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I recently bought an 82 cutlass S that has a 350 rocket,turbo 400 in it already.has a 4 barrel holley..I'm looking to upgrade to a 1968 455 engine out of a 68 delmont...wondering will this engine drop in?and what kind of rear end work or gears would I need?I'm a newbie so go easy 😂..thanks
The 455 motor will drop right in and bolt up to the th400 trans .Be aware that the height of the 455 is taller than the 350 .if you are using a stock intake i think you'll be fine with hood clearance if you use a performer intake its doable but much tighter i had to get creative with an air cleaner to close the factory hood on my 80. regarding the rear end i still have my factory 7.5 rear in my car but we upgraded it with moser axles and a posi carrier from an s10 blazer with 3:23 gears .It has held up to the torque of the 455 for 2 summers now and i dont baby it.That being said i am still running 14 in tires which imo is easier on the rear. all bets are off if i were to put slicks on it and head to the drag strip. if i had the money i would have bought a ford 9 inch all set up for a g-body.
The 455 motor will drop right in and bolt up to the th400 trans .Be aware that the height of the 455 is taller than the 350 .if you are using a stock intake i think you'll be fine with hood clearance if you use a performer intake its doable but much tighter i had to get creative with an air cleaner to close the factory hood on my 80. regarding the rear end i still have my factory 7.5 rear in my car but we upgraded it with moser axles and a posi carrier from an s10 blazer with 3:23 gears .It has held up to the torque of the 455 for 2 summers now and i dont baby it.That being said i am still running 14 in tires which imo is easier on the rear. all bets are off if i were to put slicks on it and head to the drag strip. if i had the money i would have bought a ford 9 inch all set up for a g-body.
thanks for the response...the guy I bought the car from seemed to have been running the 350 rocket with the stock rear end as well...I've heard others say the 455 wouldnt be a whole lot different but I disagree...I've heard those rear ends are weak..have you done any modifications to your 455 engine?or is even the stock 445 from 1968 gonna give me more ***** than the 350?
Good point joe . Op do yourself a favor and use the w/z manifolds a lot less headaches .I rebuilt my engine it produces a little over 400 hp and around 500 ft lbs of torque(estimate)your 68 455 will put out considerably more torque than the 350 assuming both are stock .
Good point joe . Op do yourself a favor and use the w/z manifolds a lot less headaches .I rebuilt my engine it produces a little over 400 hp and around 500 ft lbs of torque(estimate)your 68 455 will put out considerably more torque than the 350 assuming both are stock .
thanks so much guys...did you use the w/z manifolds in yours?what do they cost and where do you order them?would these also fit the 350?
thanks so much guys...did you use the w/z manifolds in yours?what do they cost and where do you order them?would these also fit the 350?
I used the Thornton shorty headers on my build but it’s debatable if there is any real power advantages . The repop w/z cast iron manifolds are actually your cheapest option . I bought a set for my 76 I think they were around 350.00 at the time .
I used the Thornton shorty headers on my build but it’s debatable if there is any real power advantages . The repop w/z cast iron manifolds are actually your cheapest option . I bought a set for my 76 I think they were around 350.00 at the time .
what are the differences from these to the stock manifolds already on the engine?
what are the differences from these to the stock manifolds already on the engine?
looks like the thorntons have been sold out for a while..I wonder If it makes a difference in going with another company ..I'm reading thorton is the best for these
what are the differences from these to the stock manifolds already on the engine?
The stock manifolds from a 1968 Delmont have outlets in the wrong place. Again, they will NOT work in a G-body. The LH side is a center dump that will point straight down at the crossmember.
The stock manifolds from a 1968 Delmont have outlets in the wrong place. Again, they will NOT work in a G-body. The LH side is a center dump that will point straight down at the crossmember.
In your opinion would I get a bit more power with the 442 headers?what years would that be?
The W/Z manifolds were the best-flowing manifolds that Olds ever cast for the big blocks. They are internally divided into individual runners, like headers. They will clear the G-body chassis.
Real full-length headers (as opposed to shorty headers) will always make more power than manifolds. How much more depends on what else has been done to the engine. If you want to run headers for this swap, you need the specific BBO headers for a G-body.
The W/Z manifolds were the best-flowing manifolds that Olds ever cast for the big blocks. They are internally divided into individual runners, like headers. They will clear the G-body chassis.
Real full-length headers (as opposed to shorty headers) will always make more power than manifolds. How much more depends on what else has been done to the engine. If you want to run headers for this swap, you need the specific BBO headers for a G-body.
thanks alot Joe...great information...I appreciate it...I'm learning as I go...just trying to kind of get everything together while the motor is out and being worked on...I need to find out the rear end gears yet
Is the A/C still functioning on the 350? The brackets need extended to work on a 455. The 350 exhaust manifolds will fit but are restrictive.
a.c doesn't work ...I'm trying to track down w/z manifolds but the thorton ones seem to be hard to find...not sure what headers would work for this set up either...or what carb would be best ..rear end set up ..tires etc
imo the arh headers are the best they fit inside the frame rails and were specifically designed for the gbody .They run about 1400.00 or you can get hooker headers i dont like their design as one of the tubes wraps around the frame rail and a little cutting of the inner fender is a good bet.last i checked they were around 800.00. i dont know of any other header that doesn't need a beat down to fit .check this site and others in the classified section. the w/z manifolds come up once in a while maybe post a wanted ad here.Im a quadra jet guy i have 4 cars and they all run their original quadra jets and all work great.i rebuilt 3 of them with only minor tweaking. its your call on the rear gearing depending what you want to do with the car.keep in mind the 455 doesn't like the high rpm range so plan accordingly.
