box will give an overdrive 4th combined with a lock up converter for really efficient, slow RPM cruising. Plus it has a really deep low, like your DR Hydro-Matic, to launch this heavy car. If you went for a fuel injected BBC this would be a super set up.

You could do a 350 or even a 383, but from where my experience has been, when you talk a car that's as heavy as a modern 3/4 ton pick up, you'll be happier, longer with the engine and transmission from the 5000 pound truck. It's not that you can't get power out of a SBC, but asking it to that and move 5000 pounds of vehicle really reduces its life span. Besides a 350 just wouldn't have the torque to launch the Caddy, espacailly with a TH-350 transmission. which has almost a ratio higher low gear and no OD. Getting the Caddy launched takes a lot of torque, this really takes some cubic inches from the engine where a long stroke is better at torque on the bottom end where it's needed with this rig; and it takes some steep gears to help get it launched. I think an SBC with a TH-350/700R4/4L60/4L60E is in over their structural head. I' mean they'll do, but it just won't last.

Bogie


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