foundvettelifeisgood

Other than acquiring a 427 motor, what's involved with transitioning from a 350? The car is a 4 speed. Please chime in.

RickyBerg

No problem whatsoever.

My car that left the factory as a 200hp smallblock car now hostes a 454 LS6 (replica) 470hp.

It still has the M20 gearbox and the 3,36 posi rearend from the smallblock.

I do some trackdays and clubracing and it works just fine.

What i DONT do is dragracing with sticky tyres!!

But occational tyre-frying with the street tyres have not caused me any problems during the years i have had the car.

AGVI

I believe pulleys and brackets are a different size as well as exhaust.

patraw03

I put a 350 in a 427 car and all it needed was new motor mounts.. The 4 speed should be fine for the project. I know by case is a bit different because I down graded, also the clearance for the hood may be off and you will probably need to use a low profile manifold.

cv67

Radiator too.


Other than that youll never own a 350 again unless its something stock for a DD after being spoiled by BBC power I can tell you that. Kick in the azz every time you drive it. Not much gear needed even with a cam, part throttle ahead of most cars out there. LOTS of fun.

garygnu

what year is your vette ?maybe consider a big CI sbc ,400 + CI.

oldalaskaman

or a 396 crank in a 454 block, poor mans 427?

donyue

Hi foundvettelifeisgood,

I had a hard time deciding between BBC, SBC, or LSX engine swap in my 1977. I decided to go with aftermarket SBC in order to keep as much of the original accessories as possible. If you swap in a BBC for a SBC then you will need pulleys, brackets, exhaust, front springs, and possibly a low profile intake would be required. There may also be other items that would be affected.

This link below is to the engine manufacturer that I picked for the 427 SBC DART SHP engine. I think it has all the pluses of a big block, (cubic inches, torque, horsepower, etc.) but also keeps the benefits of a small block (lighter weight, compatible accessories, etc.).

The LSX crate engine option is also a consideration but the higher cost of the engine swap kept me from going that direction.

http://www.tristarengines.com/perfor...tar-series.php

Any one of the engines will work, it is all a matter of how many additional changes you want to take on. I would say the SBC is easiest, followed by the BBC, and then finally the LSX.

Thanks

Don

7T1vette

I was going to post the above approach, but this advice says it all. Keep most of your engine compartment the same...just bore/stroke your block or buy a large displacement small block to get you where you are satisfied with the 'cubes'.

But, if you must have a LARGE engine up front, think about going really large....like 540. You can build a very tame 540, and it will still have a ton of torque.

BBCorv70

Depends upon whether you're trying to build a big block car as the factory did from 68 - 74 or simply want a bigger motor. I personally feel the factory didn't upgrade some parts for the big block packages without reason. It's more expensive for the manufacturer to design and stock two parts if one was truly suitable. To match a factory installation you'll need a new radiator support and radiator, 27 1/2" across. New fan shroud. The brackets and pulleys are all different. Different exhaust manifolds and pipes. Stronger front springs, caps instead of U bolts fastening the half shafts to the differential. Rear sway bar, bigger front sway bar. Different hood to give a bit more clearance.

The tach is different as well but won't make any difference in how it performs or holds up.

Others have successfully transplanted a big block without changing all parts mentioned above, a matter of preference.

John 65

I put a 454 in my 77 this summer. Being its incorrect, I wasnt about to use corvette only parts. So I made it ez and functional. Forget vette pulleys and brackets. I used a Chevelle set up for the alternator. Its on the right side along with a long water pump, and used a big block vette cradle for the ps pump where normally mounts for the bb vettes, it just needs to be built out about a 1/4 of an inch or so for belt alignment. I think its a thousand times better than the alt over the pump set up like stock, and a lot less $$$. I replaced the radiator with an aluminum one with 2 electric fans. Works great.

RickyBerg

Theres always a lot of theories about the weight when it comes to the choise between a bigblock or a smallblock..

My experience is that in real life this doesnt really matter that much as it may do in theory.
I know that when it comes to weight "less is always more" but on a street driven car i dont think it matters that much.

My example is my pal who is running a 377cui aluminiumblock smallblock with aluminium heads and manifold etc in his 66 C2, he also runs a 5-speed Richmond.
His whole setup is several kilos lighter than my 454 with steel block and steel heads.

Both engines are equal in horsepower, approx 470 in both.

Despite of the difference in weight we were running side by side (rolling start at 2nd gear) along the whole long straight (approx 600mtr long) during a day on the track.

I belive the biggest advantages of low weight will do best when it comes to dragracing launching and corner speeds.

As a reference i can tell that my bigblock C3 has a weight distribution of almost exactly 50-50 with half tank of petrol, no spare tyre and myself in the drivers seat.

