400 SBC or 454

[jobberone]

My 76 Cheyenne long bed 4x4 is at the painters.

It's supposed to have a 400 SB but it came with a 350. How do I see if it's a 400? It has an aftermarket intake and a small Demon on it now with supposedly a small tow cam. The engine is borderline needing a rebuild starting to smoke some.

I have a 454 I built a few years ago and I never put it in the truck. 60 over with stock bottom end 2 bolt cast crank. 702 heads with big valves, valves unshrouded, .565 hyd cam, air gap intake, and I have a 750 Edelbrock single pumper, and a Speed Demon 850 elec choke for it. I'm guessing 400+ honest HP and 500 torque but what do you guys think? Is it too much for the truck even though I'm not much of a hot rodder anymore?

Would you put the 454 in the truck? Would I have to change the front suspension and if so how much to do? If the 454 then which carb and what rockers would you use. I had some 1.65 rollers but I'm thinking just good 1.7s in this truck with at most 5800 rev limit. Not sure 1.8s would work and whether that is a good idea anyway.

It has a 350 stock tranny although I've been told it was a 400. Don't they have a different pan?

I'm also going to put some 15x10s with 31 or 32 tires or 16". My kids say 18+. I don't think big wheels are a good idea but what do you guys think?

Great forum!

[884x4Sub]

if you go to a BB all the ps,alt, a/c etc brackets can be a hassle.....

[Tony@AirRideTech]

If you dont have the block numbers to run the balancer is your give away. The 400 are internally balanced motors and the 350 are external. The 400 balancer will have an odd chunk missing from it.

if it were me... and the 350 is running bad, I would take that big block, slap that 750 on it and call it a day. your 850 is too much fuel for what you have put together there.

[454HO]

Originally Posted by Tony@AirRideTech

if it were me... and the 350 is running bad, I would take that big block, slap that 750 on it and call it a day.

X2

Sounds like a 'no brainer' to me.

Oh yeah, welcome to the board.

[jobberone]

Originally Posted by 884x4Sub

if you go to a BB all the ps,alt, a/c etc brackets can be a hassle.....

See I hadn't even thought about that. And the motor mounts. Would they be a problem, too? I think the radiator is big enough.

Originally Posted by Tony@AirRideTech

If you dont have the block numbers to run the balancer is your give away. The 400 are internally balanced motors and the 350 are external. The 400 balancer will have an odd chunk missing from it.

if it were me... and the 350 is running bad, I would take that big block, slap that 750 on it and call it a day. your 850 is too much fuel for what you have put together there.

Great stuff. I bought the 750 Edelbrock for it thinking it would give me about 95+% fuel/air efficiency. I got flamed elsewhere for the whole motor. Said the bottom wasn't good enough for the rest and the carb was going to lean me out. I didn't think I was that far off with it. I think I can use the Demon on a built 440 though. If not then off to eBay.

Is the engine heavy enough to change suspension? Chevy supposedly put a different suspension under the 454. Is that correct? That sucker is heavy.

[Tony@AirRideTech]

realistically it is only a couple hundred pounds heavier than a small block... if it sags, slap an add a leaf in it.

[shrtbx]

There might be others here that have different opinions but i would keep the 400 sbc. Seems to me like you would have to make some adjustments up front for the weight of the 454. I put a 400 sbc in my 81 el camino and man does it go. Its bored .030 over with edlebrock cam and manifold combo stock heads. The only thing you have to really worry about with the 400 thickness of the block it has a siamese style set up and any sort of crack can cause problems. Also make sure you get heads (if you are getting a new set) that are for a 400 sbc or have the extra steam holes drilled into them.
Also make sure you have more than enough cooling for it. They tend to run hot at times.

[trixter99]

I say go with the big block if you have it but be prepared for some serious fuel comsumption. And as far as the wheels go I would go with 18"s and a 33" tire just because they look cool and handle WAY better because there is less sidewall to slop around on.

[jobberone]

Originally Posted by Tony@AirRideTech

realistically it is only a couple hundred pounds heavier than a small block... if it sags, slap an add a leaf in it.

