SB vs BB

by driveit Fri Jun 21, 2013 10:38 am

I have a chance at getting a 454 out of a mid 80s pickup. My questions is SB or BB! What is your opinion and why? Which one would get better mileage stock 74 SB with headers weiand intake Edelbrock 650 and HEI supercoil or completely stock 454 with 650 Edelbrock carb?

by Psychlonic Fri Jun 21, 2013 10:51 am

Big block is cheaper power with a higher ceiling, but a small block is more weight efficient if you're going for more of a pro touring build. I'd say in your question the small block would still get better mileage.

by driveit Fri Jun 21, 2013 11:00 am

Thanks Psychlonic.

Keep em coming guys!

by dynchel Fri Jun 21, 2013 11:16 am

The main reason I never seriously considered a big block is that none of the performance stuff from the small block can be retained (except the distributor, and the carb, with some work). I all ready have headers, intake, a built th350 (you might need a turbo 400) reworked heads etc.

by driveit Fri Jun 21, 2013 11:24 am

Got a TH350 currently that leaks somewhere! Hoping to find an overdrive or manual somewhere soon!

by Bruisr Fri Jun 21, 2013 2:11 pm

I run a Th350 behind my 454. Have never had a TH400. I love it and will never go SBC, if I can. If you have the BB from the truck then you have all that is needed. Hek, mine came out of a jet boat. I'll get into more details in a bit.

by driveit Fri Jun 21, 2013 3:29 pm

Please do!

by Bruisr Fri Jun 21, 2013 8:54 pm

I'm back! I had a perfectly good running 350 (Big cam, worked heads), when My bro-n-law gave me a 19' ft. jet boat. I took the 454 from it and gave the rest away. It was a stock 454 with 353049 heads. I had the heads ported and polished, a .540 lift cam, Eddy Victor Jr. with a Proform race 750 cfm. I had my Th350 previously rebuilt before this so I left it alone. I was running a 4.10 gear with 3000 stall and 29 in. tall tires. Sadly I was taken to the cleaners by the shop that installed my rear gears, It wasn't until I blew it up that I realized they installed a Gov-lock limited slip. It was so bad I couldn't even get the axles out of the housing! I pieced together the parts needed for the alternator, and pwr. steering brackets. (I have an extra SET). I mistakenly used the 350 clamshell motor mounts, (works just fine). I got greedy and wanted more cam so I removed it to install a bigger one, the cam didn't set right and ate up a lifter and put metal into the oil which got into the bearings, and spun a rod bearing. Out came the 454 and the car sits. Fast Forward to now, Got the 454 rebuilt, just waiting to assemble, the install into my 73 elco. As far as fuel economy goes, who cares! I was in it for fun and I miss it. New engine will be the same just with a little smaller cam, Still trying to decide on one, but I'm looking for around .540-.575 lift. My recommendation! If your after fuel economy keep the SB BBC's are thirsty and proud of it. The All iron 454 weighs around 110 lbs. more than an all iron 350. I'm a firm believer of more cubes=more power, but it costs a little more. For me, opening the hood and seeing all that motor, is intimidating. I could go on....

by Bruisr Fri Jun 21, 2013 9:07 pm

I can't say which engine is better. That all depends on the end user and his/her style. I fell in love with BBC and saw an opportunity for it so I ran with it. My father has a built 383 in his 66 chevelle and he loves it. He claims its more expensive to build a BB than a SB. I say it depends on what you are tying to build, I personally feel the BB will yield more power and not spin as fast to get it, BUT, that's my opinion and I'm no expert. For me its a preference, nothing more, nothing less! I like big engines, big tires, and big cars!

by ant7377 Fri Jun 21, 2013 11:46 pm

Big Block no question,if you have it use it. You will be way ahead in the long run.

by pila Sat Jun 22, 2013 7:00 am

The big block Chevy is one of the few engines I have never had or worked with. Great engines from what I do know.
Kinda interesting that many good big block builds will peg a 1000 HP dyno with no problem. Very Happy

