Rockin' the 250 inline 6 right now, but the plan is to put in the big 454. Go big or go home. It was rumored around that I would need to replace the subframe to support it, can someone confirm this? Also, if this has already been discussed, my apologies. I checked a few pages, saw nothing related to this.

 

your going to have to do some major reinforcing with the bb, that torque can cause some damage.

 

Im not sure that there was a different subframe for a six cylinder. My car started life with something small lm sure and my 572 sits on top of the stock subframe real nice!

 

^^^ What he said^^^

I have no idea where your rumor came from. The subframe on our cars is the same from I-6 to 427 to 455 in the early Trans Ams. All the same. No reinforcing either. The factory did add a brace later (79ish) from the lower control arm mount to frame rail. These get in the way of header installs on small block cars and get tossed without any effct on the car. I would how ever install sub frame connectors regardless if you left the I6 in it or not. That and solid body bushings, but that can be argued till the sun comes up.

Lets remember these cars got sent out of the dealerships with as 427. Vals car comes to mind as well as Baldwin Motion cars. Like i said the Trans Am sub frame is the exact same as Camaro. Those came with 455's until like '77 or something. So its not like its uncommon.

 

Alright, thanks guys, going to save me a little money and a LOT of time!

 

IMO I would probably replace my front springs, I love and I mean love those Chevy Big Blocks. That there is the sound of victory.

 

Alright thanks for the heads up, I love them too, I just need to get the right cam to get that barely-running sound. Love it!

 

I have not checked into the Thump-er cam very much, I don't know about the performance of this cam but the sound is right. Maybe a cam guru will come along and enlighten us both. Good luck with this project.

 

The springs for an I6 are probably equal to, or heavier than those for a SBC. I ran SBC springs for years inmy '71 to get weight transfer on launch, and when I completely rebuilt my front suspension I replaced the coils with new SBC coils. It still sits great, and no issues with my BBC.
I think most the morons who make up these myths about subframes needing to be changed, (or other rumors) have never owned a BBC powered 2nd gen Camaro. Another myth I hear is the tranny needs to be moved back, or the rearend is different for a I6 or a SBC vs. the BBC. Both are false, and the only year 2nd gen that had a different rearend was 1970, when they still offered a 12 bolt rear for the Camaro.
Damon's reccommendation of subframe connectors is a must! If you run for long without them you'll see the result of body panel misalignment. I had lots of trouble with mine when I began bodywork trying to get things lined up.
The Thumpr cams have a great sound, but they wont just give you more power if the rest the engine isn't built to match up with that cam. Any cam requires it be matched as a complete package of CR, heads, intake/carb, and exhaust. Just dropping a cam into an engine usually ends up sounding nice, but performance suffers. I think there are better choices for performance, and some sound as good. You just need to decide what the rest of the engine will be prior to choosing any cam. I personally like high lift cams, with short duration, and LSA around 110 for the street BBC. I also like a streetable CR of around 9.5:1-10:1 for today's gas.

 

Really appreciate the in-depth reply. I'll begin research on "subframe connectors" because I'm not entirely sure what that means, as I am just getting into cars and such. And the info about cams is very helpful, I will make sure to get everything else done first, I suppose. I have a lot to think about! Luckily I have a buddy or two that can help me out with the cam, but any suggestions I can bring to him are great.