I picked up a 81 cutlass with no motor or trans with a ford 9 inch with 3:70 gear ratio and strange axles. I plan on putting a 455 olds an th400 in, that i built in highschool i now have the time and money to finish it. the reason im asking questions is that the more i research this project the more confused i get. I know this is the place to talk to guys that have already done this swap. From what i know the guy had a 427 th350 in it but it all looked shady it seems like the motor mounts are way far forward on the frame. It also looks like he bashed in the ac box and re glassed it, it looks like crap. i plan on buying an ac delete plate, If i use the 307 motor mounts will i be able to use a set of flowtech 403 headers
81 cutlass 455 swap i could use some help
- Thread starter Big block WI
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You will need to use the motor mounts and frame mounts from any Olds 307 powered G body. Depending on what valve covers you use, you may or may not need to make room to clear the heater box. It also depends on what type of intake you use that will determine if you have hood clearance problems. In most cases you will not be able to use the 403 headers o a big block, but you may get lucky and they might fit. You most likely will have to get headers that fit a big block though.
You'll also need to get a new crossmember for that TH400 (since you mentioned it had a TH350).
307 mounts are perfect, just make sure you get them in the correct holes, since there's about 13 different holes to choose from on the frame.
SBO(260-403) headers will not work, otherwise I would have used the set I had laying around myself.
You're stuck with either manifolds, or Hooker Super Comps (which I ended up getting), and there's one other company out there making them, but I can't remember which one.
Clearance for the A/C box won't be an issue unless you're running tall valve covers, and I always urge people to reconsider before eliminating them.
You might think it's a summer-only car, but you know as well as I do that it gets chilly at nite during the summer too, not to mention it's nice having the fan/vents to keep the windows clear if you're caught in the rain.
If the looks of it bother you, find another box to replace it. They're all the same through the entire 78-88 G-body line, so take your pick. I bet there's a dozen to pick from at your closest yard.
I'm right next door to you in MN, and I'm damn glad I have heat in my car.
Not to mention it is a big detraction if/when you go to sell the car.
I've walked away from several potential purchases because people had removed the heaters from something that I wanted to drive year-round...
307 mounts are perfect, just make sure you get them in the correct holes, since there's about 13 different holes to choose from on the frame.
SBO(260-403) headers will not work, otherwise I would have used the set I had laying around myself.
You're stuck with either manifolds, or Hooker Super Comps (which I ended up getting), and there's one other company out there making them, but I can't remember which one.
Clearance for the A/C box won't be an issue unless you're running tall valve covers, and I always urge people to reconsider before eliminating them.
You might think it's a summer-only car, but you know as well as I do that it gets chilly at nite during the summer too, not to mention it's nice having the fan/vents to keep the windows clear if you're caught in the rain.
If the looks of it bother you, find another box to replace it. They're all the same through the entire 78-88 G-body line, so take your pick. I bet there's a dozen to pick from at your closest yard.
I'm right next door to you in MN, and I'm damn glad I have heat in my car.
Not to mention it is a big detraction if/when you go to sell the car.
I've walked away from several potential purchases because people had removed the heaters from something that I wanted to drive year-round...
Blake442 said:
I have seen sb headers work on a big block before. It was tight, but it was not that big of a hassle to make them work. This was not in a g body though. Don't know what brand they were.
dan2286 said:
Exactly.
There isn't enough clearance between the motor and the frame, not to mention that the taller deck height of the 455 versus a shorter 403 will change the already tight tolerances for space.
The primary tubes are already right up next to the frame rails, now potentially moving them up and out puts them into the space that is occupied by the frame.
I'd rather buy the proper headers than notch my frame to clear the wrong parts.
a cutlass with a ford 9 inch and 3.70 gears is a perfect start!the 455 will need to use the 307 v8 motormounts,any other body style other than a g body will not line up right and you'll have a lot of problems in the future.If your deleting a/c,please dont buy a $70 piece of metal,I've made one of these a/c delete panels,all you really need is roughly 4 hours,cardboard,pencil,scissors,air driven cutoff wheel and a $20 piece of metal from the hardware store.I have a pic of it too,its up to you if you have the money to buy the panel and bolt it up or make one for a fraction of the price.
