BBC swap into SBC 68 Impala - Chevy Impala Forums
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post #1 of (permalink) Old 04-08-2018 Thread Starter
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BBC swap into SBC 68 Impala

I am researching an engine swap for my 68 Impala SS. It's got the 327 with a TH400 and 12 bolt rear end. I am leaning towards a BBC, but I've read that there are a couple of different engine mounts. I had thought that I could order the mounts and oil pan for a 396 or 427 and just drop it in as the BBC was available in 68.

Am I over simplifying it? I've found threads on earlier and later years where guys are discussing this, but didn't find anything specific to this year. My apologies if I missed it.

I was thinking of going with a 383 to make the swap easier, but in keeping with the idea "There's no replacement for displacement", and the fact that guys are swapping out BBC for LS I thought Id go right to the Rat.
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post #2 of (permalink) Old 04-09-2018
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what are your hp intentions with the car? what do you want to do with it? the swap is pretty straight forward imho its been done for years time and time again. simple is the best way to go about it. i always go by SAE... simple and effective.
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post #3 of (permalink) Old 04-09-2018
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If it is a show car I might consider a BBC, or if looking to run deep into the single digits in the quarter mile. Otherwise it is too much weight for little if any payback.

For a street car I would do a LS variant with an overdrive transmission. NOT a true LS1 or LS6 huge price premium on those

Knowledge is a great replacement for displacement. I have mopped up cars with bigger much more expensive engines in trailered cars with my true street car that had thoughtfully selected quality parts vs. just the ones that sounded good.

A 6.0l LS truck engine with decent heads/cam and a 4L60E in a true street car will run fast enough at the strip to need a rollbar( 11.5). Overdrive transmission will get you a deeper first gear and overdrive plus lockup so you can run a decent higher stall converter, and likely be friendlier to drive than what you have now. Even a few mods on a 5.3l like headers and tune will have it performing better and driving better than what you have.

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post #4 of (permalink) Old 04-10-2018 Thread Starter
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I'm after a nice street motor with low end grunt. Somewhere between 400 and 500hp, enough to have fun but not to expensive to build. I am considering the LS, but think the BBC will look right in the car. I'm pricing out the options, and to be honest I was surprised how much a 383 was going to be. With the LS the parts to get it into the car add up quickly, and with the LS being so popular they sell pretty quick and the prices are climbing.

No doubt the BBC will be heavy, but they do make alot of torque and the car is not likely to win any autocrosses any time soon. Also the car isn't going to be a daily, so for simplicity regardless of what I do for a motor I intend to keep the TH400 and 12bolt, when funds allow I plan to go with a gear vendors.

If I do an LS I plan on swapping out the EFI because I don't want to mess with computers, for my fun car I plan on sticking with the KISS principle. I'm planning on taking the car out to shot some pics so I'll post something soon.

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post #5 of (permalink) Old 04-11-2018
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Quote:
Originally Posted by Dwayne J View Post
If it is a show car I might consider a BBC, or if looking to run deep into the single digits in the quarter mile. Otherwise it is too much weight for little if any payback.

For a street car I would do a LS variant with an overdrive transmission. NOT a true LS1 or LS6 huge price premium on those

Knowledge is a great replacement for displacement. I have mopped up cars with bigger much more expensive engines in trailered cars with my true street car that had thoughtfully selected quality parts vs. just the ones that sounded good.

A 6.0l LS truck engine with decent heads/cam and a 4L60E in a true street car will run fast enough at the strip to need a rollbar( 11.5). Overdrive transmission will get you a deeper first gear and overdrive plus lockup so you can run a decent higher stall converter, and likely be friendlier to drive than what you have now. Even a few mods on a 5.3l like headers and tune will have it performing better and driving better than what you have.
i second this completely!!

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Originally Posted by Templar View Post
I'm after a nice street motor with low end grunt. Somewhere between 400 and 500hp, enough to have fun but not to expensive to build. I am considering the LS, but think the BBC will look right in the car. I'm pricing out the options, and to be honest I was surprised how much a 383 was going to be. With the LS the parts to get it into the car add up quickly, and with the LS being so popular they sell pretty quick and the prices are climbing.

No doubt the BBC will be heavy, but they do make alot of torque and the car is not likely to win any autocrosses any time soon. Also the car isn't going to be a daily, so for simplicity regardless of what I do for a motor I intend to keep the TH400 and 12bolt, when funds allow I plan to go with a gear vendors.

If I do an LS I plan on swapping out the EFI because I don't want to mess with computers, for my fun car I plan on sticking with the KISS principle. I'm planning on taking the car out to shot some pics so I'll post something soon.

Templa
templa honestly the ls isnt expensive to built specially at the 400-500 hp level. we just finished up my brothers mustang with a 5.3 swap that the entire swap was cheaper to do than rebuilt a 4.6 5.0 mod motor. now with that said. we put a big cam in it.

We installed a cam, dual valve springs, new lifters (stock heads) mls head gaskets new head bolts a set of headers with all stock truck accessories. th400 and stock 8.8 diff. still finishing up the tune. but so far it made 455 to the tire at 5200 rpm and its still not done... it will easily make 510-525ish when its finished

my car setup is looking to push 800 on a stock bottom end 4.8
it was physically cheaper to swap the ls put the turbo on with the fabrication and parts for the turbo and the turbo itself, harnesses, bigger injectors, throttle body, cam, valve springs, trunnion kit, pushrods, arp head bolts, etc.. then it was to have a 355 built to make 700+ hp. i have around 5k if that!! In the entire setup including the cost of the engine.