Get a set of non A/C alternator brackets. They fit the 350 and the 455. They go in the place of the A/C compressor. The also usually need the 5.6" water pump and corresponding pulleys. I have made them work with factory 6" water pump but it is a PIA as brackets need spaced out. Use the factory intake and Qjet, it will help a lot for fitment under the hood. The Qjet was factory tuned for your motor. Use your current manifolds if Thornton can't be found, the drivers side is the same hook up as the W/Z. The later catalytic converter cars had a straight down either 2 or the more common 3 bolt flange. If your motor has the 2 bolt angled outlet, early manifold, it is the same hook up as the W/Z manifold. You also want 2.5" dual exhaust. Also expect to upgrade your radiator. The GN radiator surround air direction rubber flaps help a lot for cooling on the G body. I finally added them, available and affordable in the aftermarket, it made a noticeable difference along with the wider A body rad which needed minor trimming to the core support. I wish I did it when I had my 403 in the car. Good luck.
Space the brackets because you don't want to get the correct water pump or pulleys? And go through all the trouble to swap a 455, then constipate it with the 307 exhaust manifolds? Why not run a 2bbl while you're at it? And no, the 307 manifolds on a BBO do not put the outlets in the same place as the W/Z manifold, so now you've paid for a custom-bent exhaust system that you have to trash when you decide that you are giving up too much performance with the crappy manifolds. Yeah, good plan.
Space the brackets because you don't want to get the correct water pump or pulleys? And go through all the trouble to swap a 455, then constipate it with the 307 exhaust manifolds? Why not run a 2bbl while you're at it? And no, the 307 manifolds on a BBO do not put the outlets in the same place as the W/Z manifold, so now you've paid for a custom-bent exhaust system that you have to trash when you decide that you are giving up too much performance with the crappy manifolds. Yeah, good plan.
307 manifolds
W/Z manifolds
i have done or been involved with dozens of BBO into G body swaps, Joe’s advice is right on the money.
The G body manifolds “fit”, just not very well, and don’t flow all that great. What’s the point of swapping in a bigger engine that can’t breath?!
I have resisted the Hooker header swap, until my brother in law bought a pair. They went in surprisingly easy, and if you play around with wheel offset they really don’t hurt the turning radius all that much. Granted, he was rolling with the old school “big n little” tire stance. Swapping in a F body steering gearbox helps also, the internal steering radius stops are tighter than the G body car. That limits the turning radius, preventing tire/exhaust contact.
Do it right, or leave it alone. There are enough cobbled together cars at the track and on the road as is. What’s the point of building a fun car if you can’t enjoy it?
Does it have 307 manifolds on it right now? It has a 350 swapped in with a TH400, far from stock. Only the starter of this thread knows for sure, it could have early 350 manifolds. Again, this swap isn't completely direct and needs a bunch of donor parts to complete. Yes, he needs different brackets, pullies and a water pump. In his case, he should get the right parts. I got my 70S with a 260 had a long water pump, non A/C brackets and mix matched pullies. Finding a complete set of everything isn't so easy, he will have to do some searching. Very few later cars were non A/C, so Oldsmobile parts hoarders will be needed for the accessories. What if he can't find W/Z manifolds? Everything is in short supply. His car runs, gather parts, see if he can find it all, it might take the rest of the year to find everything. Then there is the wonderful, weak 7.5" rear end that still needs addressing.
Yet we can guarantee that it doesn't have BBO manifolds on it now.
My whole point was if early 350 manifolds are on the car and he really wants the swap done now, any exhaust will transfer right over to the W/Z manifolds. Same with the belts, I spaced out the alternator on my 70S because I had 3 long water pumps and at least it wasn't throwing belts and squealing like the former owner left me. I am lucky the car made the 6 hour drive home without belt issues, started almost right after that. If he has the A4 compressor with the motor, he can leave it dead to keep belt alignment. I am doing that on my 70S with the sbc serpentine setup. When I add A/C, it is not getting a POS R4 compressor, there are Sanden conversion brackets. I hope the W/Z are available, call first, I bet they don't have any on the shelf, hopefully I am wrong. Good luck
My whole point was if early 350 manifolds are on the car and he really wants the swap done now, any exhaust will transfer right over to the W/Z manifolds.
No, it won't. The W/Z manifolds are taller than the SBO manifolds. When bolted to the short deck small block, the early SBO manifolds have their ports at the same height relative to the crank centerline as the W/Z manifolds do when bolted to a tall deck BBO. Put those SBO manifolds on a BBO and the outlet flanges are an inch higher up relative to the crank centerline than the outlets on W/Z manifolds on the same tall deck motor.
No, it won't. The W/Z manifolds are taller than the SBO manifolds. When bolted to the short deck small block, the early SBO manifolds have their ports at the same height relative to the crank centerline as the W/Z manifolds do when bolted to a tall deck BBO. Put those SBO manifolds on a BBO and the outlet flanges are an inch higher up relative to the crank centerline than the outlets on W/Z manifolds on the same tall deck motor.
That makes sense, interesting guys have made the Pypes and Ramair Restorations down pipes designed for the BBO fit the 350 and 403. There are pics on this site to prove it. Didn't those regular manifolds come on later 455's? I assume they used a different, longer crossover pipe on single exhaust. Again, it still leaves the weak 7.5", I broke mine twice with a 403. The stock spider gears are soft and explode.
looks like the thorntons have been sold out for a while..I wonder If it makes a difference in going with another company ..I'm reading thorton is the best for these
