455/TH400 in 79 Cutlass

[tommytpk]

I'm getting set to repace the 260/TH200 with a BBO from a 74 Toronado engine (which was in a motorhome).
Just want to bounce some things off the people who have been there, and avoid too many surprises on swap day.

I bought motor mounts from a mid-80's Cutlass with the 307, someone here is shipping me a oil filter adapter from a 307. I am going to try to use my stock starter; I don't know if that will work or not.

I need to source bellhousing bolts, torque converter to flex plate bolts, trans coolant lines, and get a bigger radiator. I'm going to replace the timing chain and check the cover. I'm going to replace the oil pump with a high volume pump, but keep the Toro pickup and screen.

The motorhome had true dual exhaust, but I've heard that the driver's side manifold may not clear. The 455 hasn't been pulled yet, so I haven't had a chance to see the stamping on the manifold.

Finally, I got a great deal on a TH400, but it looks like a long tail. I read on 442.com FAQ section that "for a Cutlass, you want to get a short tailshaft TH400." Is that true? Why? Either way, I'm going to need a new driveshaft.

Any suggestions that fill in the blanks, or if I missed any thing, would be greatly appreciated. I'm exicted to do the swap, and add almost 200 CI to my Cutlass.

 

[Rktpwrd]

I've done the swap in my '80 Cutlass. Just at work right now, but if you can wait until tonight, I can help you out. Btw, the stock starter will work and clear fine.

 

[tommytpk]

No hurry, thank you!

 

[Rktpwrd]

I'm getting set to repace the 260/TH200 with a BBO from a 74 Toronado engine (which was in a motorhome).
Just want to bounce some things off the people who have been there, and avoid too many surprises on swap day.

I bought motor mounts from a mid-80's Cutlass with the 307, someone here is shipping me a oil filter adapter from a 307. I am going to try to use my stock starter; I don't know if that will work or not.

I need to source bellhousing bolts, torque converter to flex plate bolts, trans coolant lines, and get a bigger radiator. I'm going to replace the timing chain and check the cover. I'm going to replace the oil pump with a high volume pump, but keep the Toro pickup and screen.

The motorhome had true dual exhaust, but I've heard that the driver's side manifold may not clear. The 455 hasn't been pulled yet, so I haven't had a chance to see the stamping on the manifold.

Finally, I got a great deal on a TH400, but it looks like a long tail. I read on 442.com FAQ section that "for a Cutlass, you want to get a short tailshaft TH400." Is that true? Why? Either way, I'm going to need a new driveshaft.

Any suggestions that fill in the blanks, or if I missed any thing, would be greatly appreciated. I'm exicted to do the swap, and add almost 200 CI to my Cutlass.

Sorry for the late reply, and congrats on finding a TH400!
You'll have to bear with me on some of the finer details as I did my swap nearly 20 years ago before selling off my TH400 to help fund my T56 swap. I'm still 455 powered tho!
🙂
Bellhousing bolts should be easy, just 3/8" diameter by however long you need. You'll know once you have the transmission.

As mentioned earlier, stock starter (for the 455) will fit and clear no problem, but I'm not sure if your 260ci starter will fit the 455 block, or if it'll be strong enough to adequately spin it over fast enough.

Your 307 frame stands and stock 455 motor mounts will get it physically in place. Just bolt the frame stands in the existing engine crossmember holes for a 307 in a G body.

As for torque converter bolts, I personally would not skimp here, use aftermarket ARP bolts for that application for strength, reliability and piece of mind. Safety first!

Replacing the timing chain is an excellent idea as BBO's tend to stretch them pretty easily, especially if the engine is high mileage. I'm not sure what you'd be checking on the front cover tho, other than maybe for severe corrosion around the water pump area.

Exhaust is going to be your biggest hurdle to clear. It sounds like you're planning to run the stock manifolds (at least for now?), and there I can't really be of much assistance because I went directly to headers for my install.

They're a bit on the pricey side, but if you can afford them, Hooker headers p/n 3203 provide a trouble free fit. I can personally vouch for them, they are a BBO swap specific header for our cars and fit and clear like they're supposed to.

https://m.summitracing.com/parts/hok-3203hkr

If this is not an option for you, by all means try and see if you can make the manifolds work, but as you said there's conflicting information out there as to if they'll clear or not.

You will definitely need to figure out something for the transmission crossmember if you plan on running dual exhaust (which I'd strongly recommend), a G force crossmember for the TH400 is a sound choice IMO.

http://crossmembers.com/product/198...ino-cutlass-grand-prix-regal-crossmember-400/

As for the tailshaft length, my 400 had the short shaft, but from what I can recall it shouldn't make any difference in crossmember selection or anything else. You'll have to get a custom driveshaft made up anyways. Unless there's possibly an interference issue with the floor pan when using a long shaft...??
You'll need the 400 slip yoke mated up to your G body shaft, nows a good time to upgrade the U joint size and have it high speed balanced.

That's all I can think of for now, but I'm sure there's other stuff I've forgotten or overlooked. Any other questions or anything else I can help with, don't hesitate to ask. Always happy to help out.

Donovan

 

[tommytpk]

Thank you. since i have a toro 455, i was told the motor mounts wouldnt work, and to get 307 mounts. i was planning on keeping the stock frame pads that are in the car. is that going to be a problem?

 

[Rktpwrd]

Thank you. since i have a toro 455, i was told the motor mounts wouldnt work, and to get 307 mounts. i was planning on keeping the stock frame pads that are in the car. is that going to be a problem?

They (the frame stands) are for a 260ci Olds right? As long as they are, you're good. Believe it or not, all Olds motors are the same external dimensions other than deck height, that's why SBO frame stands will work to mount the 455.
Just get replacement 455 motor mounts for a car. My '76 Cutlass had them, you could use that as your application for the parts store weenies when they ask "what's it for??"

 

[oldsmobile joe]

i swapped out my 260 with a 455 many years ago. i used the stock rubber motor mounts and stands from the 260. 40.000 miles strong. for exhaust, i have repo w30 manifolds and custom formed exhaust. yes, i know i sacrificed some hp, but they seal well with no leaks.
joe

 

[Rktpwrd]

Thought I'd throw some pictures up for you for motivational purposes.

This was the 455/TH400 combo in the car after the transplant:

From a couple years ago, refresh and more HP and cosmetic improvements on the 455:

And reinstalled in the rolling chassis:

Hope these pics are of some inspiration for you. You'll love the increased power and torque, not to mention the bragging rights! Good luck.

Donovan

 

[ssn696]

Hope these pics are of some inspiration for you.

I can't decide which I like better - the chassis or the shop!

 

[Bar50]

I did an 87 Regal with a 455 Buick/TH400 from a big car, it had the long tail-housing, just cut a driveshaft to fit.