Personally i think a BB looks wery nice in a C3 engine compartment.

rpoL98

i'm not sure how a BBC long water pump would work since the BB crank pulley is nestled very snugly into that recess designed into the cross member, possibly designed just for that purpose. if you run a LWP, then to get the crank pulley clearance you'd have to raise the motor higher, leading to other issues e.g. mechanical fan & shroud alignment, hood clearance. just IMHO that's all. mebbe with a single-groove pulley...? hmmm. or a small-diameter crank pulley which then under-drives the water pump, free's up horsepower.



i think the only BB intake manifold that has a chance of fitting under the stock-type low-profile hood might be the LS6 or similar pancake manifolds. i haven't tried that yet, but i see that Crane sells repop LS6 manifolds. otherwise you're looking at an L88 or other hi-rise hood and then you have all the air cleaner clearance in the world.

if you're just looking for the fan belt to drive just the alternator, it's a simple and reasonably cheap install. once you start doing BB C3 power steering, A/C, the C3 BB-specific brackets & pulleys add to the cost unless you can rig up GM BB short water pump brackets & pulleys from other chevy's, e.g. early chevelle, camaro, etc, before they went to the long WP. i think that was 1969.

Hedman, Hooker, etc and repop cast iron exhaust are no drama.

make sure all your radiator support seals are tip-top (to the hood, to the radiator). alum radiator and twin electric fans are good but the latter usually necessitates an alternator upgrade. 1970's BB's back-in-the-day did come with brass/copper radiators so alum might not be necessary.

i had upgraded my front springs to VB&P F41 coil springs while it still had a SBC in it, and when i dropped the BB into it, no change, at least non that i noticed, maybe it did, but i hadn't measured before/after. my SB had iron heads, stock radiator, whereas the BB had alum hds, and swapped to alum radiator.

one more thought, there's a reason C3 BB's had bolt-on diff yoke caps ("HD") instead of u-bolts.

that's my memory dump. I had at first swapped out my smogger 350 for a 454, but then got a clearance price on a 540 short block, and haven't looked back. However, not sure if the swap would be as rewarding with a 427 when as mentioned by others, modern technology has made large small blocks very feasible. the incremental reward isn't as great.

zuendler

When it comes to eye catching you will need a supercharged SB to beat a BB.
And you can put tons of money into a SB, maybe it will have more power than a BB, but people will always prefer the BB.
At the last car show i won a price for the "best engine" with my stock looking BB. There was another car with a SB, aluminium heads, dry sump oil system and many carbon parts and so on. Didn´t get half of the votes...

garygnu

you can put a 3 7/8 stroker crank in your 350 for 396 CI .I like the 3 7/8 crank over a 4" crank for a better rod ratio.competition products sells good priced short blocks and rotating parts.

John 65

Heres my set up. Has a drop base air cleaner on a Performer RPM manifold with a big fat Holley carb sitting on it and no need for any hood mods, it all fits under my stock 77 hood, which is a HUGE savings. Plus it looks 100% stock with the hood closed.

SuperBuickGuy

wow, what a clean install - looks better than factory

dang what a deal

buy this monster for your car
http://forums.corvetteforum.com/c3-p...num-heads.html

there is no chance you could rebuild a 454 for what he wants for this - even the compression would be a non-issue because the Corvette is so light....

alswagg

I was also contemplating swapping in a big block. However, I thought about going to a 454 Vortec MPI. I have one complete with the ECM. I was going to swap in the 383 MPI but it looks like the height of the 383 will be too high where the 454 vortec intake is much lower even with long air runners. Decisions, decisions. lol What to do this winter??? Al

John 65

Thank you ! Heres the other side. Trying to make under the hood very simple. Removed a lot of things that were not needed.

TheDucci

I am in the process of a BBC swap right now gathering parts for the swap out itself and a rebuild of the 454. There is a TON of information on this site for the swap. If you do some searches you will find a lot of information some say the front SBC springs and radiator work some have changed them out as well. As mentioned on this thread people have also used different pulley set ups but it takes some time and skill to make them work. I personally am going to run the BBC corvette pulleys and brackets as I know it works and it is one less thing to mess with. I also want to run an aluminum water pump and my stock fan and fan shroud as well. If you are going to rebuild the BBC yourself or have it done you should check out the Chevelles.com tech section in their forums as they have a lot of good information on motor combos and set up for all the different cubic inch big blocks.

This is as far as I am right now. I just got my block back from the machine shop, I have some pulleys and my brackets should be here this next week. I may have some spare pulleys by the time I am done?

Also depending on what year you are swapping into don't forget to check you bell housing size if you have a manual car as you will need the larger size for the 168T BBC flywheel.

Here are some links:

http://forums.corvetteforum.com/c3-t...-bb-build.html
http://forums.corvetteforum.com/c3-g...to-a-72-a.html
http://forums.corvetteforum.com/c3-t...ct-beater.html
http://forums.corvetteforum.com/c3-t...-for-days.html
http://forums.corvetteforum.com/c3-t...d-pullies.html
http://forums.corvetteforum.com/c3-t...-454-swap.html