427 swap

[Wilson]

Very new to forums and have never posted before. Please be patient with me.

I have a 1988 Monte Carlo SS with a pretty disappointing 305 in it right now.( not the stock one, and no where near running right). I have been wanting to do something with it but wasn't sure how I was going to give it more power. A friend of mine has found a pretty ridiculous 427(about 600hp) at a bargain price ( there's a reason why it's a bargain not a junk motor or amateur builder). But I have never thought about putting a big block in this car. Is there a lot of fabricating involved in a big block swap? Can these cars handle that much? I know the trans and rear end will need to be done suspension and brakes upgraded, but am I just going to twisler the frame? I don't want to have to get into roll cages and frame stiffening. Maybe someone has done one of these swaps before and can shed some light on this?

 

[565bbchevy]

The big block swap itself is not all that hard but it depends on the purpose of your build since
to make a 427 have 600 horsepower would make for a very unstreetable engine, do you have any of the engine specs for it?

 

[MrSony]

There are companies that make frame braces, and seat braces (behind the rear seats, can see from the inside of the trunk). And if you have a 200r4, do consider having it built up or dropping about 1600-1700 for a beefy one. Although a 700r4 would probably last better and longer behind a 600hp big block that prolly has 600+lbft. Very good transmissions. Also either look for an 8.5 out of a GN or 442 (GN has 3.42 gears 442 has 3.73), or find a ford 9 inch or ford 8.8 and put it in there. Brackets will need to be made of course.

 

[Garrett1982]

There are companies that make frame braces, and seat braces (behind the rear seats, can see from the inside of the trunk). And if you have a 200r4, do consider having it built up or dropping about 1600-1700 for a beefy one. Although a 700r4 would probably last better and longer behind a 600hp big block that prolly has 600+lbft. Very good transmissions. Also either look for an 8.5 out of a GN or 442 (GN has 3.42 gears 442 has 3.73), or find a ford 9 inch or ford 8.8 and put it in there. Brackets will need to be made of course.

A 4L80e would be better behind a bbc than a 700r4,especially in that power range. The low first gear wouldn't be neccessary with the torque of a big block, and the 4L80e being based on a th400 would make it a natural fit. I have never heard anything good about a 700r4 or the 4l60e.

 

[pontiacgp]

with 600 hp I'd be taking the body off, boxing the frame, upgrading all the factory welds and adding braces....then upgrade the suspension and brakes

 

[MrSony]

A 4L80e would be better behind a bbc than a 700r4,especially in that power range. The low first gear wouldn't be neccessary with the torque of a big block, and the 4L80e being based on a th400 would make it a natural fit. I have never heard anything good about a 700r4 or the 4l60e.

I guess I should have worded it a bit better. They CAN be good transmissions. I know plenty of people that have un 700r4s on anything from 396s up to 502s. But yes, straight out the box a 4l80(e) are better suited. Although the "E"s need the computer.

 

[pontiacgp]

I guess I should have worded it a bit better. They CAN be good transmissions. I know plenty of people that have un 700r4s on anything from 396s up to 502s. But yes, straight out the box a 4l80(e) are better suited. Although the "E"s need the computer.

you can build a 200 r4 to handle the same power the 700 r4 can and the gearing on the 200 r4 is alot better

 

[MrSony]

you can build a 200 r4 to handle the same power the 700 r4 and the gearing on the 200 r4 is alot better

Yeah. By far. From what I remember the drop from 1-2 in the 200r4 isn't as drastic as the 700r4. That's why it was happy behind the turbo buick.

 

[pontiacgp]

the 1st gear in a 700 r4 is a granny gear in my opinion. I think GM first intended the 700 r4 for truck applications and it came as an after thought to put them in cars.

 

[MrSony]

the 1st gear in a 700 r4 is a granny gear in my opinion. I think GM first intended the 700 r4 for truck applications and it came as an after thought to put them in cars.

Yep. I remember them going out CONSTANTLY in the C/K1500 trucks within a year of light use. My stepdad's '91 had at least two of them and one rebuilt twice.