If anyone can help me I would appriciate it. I am getting ready to put a 1972 455 into my 1986 cutlass supreme and I could use some advice from anyone thats done it. Mostly Im concerned with the trans,drive shaft,exhaust, etc....

 

What trans are you going to use? Hopefully not your 200c

 

I have a 400 trans.

 

If you are using the 9'' tail shaft, you may have to move your crossmember, and if you are upgrading to an 8.5'' rear end you will have to get your driveshaft resized. I am doing a similar project this spring. I believe you can use your 307 motor mounts and it will drop in ok. 455 is an inch wider at the intake, but the motors are almost the same size. I'm not sure about A body headers on a G body, but this swap has been done a thousand times, and I'm sure someone else can clarify for you.
The guys on Realoldspower.com probably do this swap weekly. You'll probably find info on everything over there.

 

Thanks, If you find out anything elese let me know, and I'll do the same.

 

This is pretty much correct. The 455 has a taller deck height, so the engine is both wider and taller than the 307, but the motor mount locations and bellhousings are the same. The 307 accessory brackets will not fit on the 455. Prior to 1980, most Olds brackets were capable of fitting on both big and small blocks, but the 307 brackets are small block only. Note that the brackets, pulleys, and water pump must be a matched set. Olds used different water pump lengths and the pulleys must match.

Be sure to use the 307 motor mounts and frame mounts. DO NOT buy 455 motor mounts, they won't bolt to your frame mounts. As noted above, a TH400 with the short tailshaft will bolt up to the 200-4R crossmember location. Other TH400 tailshafts will require relocation of the crossmember. You'll need a double hump crossmember anyway if you plan to run duals.

 

My current project is dropping a 455 into my '87 Supreme, and pretty much everything they said is correct. Unfortunetly I don't have the cash to get started yet...exhaust and rear end build. According to my research the consensus is that the increased deck height on the 455 doesn't allow the air cleaner to clear your hood, so that's one thing you need to take into consideration. Apparently headers/manifolds are a tight squeeze, and the steering shaft gets in the way sometimes. Additionally, the whole rear end needs to be upgraded.


Hooker makes a set of headers specifically designed for this swap, but they cost just shy of $600. If you can find a used set, go for it, otherwise just buy what you want and beat on them until they fit...that's what i'm gonna do anyway

Hopefully I can start working on mine by FALL...

 

1 piece at a time my friend...... 1 piece at a time.
Start with your suspension and work your way up. Each shiny new piece of the puzzle will make you want to go to work the next day.

 

Nah, i've already determined the order I want to do things. I should have a good chunk of money by fall, the first thing I'm going to do is build exhaust and actually drop the motor & transmission. I'm building the exhaust by myself, all I need to do it is the money and a chop saw.

Since the 307 is shot, theoretically i should be able to drive the car around, and hopefully i don't turn my diff into metal shavings and snap the axle....as long as i don't stomp on it.

Then, the rear end job. I'm doing gears, diff, axle, and disc brakes in one job.

miscellaneous things along the way include trying to find beefed up front springs, relocating the shifter to the floor, installing a rev limiter, new gauges, and a hundred other things!

 

Like everything else that has been say about the swap, use the 307 Cutlass mounts, it will bolt up fine.

Get yourself heavy duty springs for the front. The 455 weighs 150 lbs more than the 307

 

Wait until you see its "stance" before you waste your money.

My information is: The actual difference (excluding intake manifolds) is more like 20 pounds.

Norm

 

I'll second that. I've done a number of big-block-in-place-of-small-block swaps and never had to swap springs. In fact, I usually end up cutting a coil off the fronts to lower the front end even more. If you want a good indication of how the car will sit after the swap, sit on the front fender and see if the stance is acceptable.

Note to Norm: While your ~20 lb number is probably correct for a 60s vintage BBO and SBO, the thinwall, windowed 307 is probably somewhat lighter. I have bare 455 and windowed 403 blocks in the shop right now. My precision Wal-Mart bathroom scale (built with only the finest Chinese steel and lead paint) says the 403 is 170 lbs and the 455 is 200 lbs. I'm guessing that the 307 is a little lighter still. Factor in the lighter crank, shorter rods, and smaller pistons, and the difference is more than 20 lbs. Having said that, your original point about waiting is correct.

 

Note: This is not a good idea if you are
obese,
have wet paint,
or have a chain on your wallet or pocket watch.

 

Ahhh, as my son would refer to it as "Chinese-ium". The best steel on the market.

 

Assuming A/C on the 403, we are looking at a 36 lb difference between it, and the A/C '70 455. Close enough to your 30.

Common knowledge.

And lighter heads. About twenty pounds lighter, for a total of 56? Lets call it 60 lb. Still a heluvalot closer to 20 than 150, which was my point.

It doesn't, however, excuse my failure to catch the A/C error.

Norm

 

I've seen similar numbers for Olds motors, but I'm curious as to the source of the chart. Some of the items just don't make sense. For example, 69 W-31s and 69 455s don't have aluminum intakes, so are these really 70 numbers or aftermarket intakes? Also, if you believe a big block aluminum intake is worth 35 lbs per the chart, why would a windowed 79 350 with iron intake be 46 lbs more than a 69 350 with aluminum intake? Since the difference in the block weight is in the 25 lb range for an SBO, the aluminum intake on the 69 should make the weights a wash. I guess we don't really know what "dressed" means - full accessories?