For me the ls was a no brain'er just based on ease of donor engines/junk yard parts avail.
PLUS
Machine shops around here wanted 35-$4500 just to build a 355-383 or even a 400 sbc short block.. then you need another $1500 in cylinder heads. not including price for rockers, valve train, cam, all the tin, intake, carb... your talking close to $10k and it isn't even fired up yet.

my advise to you is don't look at is a band wagon ls way... look at is as the SAE way.. you chose the ls because "this this and this".. not because everyone else did it..
That's how i look at it...

You can even dress the ls engine up to make it use old school sbc valve covers. An Holley makes an efi system that is self learning even runs the fans and ac .. it completely doable

But best of luck to you in what ever you choose. Did you ever get some pic's of the car by chance?
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1977 impala Aero Coupe White
Turbo LS/TH400 Disc Brake Conv.
1977 Impala Aero Coupe Red
Bone Stock 305 2bbl on Studded snow tires
1978 Malibu Landau coupe
"Mini-Me"
2015 F250 Platinum CCSB

Last edited by Stockcar10; 04-11-2018 at 11:55 AM.
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post #6 of (permalink) Old 04-14-2018
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A 383 does NOT add any meaningful power unless the topend is upgraded. The heads and cam are where power is made, and a larger displacement under them can support airflow from the heads and cam but does not make power in and of itself the way people think it does, and a well done 383 does cost money, heck even a poorly done one is expensive.
$3500-4500 383 shortblock might add 10-20hp if you are lucky, the same amount spent on good heads/cam/valvetrain/intake could add 100hp if the shortblock is capable of handling it and it will likely take some more rpm.

This is what I did with my 96 Caprice I spent $3500 on good heads and cam, and same track same day having driven to the track could beat cars that had more than twice as much spent on a 383 and rolled off a trailer.

4-500hp is so simple these days you can get there any which way. A crate BBC might be a good option for you as they are often reasonably priced compared to finding a junkyard one and having it gone thru and better quality than most local shops are capable of. With the crap first gear of the TH400 the lowend torque will be appreciated.

Been a LONG time since the 454 was available in any numbers, might be hard to find in usable condition. You might find that the 502HO at $7000 is a good deal and that motor is very valvetrain limited, just upgraded valvesprings will add meaningful power. Friend has one in a '68 Camaro and had a shop look it over before modifying and it is VERY well built, the JE forged pistons were matched within 2grams
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post #7 of (permalink) Old 04-21-2018 Thread Starter
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Thanks for the info. The potential of the LS is great, and the power with less weight is very attractive. But it's tough to beat a BBC for low end torque, and with a BBC I could keep my current gears because of all that low end torque. I suppose at the end of the day it will depend on what I come across first at a price I can live with. Maybe it's my age, but I'm leaning towards the BBC
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post #8 of (permalink) Old 04-22-2018
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Hopefully you can find one in usable shape. If not like I said look at the GM crate options they are well built and competitively priced.

If you did an LS and used the modern tranny that will help a fair bit on the gearing.
TH400 is 2.48 first
4L60E 3.06
6L80E 4.02 but you would rarely ever get to use 6th

I totally get the torque thing, my current daily is 440tq from 0-43mph. Electric torque is amazing, buyin for anything fun to drive or with range is steep though.
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post #9 of (permalink) Old 12-13-2018
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Hey, new to this forum. Just picked up a 68 2 door sport coupe impala. I have a 454 already built for roughly 450hp paired with a Th400 ready to go from a trade I did. I m trying to find either an existing thread about swapping a BBC into a 68, or just info on what I need. I tried searching with the forums search feature but this is the only BBC 68 swap thread.

I saw something in a google search about new engine to frame mounts. As well as suspention spring swap. Can anyone shed some light on these topics. Specifically some part numbers to look into for engine mounts for the swap. Impala currently has a slightly built 307 SBC.

If this was covered on this forum or another forum, I would approciate links if possible to go read them through. Thanks!
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post #10 of (permalink) Old 12-13-2018
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Originally Posted by Djeepmyers View Post
Hey, new to this forum. Just picked up a 68 2 door sport coupe impala. I have a 454 already built for roughly 450hp paired with a Th400 ready to go from a trade I did. I m trying to find either an existing thread about swapping a BBC into a 68, or just info on what I need. I tried searching with the forums search feature but this is the only BBC 68 swap thread.

I saw something in a google search about new engine to frame mounts. As well as suspention spring swap. Can anyone shed some light on these topics. Specifically some part numbers to look into for engine mounts for the swap. Impala currently has a slightly built 307 SBC.

If this was covered on this forum or another forum, I would approciate links if possible to go read them through. Thanks!
I just looked on Rockauto. They show parts for 68 Impalas. There was no 454 option, but I selected the 427, and could see motor mounts and front springs for that car/motor combination. (That motor should use the same mounts and springs as the 454, right?)

Often, you can get the OEM p/n from the listing which in turn you can search elsewhere for better price or availability. (Altho, Rockauto is hard to beat!) Also, when you drill down on a particular part, you can sometimes pick up additional alternative part numbers.

So, if they don't have what you want, you might at least get some info that you can use elsewhere.

HTH.

Doug

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post #11 of (permalink) Old 12-14-2018
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Thanks Doug! I ll check out Rock auto for some part numbers!
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Also consider things like accessory drives, and exhaust. I have a BB in a 70 and am having one hell of a time getting headers to fit. The stock manifolds were warped, and I decided I would step up to headers in preparation of a 496 build in a couple years. I'm not having luck with the exhaust so far.
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