Ok. Looked those up. I'm embarrassed to say I don't remember it having front springs. It's at the painter.

Originally Posted by shrtbx

There might be others here that have different opinions but i would keep the 400 sbc. Seems to me like you would have to make some adjustments up front for the weight of the 454. I put a 400 sbc in my 81 el camino and man does it go. Its bored .030 over with edlebrock cam and manifold combo stock heads. The only thing you have to really worry about with the 400 thickness of the block it has a siamese style set up and any sort of crack can cause problems. Also make sure you get heads (if you are getting a new set) that are for a 400 sbc or have the extra steam holes drilled into them.
Also make sure you have more than enough cooling for it. They tend to run hot at times.

I was thinking of selling the SB and using the BB. But I know my gas mileage will plummet from 15+ to 10+. So I got the think about it.

Originally Posted by trixter99

I say go with the big block if you have it but be prepared for some serious fuel comsumption. And as far as the wheels go I would go with 18"s and a 33" tire just because they look cool and handle WAY better because there is less sidewall to slop around on.

I hadn't thought about the sidewalls at all. Does it make that much difference. I'm not looking for performance out of the truck but I'll never say I don't enjoy the feeling. I need to look at the price of tires. I'm either going to powdercoat the wheels on it, refinish them or swap out. Tires I'm not sure about.

[87Lowrider]

Welcome!!

I just finished converting my '87 from a sbc truck to a bbc with the 454 backed by a TH400. Mine is not a daily driver so I went all out on a few things,ie; brackets, radiator, accessories, etc

If yours is a DD, you may opt for the sbc for economy. Mine could be a DD since my office is less than a mile from home. It's pretty close to the specs of yours. Oh, and listen to your kids sometimes... I just put 20s on and they turned out pretty well.

Heres the thread I ran for the build
http://67-72chevytrucks.com/vboard/s...d.php?t=279281

Good Luck!


Kenny

[Dooley]

More info on smallblock 400 here. Never had problems with the many I've owned.
http://67-72chevytrucks.com/vboard/s...d.php?t=297802



Only the 400 small block and 454 BB are externally balanced.

[Hoods69BadBowTie]

I say if its a 350 run the BB. If its going to be a DD you may want to keep the SB. If its a 400 SB you can still have a ballsy motor and get a little bit better gas mileage then the BB. I do like those BB valve covers though.

[jobberone]

Originally Posted by 87Lowrider

Welcome!!

I just finished converting my '87 from a sbc truck to a bbc with the 454 backed by a TH400. Mine is not a daily driver so I went all out on a few things,ie; brackets, radiator, accessories, etc

If yours is a DD, you may opt for the sbc for economy. Mine could be a DD since my office is less than a mile from home. It's pretty close to the specs of yours. Oh, and listen to your kids sometimes... I just put 20s on and they turned out pretty well.

Heres the thread I ran for the build
http://67-72chevytrucks.com/vboard/s...d.php?t=279281

Good Luck!


Kenny

Wow. Nice truck. Can't believe how close our basic setup is. Same carb and intake. Same bottom end. I don't know those heads. The 702s may be a bit much for my use esp with the big valves but it won't be too much I think. You got me thinking radiatior and I'll have to really work to get the engine compartment looking as good.

I got the fever now. I think I've got some headers for the BB. I'll try and keep you guys up to date once I start with it.

Thanks for all the posts and advice. I will look at some 18s and up but I think I'll stay with the 16" M/T Classic IIs and some 31 to 33" tires.

Thanks again all.

[jobberone]

Originally Posted by Hoods69BadBowTie

I say if its a 350 run the BB. If its going to be a DD you may want to keep the SB. If its a 400 SB you can still have a ballsy motor and get a little bit better gas mileage then the BB. I do like those BB valve covers though.

I'm a little gassed about the BB swap but it wouldn't take a lot to make that SB kick butt. I've even got a L79 I could put in it. I'd just never be able to use pump gas.

I had a 65 El Camino and I was going to put that in it but I changed my mind when I got a 67 Chevelle.