 

I though you'd never ask.



Norm

 

That wouldn't be the same Mondello who propagated the "offset engine" in the Supreme myth,, would it?

 

Step 2: With your left hand and the biggest effen screwdriver you can find, carefully gouge your connecting rod journals. Making sure to spell your initials in a grafitti-like fashion.

That #9piston is as big as the drag slick.

Drawing not to scale?

 

In fairness to Mondello, the drawing shows someone checking the thrust bearing clearance. Note the dial indicator on the crank flange. Note also that the main caps are NOT in place...

 

Aw dang.....
BUSTED!

I apologize for my mistake all

 

I don't know that Joe was responsible for it. Would have cost him a lot of sales revenue.

For what it's worth: His '97 catalog showed both Hooker and Thorley headers with the notation "will not fit convertibles".

Norm

 

I am looking to do the same thing with my 86 Cutlass. I want to swap the 307 for a 455.

 

I've got a 455 in an 87 supreme. I used the hooker super comp headers and fab'd my own frame mounts for the engine and the air cleaner does clear the hood with a torquer intake. I also put in an aftermarket double hump crossmember so I could run true duals. You can bolt in a chevy 12 bolt, easier to find and with the right aftermarket control arms they work very well. I also have moroso trick front springs and the stance is about 1/2 below stock. The only downfall with the hooker headers is that you won't be able to turn the wheels from lock to lock without rubbing, I went to the 3 1/2 weld pro stars but I think you can go to a 5 or 6 inch wide wheel and tire and it won't rub. With the stock 307 springs you should be ok with the ride heighth. let me know if you need any help.

 

will my 307 hei distributor work with 455 swap?

 

The stock 307 distributor is the CCC unit that does not have any advance mechanism. While it fits in the 455 block, you need to run the ECU to get any ignition advance. You'll want a conventional HEI with vacuum and mechanical advance built in.

 

Olds 307 to 455 swap can someone post wiring diagram will stock 307 distributor and wiring work?

 

will I need to bypass ecu with the conventional hei?

 

While it is possible to run the 455 on the computer, there really is no good reason to do it. Just pull the ECU and the associated harness from the car.

 

I bought just the engine with no ecu can I bypass stock ecu and just run a mechanical advance distributor ? Used mallory unilite distributor and coil worth $100?

 

will I need to modify anything if I disconnect stock hei and run mechanical distributor? Im guessing splice oil temp sensor into stock harness

 

You should probably stop guessing and get a factory Chassis Service Manual and Electrical Troubleshooting Manual. The latter has the wiring diagrams. The ECU harness is completely stand-alone. You can unbolt the computer and pull that harness completely out of the car. The oil and temp sensor wires are NOT part of the ECU harness.

 

For street use you want a distributor that has both mechanical and vacuum advance. If that Mallory Unilite is only mechanical, it's not your best choice. A stock 1970s vintage HEI is both cheaper and easier to get parts for, and it plugs into your existing engine harness (which is NOT the ECU harness). You'll need a non-computer controlled carb as well.

 

My '83 Hurst/Olds has a 461 big block with cast iron exhaust manifolds with Pypes 2 1/2" exhaust. It fits great with a G-Force cross member from Summit.
200-4R still in the car with 7 1/2" rear end. Runs low 13's; 13.30 in the heat. Carb and distributor are from '78 403 out of a Delta Eighty Eight.

Our '87 442 has a '78 403 out of a Delta 88 with Comp Cam kit and Hooker 2 1/2" dual exhaust running with the CCC hooked up and a Quadrajet carb built by Cliff Ruggles. Runs low 14's.
With the correct parts mixing you can make these car run acceptably. Remember to upgrade brakes once you start going faster!

 

Yeah I will thanks man. I was wondering how much the 200r4 and 7.5 rear end would hold the torque of the 455. Just getting situated with the distributor msd hei streetfire and wondering if I should of keep the stock qjet carb or edelbroxk 750

 

Do you have the stock 455's Qjet, then use it. The 307 carb can't be used without all the computer controls, unhooked it will be pig rich. Otherwise consider the 750 Street Demon for a new carb. The 2004R needs expensive upgrades to last and 7.5" is weak. The 7.5" spider gears are soft and mine exploded behind a mild 403 horsing around town, the exploding chunks took out the pinion gear as well. Yukon makes a hardened $70 replacement. The stock used set I replaced them with also looked questionable, noticeable wear. The Yukon spider gears looked perfect even after multiple mid 14's runs at the track with slicks. A better gear ratio, you are probably factory 2.56 and something like a Trutrac posi is a good idea. The spider gears are more just to keep it from exploding when smoking the tires playing around until you decide on your upgrades.

 

One of the weak points of the 7.5 is the crush sleeve. Supposedly lots of torque causes the sleeve to collapse, causing the pinion gear to move around. The fix is a solid sleeve and shims to set pinion preload. Other than that, and maybe a diff cover with preload bolts, I wouldn’t put any more money in a 7.5.

 

Of which include A/C pump and power steering.
If one wants to get technical, forged aluminum rods and headers would help even out weight differences even more

 

I currently don't have a spare 455 carb, my last 403 build I installed a new Jet Performance Quadrajet on my 5 speed Cutlass, it work great with an electric choke especially with 7a heads having the center port heat cross over filled with aluminum.

 

Needing help with vacuum connections 72 olds 455