It the old days I fooled with Hemi Chryslers, Pontiacs and Cadillacs etc, and a lot of small block Chevys, but just didn't get around to a BBC.
The TH350 transmission will survive better with the right shift kit, regardless of the engine it's bolted to. A Transgo shift kit for example, applies more pressure to clutch pistons of course, reducing the slippage and clutch wear during shifts.

by LSANTI76 Sun Jun 23, 2013 2:56 pm

If you are concerned with MPGs & city driving I would go SB. If you are driving highway miles & you could go BB & change to a steeper rear end ratio to keep cruise RPMs down & still have plenty of power for those non MPG concerned spirited driving moments. BB & city MPG don't mix well even with a light foot & gearing. If you were to go BB keep in mind you may want to put stiffer springs & larger sway bar to retain the same or improve handling characteristics / ride height from the extra front end weight. I went through this same decision 15 yrs ago after retiring mine from 5 yrs of daily commuting. I then went from SB to BB. Also remember you will need to change out your pulleys / brackets & larger radiator. As already mentioned...a finely built TH350 w/cooler & TransGo Kit will survive behind a 450 horse BB.

by 1973 454 MONTE Sun Jun 23, 2013 8:54 pm

i bough mine with an original 454 in it. i cant see myself ever putting a 350 in it.

mine did come with a 400 trans also,but did not chirp going into second like my 350 trans did.

so i have a 454 with a 350 trans,that work good together.

by alleyball4 Sun Jun 23, 2013 11:25 pm

I have a small block in my 73 SS .... but if you want to get attention at a car show, for example ... roll up in a "big block" ... there's nothing better than the rumble of a tuned-up big block.

If you're after mileage, or daily driving, then the small block is probably the way to go. There are alot of variables, though on gas mileage, such as:

1. rear end gear. A 2.73 or a 3.08 is going to get you better gas mileage than a 3.73 or 4.11. You're going to give up alot in torque, etc, though.

2. transmission. The 350 turbo or the 400 turbo might not always give you the best gas mileage. That is the appeal of people switching over to transmissions, such as a Muncie 4 speed, a Tremec 5 or 6 speed, or even a built 700r4. The extra overdrive can make a big difference in gas mileage, and is alot easier on your motor.

3. carburetor. for mileage bigger isn't better. This is where an engine builder's advice is worth it's weight in gold. You want to match the carburetor up with the cam, compression, etc. You don't want to go too big, or too small .... it can really screw your motor up.

If you're after strickly horsepower, and don't care about the prestige of owning a big block ... sometimes taking a small block, and stroking it to a 383, can get you more horsepower than a big block, and can be a little more economical. Remember, going over to a big block, you have to change out some of your front suspension, springs, etc.

It's all what you're after .... big block cars on average sell for more than small blocks, and definitely get the attention.

Hope that helps .... good luck

by driveit Tue Jun 25, 2013 8:58 am

Thanks everyone for all of the information. The idea of having a BB is definitely tugging at me. Always wanted one, but now that the Chevelle is turning into more of a driver than a hear and there tire burner I am leaning toward the SB. Even considering a fuel injection system of some type to see if I could get better mpg's through that as well.

by dragons_lair59 Thu Jun 27, 2013 12:19 am

It's a proven fact that with factory 3.08 gears a properly tuned BBC will get the same or better mileage because of both the torque the motor has and the fact that it don't have to work as hard to move the same amount of mass.

by 77mali Thu Jun 27, 2013 6:14 am

If I ever win megabucks, I would build a late 60's BBC like one (or all) of these:

375 hp 396 L78, 450 hp LS6 454 or 435 hp 427 L71.

Of course since I'm just a Plebe, my 350 hp 350 will have to do. I think I got around 12 mpg with my 77 Cutlass back in the day & $20-25 to fill the tank wasn't a total killer. Of course it had all the smog crap on it which if you remove you can prob get a well tuned old style GM 350 to approx 15-16 mpg even w a 4 valve carb.

by driveit Thu Jun 27, 2013 7:02 am

The debate continues!!!

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