I have an '85 Olds Toronado that I bought from the estate of the proverbial little old lady.  The interior is beautiful, it has every option save the telescoping steering wheel, and best of all everything works (except the electric antenna and low wiper fluid sensor).  The body is straight (it needs new paint) and it is a pretty good 20/20 car, i.e., it looks real good from more than 20’ or going more than 20mph.  It is a great couch on wheels.  I like that it is different.

However, it moves at what I like to call a stately pace...

I would like to replace the anemic, oil consuming 307 with a mild 350.  The problem is that I have no clue what the oddball TH425 transmission and front drive system can take or if the innards of the transmission are common enough that it could be strengthened with minimal pain.  I am also not real sure what engines would bolt in.  

Can anyone clue me in?  

In my ideal world, an army of nubile mechanics tastefully overhauls my car, cooks nice meals, keeps the house clean, and finds me irresistible...  In the real world, I would like to buy a crate engine complete with intake, carb, etc., that will bolt in with minimal pain and not overwhelm the transmission.  Note, I am not looking for a fire-breathing, lumpy idling, beast from the dark side of Detroit, but I get the hint when the guy in the VW microbus passes me.

I admit openly and without shame that while I am handy with a wrench, I have never built an engine from scratch and would rather carry the transmission to a good transmission man.  I have pulled heads, replaced timing gears, etc., on cars, tractors, and bikes and I am not afraid to get my hands dirty.

I don't know about your tranny but when you say "350"  if you mean Chevrolet 350 it will not bolt up to your bellhousing.  Buick/Olds/Pontiac or BOP used a different bolt pattern for this.  In the event you did mean chevy 350, it wouldn't be that hard to find a TH350 and just replace the tranny as well.  

I dont think a t350 will fit. arent those car FWD?  

I dont have any numbers, but I've seen plenty of Toros with 455s and stump pulling amounts of torque. So I'd have to say that the transaxle can probably live behind a fairly stout motor.

And yes, and Olds 455 will drop right in.

Yes they were front wheel drive...which I would think makes a chevy 350 very difficult to drop in since it does have a fwd tranny with a BOP bellhousing.  A 455 would probably drop in, maybe a few clearance issues since its a wider block, but the 350 Olds will drop right in place of that old 307.  That would be the easiest thing to do...I would think the tranny would hold up fine...you said it was a TH-425 right?  From what I've heard, the turbo hydromatics were named based off their torque capacity i.e. a TH350 was rated to hold 350 lb-ft a TH400 would hold 400 lb-ft...etc.  So just based off the name...it sure beats a TH200 or 200-4R in the rear drive specimens (at least stock).

Good Luck

It's a drop in, and the trans will be fine. It's  related to the th440/4L60. Has a lockup converter.  

What I mean by "350" is that I want something more than a 307 that will fit in the hole without too many issues.  I was guessing an Olds 350 or 403 would fit the bill.  The tranny does indeed have a lockup converter and is a 4sp -- and a forward output that is offset to the driver's side and bolted to a differential powering the front wheels.  

The responses about the transmission make putting an engine in more palatable.  

So, now for some questions that will rank me as a complete novice:  Where is a good place to look for an Olds 350 or 403?  I would frankly prefer to start with, at a minimum, a short block and a list of parts that will make good power without having to reinvent the wheel or end up with a combination that will not work.

Any clues on that?

Ok - I can't resist - sorry CSI was gone for awhile -

The absolute best Olds 350 you can have are the first run ones out of '68 and '69 Cutlasses and 88s.  They had the 330 block with steel cranks and rods and were bored over to get to the 350 CID.  They have the best geometry of any GM Engine I am aware of.  They were oversquared almost to the same extent of the early 400's .  Give me 24 hours and I can give you casting numbers and where to look for them.  Actually the casting numbers are the big numbers right next to the oil filler spout.  I will get them out of my notes.  They are at my office since I was talking Olds stuff with another guy who is building a 350 mill where I work.

I can also give you the numbers for the 330's.  They were only made from '64 to '67, and are becoming fairly hard to find.  They are like hammer mills that never die - came from the factory with forged cranks, and other stuff that kinda set them apart.  I have one in my '67 Cutlass that I have mentioned here on this board before.  They are tough engines.

