[1980yellowbird]

My Yellowbird has a tired 231 V6 stock replacement. I really want to get a V8 in there. Of course, I'd prefer to have a 400 or 455 Pontiac engine, I'll probably end up putting a Chevy 350 in it. It has a th350 in it right now, which I'm told is different from a V8 th350. I think I'm going to put a 700r4 in and get the drive shaft shortened as well. Any tips/suggestions on engine or transmission selection, or from people who have tossed their 231 before would be greatly appreciated.

-Nick

[Lightfoot]

You may also use a Buick or Olds V-8 with that transmission. I was never aware that the 231 has a different TH350 than a V-8. That might actually be a metric TH200 or some such a unit. If it is a TH350, then I think it will work with a V-8 up to 350hp-400hp.

I bet you could get a running 403 for dirt cheap, and it will bolt right in.
A Buick 350/455 will be more friendly to your existing wiring harness though.

If you are used to driving the yellowbird with the 231, any healthy Buick, Olds or Pontiac 350 will be a great improvement, and you won't have bastardized it with a Chebby.

[1980yellowbird]

After looking a little harder, I found a guy with about 5 400's. He has a ~73 complete 400 from a Le Mans. It has a th400, A/C compressor and power steering pump as well. All of that is for $600. It ran before it was pulled a few years ago. Sounds like a steal, so I'm probably going to get that.

Just out of curiosity, is the Chevy 400 better than a Pontiac 400?

[72LemansFreak]

Originally Posted by 1980yellowbird

After looking a little harder, I found a guy with about 5 400's. He has a ~73 complete 400 from a Le Mans. It has a th400, A/C compressor and power steering pump as well. All of that is for $600. It ran before it was pulled a few years ago. Sounds like a steal, so I'm probably going to get that.

That's a heck of a deal. I'm glad you are not keeping your stock trans. Since your Firebird came stock with the 3.8, I'm going to guess that your trans is not a TH-350, but rather the Metric TH-200. It's a weak trans meant for weak 4-6 cylinder engines. I think it was used with some of the small V-8s, too. Either way, it won't live behind any 400 for long.

Originally Posted by 1980yellowbird

Just out of curiosity, is the Chevy 400 better than a Pontiac 400?

I think you know what answer you're going to get here!

Seriously, the chevy 400 was the largest small-block ever made. I think it was made from 1970-1980 and was used mostly in trucks, but was also put into full-sized cars/wagons in the first half of the 70s. The bores are Siamesed and if you use heads without steam holes, they can be prone to overheating. They made good torque, but not more than a Pontiac 400 could make!

With the 400 Pontiac/TH-400 combo, you've got a total sleeper.

[1980yellowbird]

Originally Posted by 72LemansFreak

With the 400 Pontiac/TH-400 combo, you've got a total sleeper.

I was thinking about getting a 4 speed O/D tranny as well. Would a 700r4 bolt up, or are their BOP varieties?

[72LemansFreak]

Originally Posted by 1980yellowbird

I was thinking about getting a 4 speed O/D tranny as well. Would a 700r4 bolt up, or are their BOP varieties?

That would require some more work if you want to go 700R4. You will need an adapter like this one:

http://www.tciauto.com/Products/Spec...apter_kits.asp

(scroll to the middle)

For the 700R4, the output shaft has a different number of splines, requiring significant driveshaft modifications.

I've heard the 2004r is a much easier swap and has both the Chevy and BOP bolt pattern. It has the same number of splines as the TH350. Almost the same overall length and can be built to live behind large engines.

For both transmissions, you will need to rig up a method to lock the torque converter. There are kits out there for that. Also need to have a way to hook up the throttle valve cable to the carb. This is critical! If that's not hooked up right, you will cook the trans in very short order. The mounting pad on your crossmember will need to be modified, too.

There are a lot of opinions about this, but I'm under the impression that the 700r4 is stronger stock than the 2004r. But going with a built 2004r is a MUCH easier way to go, even if the initial cost is higher.

Search the forums, I know it's been done by others. Everything I told you has been through research on this forum and elsewhere on the internet.

[1980yellowbird]

Okay, last few questions.

He said the engine could probably use a rebuilding soon, so I'd like to do that sometime in the summer. I'd like to get a lot of power, but I'd also like to spend no more than $2,000 on parts and machining. Any suggestions about what I should buy?

[72LemansFreak]

Originally Posted by 1980yellowbird

Okay, last few questions.

He said the engine could probably use a rebuilding soon, so I'd like to do that sometime in the summer. I'd like to get a lot of power, but I'd also like to spend no more than $2,000 on parts and machining. Any suggestions about what I should buy?

It's very possible to build a motor on a budget, but much of that depends on the condition of the engine. Obviously, if it needs a lot of machine work, its going to cost more, especially if you start getting into head work. If you want to do it right, you can't know what you need until you tear the motor apart. Sometimes it's more than you think.
For parts, there are lots of places you can buy them. Summit, Jegs, PAW, etc. Perhaps our sponsor sells overhaul parts.

Otherwise, that's a pretty vague question. What is your goal with the motor? Wheelstands? Cruiser? Fast street car? That will affect how much you spend.
Lots of factors to consider.