BTW it will come out nice if you have a lesser shakier hand
BTW it will come out nice if you have a lesser shakier hand
I agree with Blake. Keep the AC/heat in the car. There's nothing worse than getting caught with no defrost when its raining or chilly out.
As said, you'll need both the 307 frame mounts and 307 engine mounts to drop the 455 in place. You use the holes furthest back towards the firewall on the frame.
As far as headers, the SBO headers may or may not fit. I know there's people that have claimed they got them to fit but they are NEVER able to give a manufacturer, etc. for the headers. They're usually just something they had laying around.
The easiest thing to do, probably the best for a street 455 would be to use a pair of W/Z manifolds. Plenty of guys running in the 12's with just manifolds. Other than that, you can go with a set of headers from Dick Miller Racing. The headers were formally made by Kook's but Dick Miller bought out all of they're Olds jigs and patterns.
The nice thing about these is that they fit inside the frame rails unlike the Hooker Super-comps which in my opinion are a total waste for a street car.
I have a set of the 2" primary, 3.5" collector Kook's headers on my 455 and they are absolutely one of the best fitting headers I've ever seen. They are also one of the more expensive headers as well. 🙁
As said, you'll need both the 307 frame mounts and 307 engine mounts to drop the 455 in place. You use the holes furthest back towards the firewall on the frame.
As far as headers, the SBO headers may or may not fit. I know there's people that have claimed they got them to fit but they are NEVER able to give a manufacturer, etc. for the headers. They're usually just something they had laying around.
The easiest thing to do, probably the best for a street 455 would be to use a pair of W/Z manifolds. Plenty of guys running in the 12's with just manifolds. Other than that, you can go with a set of headers from Dick Miller Racing. The headers were formally made by Kook's but Dick Miller bought out all of they're Olds jigs and patterns.
The nice thing about these is that they fit inside the frame rails unlike the Hooker Super-comps which in my opinion are a total waste for a street car.
I have a set of the 2" primary, 3.5" collector Kook's headers on my 455 and they are absolutely one of the best fitting headers I've ever seen. They are also one of the more expensive headers as well. 🙁
Thanks alot for the info i rechecked the box they came in and they are long tube headders it says they will fit on 350-455 olds the only thing im worried about is they are more than likely for an A-body car. I have stock height eldelbrock valve covers so should i just buy a new ac box from a local junkyard. It has a aftermarket transmission crossmember with multuple bolt patterns if it doesnt work I have two parts cars that used to have 3.8's in them will they work? I did plan on getting a 4" cowl for the car i found some fiberglass bolt ons on ebay i was wonderin if anyone has ran these hoods they're made buy glassworks?
Big block WI said:
I tried A-body headers on mine years and years ago. I cut the heck out of them and they still didn't fit. Too many tubes had to be rerouted to clear the chassis.
That's what I'd do. However, when I installed my 455 years ago, I had issues with stock height valve covers hitting the AC box and had to cut and trim it to install the engine. Years later when I started my frame off I realized the problem was the fact my body bushings were shot and the car was sitting lower on the passenger side.
Depends more on what transmission they have behind them, not so much what engine. I believe the TH-400 uses the same crossmember as a TH-2004R. In which case you'll also need a frame extension for the drivers side frame rail as your '81 won't have it.
I didn't see any by glassworks but did see a couple made by Glasstek. Glasstek is arguably one of THE best fiberglass hoods you can get. However, if your just getting the hood to clear the engine, you should be fine with a stock hood.
Where are you located???
I have a set of G-Body headers for a 455. They are like new and in VERY good condition, Hooker Super Comps. Big tubes, I will let them go cheap but don't want to fool with shipping them. So let me know.
Thanks,
I have a set of G-Body headers for a 455. They are like new and in VERY good condition, Hooker Super Comps. Big tubes, I will let them go cheap but don't want to fool with shipping them. So let me know.
Thanks,
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