Big block or small block?

[Ugly78Cutty]

Just joined the site after reading a ton of posts but I'm still torn.. I bought someone's disaster for next to nothing pretty much for the price of the heads that are on it and they are nothing special. It's a 78 cutlass that has a 350 in it with flat tops and 76cc protopline torkers with the 2.02 valves so not enough compression to do anything with. The headers are fine other that whoever built it cut the collector flange off and welded it straight to what looks like 1.75" dual exhaust with glasspacks....that's coming off too...
So I'm not sure what I want to do. I want it to run mid 12s.... With the sb I'm gonna be starting from scratch. So if that's the case, I have an opportunity to buy a motorhome 454 with 40k on it and lets just say for arguments sake I have the transmission (th400 with whatever converter prob a 3k) and the rearend (bolt in 9in on the way) covered.
I'm thinking it would take less to get that 454 to run the numbers I want than a sb. prob be cheaper too if I have to start from scratch with the sb. A 383 would do it but for the money I could have that 454 in the car even paying retail for the hookers. Anyways I just wanted to hear any thoughts any of you have on my project.
Thanks

 

[Kwik_Cutty88]

You can definitely run 12's with a small block. You're going to be adding a ton of weight with an all iron big block. I don't really think that a motor home 454 is going to make much for power, but It should make a lot of torque. I think they set those motors up to make their peak power at really low RPM's to get the motorhomes moving. At the least you'd probably be doing a refresh on the motorhome engine (i.e. re-gasket, check the bottom end and cylinder walls) before dropping it in right? And that's assuming that the 454 is healthy. Also you have to think about the fact that no G-Body came with a big block from the factory, so some modifications will have to be done. There are plenty of people on here that run big blocks, so I'm sure they could give you more information.

 

[565bbchevy]

Now I am definitely a BBC guy but the only way I would go with the 454 is if I was putting some aluminum heads on it, I have built quite a few BBC Gbody's and two with iron heads and no matter what you do it always feels front end heavy.
Considering the 454's application is a motorhome and not knowing what year it is it could have those crappy peanut port heads that barely flow enough for a low rpm application.

 

[MrSony]

I'd just go with a standard 383 or 388 stroker. aluminum top end, roller valvetrain. Lower the ccs in the heads for more compression and true dual exhaust with headers. Works magic.

 

[Ugly78Cutty]

If I do the big block it will be my first chevy bb. Ive done many big block darts from mid 12s with junkyard parts to being part of a 9.50 car. The 454 I'm talking about runs fine and I'm gonna pull the valve covers off next weekend and see where I'm at. If they are crap heads Ill put some closed chamber oval ports which Ive already found and step up the cam and intake a bit. I'm grabbing another 4bolt 454 block to use if I end up building something more substantial.This is just gonna be a stripped down toy, if it makes it to the strip twice a yr Ill be amazed. I don't have enough time anymore to keep up on much more than I'm trying to build now or Id be putting something together a whole lot faster than a 12.50 car. Thanks for all the info.

 

[-83MONTESS-]

The big block doesn't weigh much more than a small block. My car doesn't feel front heavy at all. Maybe because I have good aftermarket suspension parts.

To answer your question-I swapped my small block for a big block and I haven't looked back. The engine you have a chance on getting won't be a burner but it will pull trees down. Some better pistons, decent factory 049 or 781 heads and a mild cam and it will be a totally different beast that I assure will not disappoint you.

The cost to build a big block isn't much different either. I have $5,500 in my roller cam 496 stroker with EFI total. That includes buying a lot of stuff that I swapped out for other stuff later on.

 

[-83MONTESS-]

I forgot to add the swap part. Same engine mounts as a small block, 68-72 A body headers fit and are wayyyyy cheaper than the swap headers, I have no issue with oil pan clearance with my 7qt kick out pan, I can reach every bell housing bolt from the top (no HVAC box), and I never had radiator or brake booster clearance issues.

 

[Ugly78Cutty]

I forgot to add the swap part. Same engine mounts as a small block, 68-72 A body headers fit and are wayyyyy cheaper than the swap headers, I have no issue with oil pan clearance with my 7qt kick out pan, I can reach every bell housing bolt from the top (no HVAC box), and I never had radiator or brake booster clearance issues.

Did those Abody headers goes right in? I was doing some research and read that some worked better than others. My HVAC box is coming out too, that thing is ridiculous, if I need defrost I can build something that has nothing under the hood I'm sure. I'm working my way forward from the back of the car so I have a minute to make up my mind (9in should be here in the next day or two). Either will get me there I just have to make up my mind. Thanks.

 

[-83MONTESS-]

Did those Abody headers goes right in? I was doing some research and read that some worked better than others. My HVAC box is coming out too, that thing is ridiculous, if I need defrost I can build something that has nothing under the hood I'm sure. I'm working my way forward from the back of the car so I have a minute to make up my mind (9in should be here in the next day or two). Either will get me there I just have to make up my mind. Thanks.

For the headers I had to move the brake proportioning valve back on the frame an inch or so. It was a little close to the headers for me but all in all was probably fine.

I used 12 ARP head bolts so I had to grind the bottom of the header flange a little to clear. I have had to do that with every header I have ever used though.

I also cut a little off the passenger side lower control arm mounts because they hit a little.

To install I lifted the engine a little bit and slid them right down from the top. A much easier install than my swap headers. And it was easy to get to every spark plug. I used the painted Hooker 2455 full length 2' primary 3.5" collector headers. Other guys have used other A body models and some have even used 1st gen F body headers. My swap headers are nice but don't seem to fit much better. The only reason I did the swap was because the engine was out and I found them very cheap locally. Hopefully the slip tubes won't leak.....something you don't have to worry about with the 2455's.

 

[gbodytoys]

I say LS, but otherwise, big block with EFI. I'm happy with my 383 sb, but a big block just really looks good in that big engine bay.