Ram2180

My 69 was an original 427, now has a 350 that needs replacing. Want to put 427 back in. Should I go with big block or a small block 427. Not concerned about original status.

blue427

go with the bb,nothing else to say.

Mdbirk

No replacement for displacement...big block baby!!!!

C3 Stroker

If mine was an original big block, I would definitely put the big block back in. Car is set up for it, and easier to hot rod if you want more horsepower .

68hemi

And displacement is displacement. It doesn’t matter if it is in a small block package or not they will develop the same torque.

However for long term value I would try and find a date code 427 block for the car as it will likely make a difference down the road.

stingr69

There are no available small block heads that can flow as much as a big block head can so, go big block is my advice.

Ram2180

ok thanks for the feedback

Rescue Rogers

The big block is going to be a lot more expensive...but thats what I did and I love it.
YOu have to find all big block fan and accessory mounts and the only thing that will transfer from your engine is the carb and air cleaner, alternator and power steering pump if you have one. You will have to modify your exhaust down pipes if you arent running headers and if you are you may have to move the collectors and change your front springs to something stiffer.....again the big block is worth it

kossuth

Some suggestions. Know exactly what your plan is given just about everything will not cross over from the small block. The only items would be your carb and dizzy and POSSIBLY your accessories. If you are planning to fuel inject the motor either a Mark IV, Gen V, or Gen VI are all reasonably good choices are far as a block goes.

A 454 and a 427 are basically the same motor, just a shorter stroke. I would personally just stick a 454 in it and stick the 427 air cleaner on it. Only you and those very observant few (different balancer) would ever really know.

Know your possible donor vehicles. 454s are very prevalent in trucks but don’t forget that there are thousands of 30 year old RVs that had these along with boats.

Case in point here is an example near me. Reverse rotation Mark IV. While I am no expert on boat engines at all I do know this. Boat engines are designed to run all day at mid to upper RPMs. The example I listed I’m pretty sure has 4 bolt mains and likely has at a minimum the better flowing oval port heads of not the iron L88 style heads. Would the rotating assembly be usable in a car application? Probably not, but $1200 for a complete motor IMO isn’t bad provided it was winterized and not plum wore out. This is the kinda stuff I would be looking for as a foundation depending on what your budget is.

Fishfryer527

540 standard deck, mild cam, long L88 hood. It takes a lot to make a 454 frightening, go bigger.

Mdbirk

https://www.google.com/amp/s/www.mot...ine-build/amp/

OldCarBum

My opinion is go with the big block.
The 454 in my 73 is a kick to drive.
Don’t worry too much about the accessory brackets.
I purchased all new aftermarket ones for my new engine, they weren’t too expensive and the oem reproductions are just as nice as the originals.
Just be mindful of your build.
Building any engine which exceeds what the original drive train was designed for, can send you down the hi performance rabbit hole.

Bikespace

LS swap.

kossuth

Nope….. unless the OP specifically wants to swap, leave it in an OE configuration. Makes life far easier.

Lots of ways to f$ck up a car LS swapping it and making it an absolute PITA to drive and deal with. I’ve personally LS swapped or helped friends swap 4+ vehicles. This goes way back before there were kits also where we had to figure out everything. This includes my own 2000 S10 which I swapped in 2004. Love the LS platform but just no.

Bikespace

The car isn't in the original configuration now. I'm sure it won't be easy or cheap, but folks have stuffed 7.0L LS7s into C3s. That is a third option for 427 ci, other than the small block or big block.

Here's one example of a high-end restomod on this Forum.

https://www.corvetteforum.com/how-to...ette-c3-646763

Mdbirk

I thought ls swaps were for fox body mustang guys

Corvette-ZL1

It's sux that the original block is gone, as that affects the originality (and value of the car), so whatever the OP does, that will be a ding against the car. The caveat is if the OP goes the restomod route. As much as I hate to say it, originality goes out the door, but restomods are what's hot now (and for the past few years). It won't be like that forever, though. Eventually, originality will again bring top dollar over the restomods. Just a question of when...

Aside from the restomod approach, I agree with others that if it is a big block car, then it would be nice to see a big block in there again. It won't be numbers matching, but if the OP has no intention of selling it or entering the car into NCRS events, then who cares... just enjoy it for what it is - a classic Corvette.

As an example, look at this beast from BP Engines. That's a lot of motor for the price, IMO.

https://blueprintengines.com/collect...ns-br-seasoned