As for the big block - I would bag it.  You could probably shoe horn it in there, but then you would have issues with springs in the front of the car (extra weight) and stuff like that .  On one of those Toros it would be a major pain.

Will get back to you tomorrow.  Like someone else says - "Keep it Olds".  You are going to have a nice ride.  Bowser

You could but a reman unit from any number of places, as a short block. And in most cases you can specify a cam of choice. Use the Edelbrock RPM heads, and performer intake.
On a 403, this would be quite the torqer, and likely 300+ hp. Top it off with a massaged Q-jet, and some kind of dual exhaust. Should be quite capable os boiling the fronts right off the car. Likely will fly n the highwat, too.  

I think I can give you some information that may help in picking what engine (or at least what 350) to use.

First, it needs to be stated that the early blocks (say up through 1973 or 1974) contained high nickel content cast iron.  This made the blocks much more durable.  I think I mentioned that my 150,000 mile 400 short block out of my '68 442 still has hone marks in the cylinders the entire length and no noticeable ridge.  High nickel content is the direct reason for that, along with regular oil changes, so the earlier blocks are better and wear longer.

Casting numbers to look for are 381917, or a 395558 followed by a small 2.  If the number is followed by a letter (such as A, B, C etc), it's a big block but you are wanting to go with the 350, so just be aware of the difference. 

I was corrected by my son who let me know under no uncertian terms that I made a mistake in my last message.  The cranks in the early 350s are not steel, they are nodular iron which isn't as good as the forged ones out of the 330, but are a close second. 

Starting in 1972, smog and emissions became an issue, so compression ratios dropped.  This was usually achieved by increasing the combustion chamber size on the head.  Large CC heads can be replaced with smaller CC heads to correct this.  My sons 8.5:1 350 in his '72 Cutlass should be brought up a full point or more after we install some 330 heads.  They are #4s, and have smaller CC chambers and larger valves.  They were already rebuilt and I got them from a friend for a good price.  It should net a good HP and Economy gain on the engine.

#5 heads are touted to be the best flowing and net the best compression ratios of around 9.5 or 10:1.  I wouldn't disagree with the idea of using aftermarket aluminum heads.  First of all, any old set of heads you get are going to cost you around $700 - $800 to fix up anyhow.  If you can expend the money aluminum heads are great, but either way you are going to have good heads for your motor. 

If you happen to run into a 350 out of a W-31 Cutlass that is actually for sale, BUY IT.  Those engines were built from hand picked parts, and each one was built by hand by one technician.  The chances of finding one are almost slim to none, but I have found components for them like on Ebay.  Some guy was selling the rods and pistons out of one.  The pistons were probably trash, but the rods would have been the crem de la crem as rebuild stock. There were no scuffs or marrs and probably could have been used as is.  (I had to resist.....My wife is already pissed that our wardrobe walk in closet is full to the ceiling with car parts).  Not many people realize that the W-31 actually spanked the pants off of a W-30 in 1969 during corporate road testing.  It was long a secret because the W-30 was supposed to be the fastest and best.

Mondello has some great how to books on building performance Olds engines.  Just the Mondello catalog is good reading.  You can find stuff for Olds there that you cant find any where else.

Well, I hope this helps you in your engine shopping and junk yard hopping.  Hopefully you will end up with a screamer like mine.  They are fun.

Good luck,  Bowser 

Hate to burst your bubble, but the W-31 engines were not hand built. Yes they were a factory "blueprinted" engine, meaning that tolerances were kept tight, and they were better than normal balanced. As a Lansing, Michigan resident(born and raised), and as the grandson of a 40 year GM worker, who worked for Olds his whole career. I have met the people responsible for alot of the original Olds performance stuff. They were built on the assembly line, along with all the rest.  

Didn't think that was the case.  If you live in Lansing and have relatives that worked at GM, I won't argue.  Where I heard this was from a retired Olds engineer that was speeking to the subject on the Speed Channel only a few days ago. I mentioned it because I never heard it before either.  He could have been BSing I suppose.  The statement that the W-31 spanked a W-30 I stand by.  That has been broadcasted, written about, and talked about in too many circles for too long to be incorrect.  I only wish I had an honest to goodness W-31 to my name.  The ones that have been selling on Ebay and some of the other internet sellers are somewhat questionable.  Someone would really have to check one out in person to be sure there wasn't any tom foolery going on.

Regards - Bowser